Advanced BioNutritionals CircO2 Reviews 2025: Ingredients, Complaints, Pricing, is It Legit
CircO2 Nitric Oxide Lozenges Review 2025: Full Ingredient List, Real Complaints, Pricing, and Legitimacy Guide
DENVER, September 22, 2025 (Newswire.com) - CircO2 is a dietary supplement. It is not intended to diagnose, treat, cure, or prevent any disease. Results vary. Always consult your doctor before starting any supplement. Always check the official website for the most current pricing and details, as they can change at any time. This article contains affiliate links. If you purchase through these links, a commission may be earned at no additional cost to you.
CircO2 Reviews 2025: Nitric Oxide Lozenges, Ingredients, Complaints, Pricing, Is It Legit?
TL;DR Summary: CircO2 is a nitric oxide supplement in fast-dissolving lozenges. Reviews highlight improved energy and circulation, but some complaints focus on pricing, taste, and varying results.
In This Article, You'll Discover:
Why CircO2 reviews and complaints dominate supplement searches in 2025
The science behind nitric oxide and how CircO2 works
A full ingredient breakdown with research-backed highlights
The biggest customer complaints and what they mean for buyers
Pros and cons from verified users
Pricing, refund policy, and buying options
Whether CircO2 is legit or a scam in today's supplement market
Introduction: Honest CircO2 Reviews and Complaints in 2025
When people search for nitric oxide supplements today, CircO2 by Advanced BioNutritionals appears at the top of the list. With more than 1,500 reviews and a 3.8-star average rating, CircO2 stands out as one of the most widely used nitric oxide formulas in the United States. But with its popularity also comes a mix of praise and criticism. That is why "CircO2 reviews and complaints" has become such a dominant search phrase in 2025.
The supplement market is flooded with pills, capsules, powders, and drinks that promise to increase nitric oxide levels. Many fail to live up to the hype. CircO2 positions itself differently by offering fast-dissolving lozenges designed to activate nitric oxide production directly in the mouth. According to Advanced BioNutritionals, this method leverages an MIT-backed discovery that the first step of nitric oxide conversion happens on the tongue, not in the gut. Supporters claim this makes the product more effective than traditional pills or powders.
From a consumer perspective, the demand for nitric oxide boosters is easy to understand. Nitric oxide plays a role in blood flow, oxygen delivery, energy, memory, stamina, and circulation. Research shows levels decline by up to 85% by age 80. That decline is linked to fatigue, memory lapses, reduced intimacy, and cold hands or feet. Products like CircO2 are marketed as a convenient way to reverse this decline.
Still, no supplement escapes scrutiny. CircO2's reviews highlight both positive experiences and complaints. Customers frequently report improved energy, stamina, and sleep. Others note that the product did not meet expectations or was too expensive to continue long term. Complaints about refund processing, taste, and inconsistent results also surface. These factors make it critical to analyze both sides before making a purchase.
In 2025, readers expect transparency. They want a balanced article that includes clinical references, verified user feedback, and details on pricing and refund terms. That is what this review aims to provide. Whether you are considering CircO2 for its energy and circulation claims or want to check if complaints outweigh the benefits, this guide will cover every angle.
Visit the Official CircO2 Website
What Is CircO2 and How Does It Work?
CircO2 is a fast-dissolving lozenge supplement created by Advanced BioNutritionals. Unlike pills or capsules that pass through the stomach, CircO2 is designed to activate nitric oxide production in the mouth. This delivery method is built on MIT research showing that the first and most important step in nitric oxide conversion happens on the tongue, where oral bacteria turn dietary nitrates into usable nitric oxide.
When you place a CircO2 lozenge on your tongue, it begins dissolving within seconds. This triggers nitric oxide production within 20 minutes. According to clinical testing cited by the company, this method raises nitric oxide levels by up to 200% in that timeframe and boosts blood flow by about 34%. Supporters argue this makes it more effective than common alternatives like beet juice, leafy greens, or L-arginine supplements, which can lose potency or become less effective with age.
The positioning of CircO2 is clear. It targets adults over 45 who want to maintain energy, circulation, and vitality as nitric oxide levels naturally decline. By age 70, the body's nitric oxide production can drop by 75%. By 80, that decline can reach 85%. This decline is linked to fatigue, memory problems, reduced intimacy, poor circulation, and joint discomfort. CircO2 is marketed as a solution to help reverse or reduce these effects.
Consumers often seek nitric oxide boosters for various reasons, and CircO2 addresses these needs with its natural ingredients. Whether you're looking for more stamina, sharper thinking, better blood pressure support, or improved intimacy through increased circulation, CircO2 has you covered. It combines nitrates from beet root powder with supporting ingredients like hawthorn berry, L-citrulline, vitamin C, vitamin B12, and magnesium, providing a natural and effective solution.
The format of CircO2, a fast-dissolving lozenge, is designed for your convenience. It seamlessly fits into your daily routine, eliminating the need for multiple capsules or powders. With no mixing, swallowing, or heavy dosing required, CircO2 offers a quick and discreet way to support nitric oxide levels during the day or before physical activity, making it a comfortable choice for your health needs.
It's important to manage expectations when using CircO2. It's not a prescription treatment, but a supplement designed to support healthy function. Results may vary based on age, health, and lifestyle. Some users report feeling an energy boost within minutes, while others say it takes weeks to notice changes. To ensure your confidence in the product, CircO2 includes a 90-day money-back guarantee, reducing any purchase risk and providing you with peace of mind.
Overall, CircO2's working principle centers on restoring nitric oxide levels in a fast, efficient way that aligns with modern research. Whether this translates to the benefits advertised depends on the user, but the method offers a distinct point of difference in a crowded supplement market.
Ingredient Breakdown
One of the most important factors readers look for in CircO2 reviews and complaints is the ingredient list. Transparency about what goes into a supplement matters because many nitric oxide products fail due to weak formulas, underdosing, or hidden fillers. CircO2 highlights a set of natural ingredients known for their ability to support nitric oxide production and circulation. While this ingredient profile comes directly from the official product page, always remember to review the label yourself, since formulations can change.
Beet Root Powder
Beet root has long been used by athletes for endurance. It contains nitrates that your body converts into nitric oxide, improving oxygen delivery to muscles and organs. Olympic-level athletes often use beet supplements for stamina. In CircO2, beet root serves as the base ingredient that starts the nitric oxide chain reaction in your mouth when the lozenge dissolves.
Hawthorn Berry
Traditionally used for heart health, hawthorn berry in CircO2 acts as an absorption booster. It helps maximize the amount of nitric oxide your body extracts from each lozenge. By supporting circulation and improving efficiency, hawthorn berry complements beet root and ensures users get more consistent results.
L-Citrulline
Unlike many supplements that rely on L-arginine, which can be less effective as you age, CircO2 uses the more reliable L-citrulline. This ingredient efficiently converts into nitric oxide, supporting circulation, stamina, and recovery. Its inclusion in CircO2's formula serves as a reassurance of its effectiveness for those over 45.
Vitamin B12
Vitamin B12 in CircO2 not only supports energy and nerve function but also plays a crucial role in nitric oxide production. This dual-purpose nutrient not only boosts vitality but also enhances circulation, providing users with a comprehensive health benefit.
Vitamin C
Vitamin C acts as a catalyst in the nitric oxide cycle. It protects existing nitric oxide molecules from oxidative damage, ensuring they last longer in the body. This helps extend the benefits of each lozenge and improves overall effectiveness.
Magnesium
Magnesium supports healthy blood vessels by helping them relax. It also regulates heart rhythm and aids recovery from physical activity. Since magnesium deficiency is common, its inclusion in CircO2 provides added value for cardiovascular support.
Other Supporting Nutrients
While the main ingredients do the heavy lifting, the formula also includes synergistic compounds designed to strengthen nitric oxide pathways. Together, these nutrients form what Advanced BioNutritionals calls a complete nitric oxide restoration system.
Ingredient Transparency Disclaimer
While the ingredient list here is based on information from the official Advanced BioNutritionals page, it's important to always verify the supplement facts panel before use. This empowers you to make informed decisions about the supplement's suitability for your individual needs, as individual responses to ingredients can vary.
CircO2 markets itself as more than a single-ingredient supplement. Instead, it combines nitrates, absorption enhancers, and protective nutrients into one lozenge. This approach is designed to maximize nitric oxide production while also addressing energy, stamina, and circulation concerns linked to aging.
See the Full Ingredient Details on the Official CircO2 Website
Pros and Cons of CircO2
When analyzing CircO2 reviews and complaints, it's important to balance both sides. Many users praise the product for boosting energy and circulation, while others voice concerns about pricing, taste, and inconsistent results. Here is a closer look at both the positives and negatives mentioned across reviews and customer feedback.
Pros of CircO2
Fast-Dissolving Delivery System
Convenient Delivery System CircO2's lozenges, unlike pills or capsules, dissolve on the tongue. This method, based on MIT research, directly supports nitric oxide production in the mouth. Many users find this format convenient as it eliminates the need to swallow multiple capsules.
Quick Nitric Oxide Boost
Clinical testing cited by the company shows CircO2 can raise nitric oxide levels by up to 200% within 20 minutes. Some users report feeling an energy lift or improved circulation soon after taking it, making it appealing for those seeking fast and immediate results.
Multi-Ingredient Formula
With beet root powder, hawthorn berry, L-citrulline, vitamin C, vitamin B12, and magnesium, CircO2 offers a broad set of nutrients. These ingredients are chosen not only for nitric oxide production but also for energy, stamina, and cardiovascular support.
Positive Consumer Reviews
From over 1,500 reviews, many highlight increased energy, improved sleep, better stamina, and reduced restless legs. While not every user experiences dramatic changes, a clear percentage of verified buyers report noticeable benefits.
90-Day Guarantee
The product includes a "Down to the Last Lozenge" guarantee. This means you can return it even if the box is empty within 90 days for a full refund. This robust refund policy not only lowers the risk for new buyers but also builds trust in the brand, ensuring your satisfaction is guaranteed.
Cons of CircO2
Inconsistent Results
Not everyone feels the same effects. While some users notice a difference in days, others report minimal changes even after finishing a full box. This inconsistency is a common theme in supplement complaints.
Taste and Dissolving Time
Because the lozenge must dissolve on the tongue, some users find the taste unpleasant or the texture uncomfortable. This format may not be suitable for everyone, especially those sensitive to flavored supplements.
Price Point
At nearly $50 per box, even with bulk discounts, CircO2 remains expensive. For long-term use, the monthly cost becomes a sticking point for many buyers. Complaints often mention that continuing the product is expensive compared to alternatives.
Refund Processing
Although a 90-day guarantee is advertised, some reviews mention delays or confusion when trying to process refunds. While most customers receive their money back, refund-related complaints surface enough to note them as a concern.
Not a Medical Treatment
CircO2 is a supplement, not an FDA-approved drug. It supports nitric oxide production but does not diagnose, treat, or cure health conditions. Some complaints stem from unrealistic expectations when buyers expect clinical-level results.
In short, CircO2 appeals to those looking for a convenient nitric oxide booster with science-backed delivery. The positives include its formulation, speed, and many reported benefits. The negatives are mostly tied to price, taste, and varying effectiveness. Understanding both sides helps buyers make informed decisions before purchasing.
See If CircO2 Is Right for You
The Biggest Complaints About CircO2
Even though CircO2 has thousands of buyers and many positive reviews, complaints remain an important part of the conversation. For a supplement in the nitric oxide category, it's normal to see a mix of praise and criticism. Looking closely at both positive and negative aspects provides a clearer picture of what new buyers should expect and how to avoid common frustrations.
Shipping and Delivery Issues
Some verified customers report delays with shipping or receiving their orders later than expected. While most packages arrive on time, shipping complaints appear in customer reviews, particularly for international orders. Buyers who live outside the United States sometimes experience longer wait times or customs-related delays.
Refund and Guarantee Confusion
CircO2 comes with a 90-day "Down to the Last Lozenge" guarantee. In theory, this allows customers to return empty boxes for a full refund. In practice, some complaints mention difficulties contacting customer service or delays in refund processing. These situations frustrate buyers who expected a hassle-free guarantee. To reduce this risk, it's best to order directly from the official website and keep a record of order confirmations and return tracking.
Taste and Texture Concerns
Since CircO2 uses lozenges instead of capsules, taste becomes a common theme in complaints. Some users describe the flavor as unpleasant or too strong, while others dislike how long the lozenge takes to dissolve. While taste is subjective, it's important for new buyers to know that the delivery format is different from typical pills.
Inconsistent Results
One of the most common complaints about CircO2 is that results vary widely. Some users feel energized within minutes, while others see no noticeable changes even after using the product for weeks. This inconsistency is often due to individual health, age, diet, and expectations. Like all supplements, CircO2 is not guaranteed to work the same way for everyone.
Pricing and Long-Term Cost
At $49.95 for a single box, CircO2 is on the higher end of the supplement spectrum. While bulk discounts reduce the price per box, some customers complain that the long-term cost makes it difficult to continue using. Reviews often mention that even satisfied users hesitate to commit long-term because of the recurring expense.
Customer Service Experiences
Most buyers report satisfactory service, but there are scattered complaints about long wait times on phone calls or difficulty reaching support staff by email. Some customers expected faster responses when dealing with refunds or shipping questions.
Health Expectation Misalignment
Finally, a number of complaints come from buyers who may have expected medical-grade results. CircO2 is marketed as a supplement to support healthy nitric oxide production, which can lead to improved circulation, energy levels, and overall health, not as a cure for health conditions. When buyers expect it to replace prescribed treatments, disappointment follows.
In summary, the main complaints about CircO2 center on shipping, refunds, taste, cost, and inconsistent outcomes. None of these issues automatically makes the product ineffective, but they do highlight the importance of setting realistic expectations and ordering through the official website to minimize problems.
Positive Reviews: Why Customers Like CircO2
Despite the complaints, many reviews highlight strong positive experiences with CircO2. With over 1,500 verified customer reviews and a 3.8-star average rating, a majority of buyers recommend the supplement. Positive reviews emphasize noticeable energy improvements, sharper thinking, and better circulation. Understanding why customers like CircO2 provides balance against the concerns and shows what benefits are most often reported.
Energy and Stamina
Many buyers describe feeling renewed energy within days or weeks of use. Some note that they can get through daily tasks without afternoon fatigue, while others mention improved exercise performance. One reviewer from Australia in September 2025 said CircO2 helped him regain the stamina to take on hobbies after work, describing a "reservoir of mental energy" at the end of the day.
Sharper Mental Clarity
Another common benefit mentioned in reviews is clearer thinking and better memory. Customers share stories of remembering names more easily, staying focused in conversations, and experiencing fewer "senior moments." While these results vary, the consistent theme is improved mental sharpness.
Better Sleep and Recovery
Several users report waking up feeling refreshed, rather than groggy. For some, this effect is tied to better circulation and oxygen delivery during the night. Others say CircO2 reduces restless legs, making it easier to rest. A verified buyer from Mississippi wrote in August 2025 that the product "really seems to help ease restless legs" when used consistently.
Improved Circulation and Blood Pressure Support
Some reviewers mention improved blood pressure readings, fewer cold hands and feet, and better overall circulation. This aligns with the nitric oxide mechanism of opening blood vessels and improving oxygen flow. While not every user reports measurable health changes, enough reviews highlight this benefit to make it a recurring theme.
Enhanced Intimacy and Vitality
Improved blood flow also translates to reported benefits in the bedroom. Several reviews reference increased performance and intimacy, though these are less common than energy or sleep benefits. This area of feedback appeals to men and women seeking vitality beyond daily stamina.
Customer Testimonials on Record
A reviewer from Washington state in September 2025 said he began noticing more energy after two weeks and plans to keep using the supplement.
A buyer from California described it as the "best nitric oxide supplement" after feeling more energy both at the gym and at home.
A customer from North Carolina highlighted improved motivation, better sleep, and a noticeable difference in overall well-being.
Why Positive Reviews Matter
For supplements, positive reviews often reflect real-world outcomes that go beyond clinical studies. Customers point out lifestyle improvements such as playing music at night, exercising more often, or sleeping better, which show how CircO2 fits into daily life. While not everyone experiences the same benefits, these accounts explain why many people reorder after their first box.
Overall, the positive feedback suggests that CircO2 delivers for those who respond well to nitric oxide support. Energy, sleep, mental clarity, and circulation are the most consistent benefits.
See Why Customers Recommend CircO2
Is CircO2 Legit or a Scam?
When searching for "CircO2 reviews and complaints," people often want to determine if the product is legitimate or part of the supplement scam category.This is an important question because the health market is full of overhyped products, exaggerated claims, and misleading billing practices. To determine whether CircO2 is legitimate or a scam, we must consider several key factors: transparency, refund policy, customer experiences, and overall business practices.
Transparency of Formula and Marketing
CircO2 openly lists its main ingredients, such as beet root powder, hawthorn berry, L-citrulline, vitamin C, vitamin B12, and magnesium. This level of transparency is a positive signal, providing you with the information you need to make an informed decision. Unlike scam products that hide behind 'proprietary blends' with no clear dosages, CircO2 provides details on how it works and why the lozenge delivery system matters. The company also cites research, such as MIT findings about nitric oxide production starting in the mouth. While not every claim is independently verified, the presence of ingredient details and scientific framing indicates legitimacy.
Refund Policy and Guarantees
CircO2 offers a 90-day "Down to the Last Lozenge" guarantee. This allows buyers to return the product, even if it's empty, for a full refund. This is significant because it gives customers ample time to try the product and see if it works for them. While some complaints mention delays or confusion with refunds, most customers report successful returns. Having a clear, time-bound guarantee with no hidden auto-billing is a strong sign the product is not a scam.
Customer Reviews and Ratings
With more than 1,500 reviews and a 3.8-star average rating, CircO2 clearly has a large base of real customers. This extensive feedback from the community can provide reassurance and a sense of belonging. Scam products typically lack verified reviews and instead rely on vague testimonials that lack dates or locations. CircO2's reviews include customer names, states, and dates, which helps confirm authenticity. While there are complaints about taste, price, and inconsistent results, these are typical of supplements, not red flags for fraud.
Billing and Ordering Practices
CircO2 is sold through the official Advanced BioNutritionals website, with prices clearly displayed. There are no hidden subscription traps where customers are automatically billed without consent. Buyers can choose between single or bulk orders, with free shipping available on larger purchases. Scam products often lure buyers with free trials or small upfront charges that lead to recurring billing. CircO2 does not use this tactic.
Expert Endorsement
The supplement is promoted by Dr. Frank Shallenberger, a physician with decades of experience in anti-aging medicine. While he is compensated for his involvement, his background adds legitimacy. It's important to note that his compensation does not necessarily mean his endorsement is biased or untrustworthy. Scam products often invent experts or use stock images. CircO2 provides verifiable details about its medical spokesperson.
Balancing Red Flags and Green Flags
The main red flags mentioned by customers are related to cost and inconsistent results, not fraudulent practices. The green flags include transparency, a clear refund policy, real customer reviews, and straightforward ordering.
Verdict: Legitimate, Not a Scam
CircO2 is a legitimate nitric oxide supplement backed by a recognized company. While it may not work for everyone and is more expensive than alternatives, the product is not fraudulent. The biggest risk for buyers is investing money and not experiencing the results they hoped for, which is a common outcome in the supplement industry. The refund policy helps reduce this risk.
Expert Insights and Industry Research
CircO2 is positioned within a fast-growing supplement market that has seen increasing consumer demand for nitric oxide support. To understand how it fits into this landscape, it helps to review what experts say about nitric oxide, consumer trends, and the supplement industry in 2025.
The Role of Nitric Oxide in Health
Medical literature describes nitric oxide as a signaling molecule critical for blood flow, oxygen delivery, and cellular communication. Researchers often call it the "endothelium-derived relaxing factor" because of its role in widening blood vessels. Studies show nitric oxide declines significantly with age, leading to fatigue, blood pressure challenges, and reduced circulation. This decline creates a market for products like CircO2 that claim to restore healthy levels.
Why Lozenges Are Different
Experts in oral microbiology emphasize that nitric oxide production begins in the mouth, not the gut. Bacteria on the tongue convert dietary nitrates into nitric oxide. Standard pills bypass this process, limiting their effectiveness. CircO2 leverages this research by using lozenges that dissolve in the mouth, a delivery method supported by established science. This scientific backing should instill confidence in the effectiveness of CircO2, even if not every expert endorses it specifically.
Supplement Adoption Statistics
Industry data shows that more than 70% of U.S. adults take at least one dietary supplement. Among older adults, circulation and heart support supplements are among the fastest-growing categories. Nitric oxide products are projected to grow in popularity because they target multiple concerns: energy, stamina, blood pressure, and healthy aging. CircO2 benefits from this demand by offering a unique delivery system that separates it from competitors, making it an intriguing option for those seeking nitric oxide support.
Affordability and Consumer Sentiment
While many consumers are willing to pay for supplements, price is a frequent barrier. A box of CircO2 costs about $49.95, with bulk discounts available. This positions it as a premium supplement compared to generic alternatives. Some experts argue that premium supplements maintain higher quality standards, but consumer complaints often center on affordability. This tension between perceived value and cost is typical across the supplement market, where consumers often weigh the potential benefits against the price of the product.
Trust and Compliance
Experts also stress the importance of compliance in supplement advertising. CircO2 avoids extreme claims like "cures" or "guaranteed results." Instead, it frames benefits around improved nitric oxide production, which is a safer approach from a regulatory standpoint. Industry analysts point out that supplements with transparent labeling, clear refund policies, and published disclaimers are more likely to maintain long-term credibility. CircO2 checks these boxes, which strengthens its legitimacy and should reassure potential buyers of its trustworthiness.
Overall Expert View
Industry experts see nitric oxide supplementation as an emerging area of interest, especially for aging populations. While more clinical trials are needed to fully confirm benefits, products like CircO2 align with scientific research on circulation and energy. Its lozenge format and inclusion of supporting nutrients, such as [specific nutrients], make it stand out compared to typical capsule-based formulas.
In short, expert insights and industry research support the idea that nitric oxide is important for aging health, that lozenge-based delivery has scientific merit, and that consumer demand is strong. The main concerns remain affordability and varied outcomes, which match the complaints highlighted earlier.
Comparing CircO2 vs Alternatives in 2025
When evaluating CircO2, it's natural to ask how it stacks up against other nitric oxide boosters and circulation supplements on the market. The supplement space in 2025 is crowded with powders, capsules, energy drinks, and beet-based products. CircO2 positions itself as unique because of its lozenge delivery system, but comparisons help buyers see whether the premium price is justified.
CircO2 vs L-Arginine Supplements
When it comes to CircO2 vs L-Arginine Supplements, the unique features of CircO2 stand out. Many nitric oxide products rely on L-arginine, but the body's ability to convert it into nitric oxide diminishes after age 45. This decrease in effectiveness is why many older adults do not notice much benefit. CircO2, on the other hand, uses L-citrulline, which converts more reliably into nitric oxide at older ages, bypassing this issue and providing a unique advantage.
CircO2 vs Beet Powders and Juices
When comparing CircO2 vs Beet Powders and Juices, the convenience of CircO2's lozenge format is a key advantage. Beet powders and juices, while effective, can be inconvenient due to the need for consistent dosing and their often earthy or unpleasant taste. CircO2, however, includes beet root powder in a lozenge form, making it more convenient for those who dislike the taste or bulk of powdered drinks. This format also ensures nitrates interact with oral bacteria, a crucial step for nitric oxide activation.
CircO2 vs Standard Capsules
When comparing CircO2 vs Standard Capsules, the early activation of nitric oxide by CircO2's dissolving lozenge format is a unique selling point. Most circulation supplements come in capsule form, which bypasses the mouth and goes straight to the stomach, missing the initial conversion step. CircO2's format, however, activates nitric oxide earlier in the process, a difference often highlighted in expert commentary and user testimonials.
CircO2 vs Cheaper Alternatives
Generic beet capsules and nitric oxide blends sell for far less, sometimes under $20 per bottle. CircO2 costs about $49.95 per box, or less in bulk. Complaints about price are common, but supporters argue that CircO2's method, ingredient blend, and refund guarantee justify the premium. Alternatives may be cheaper but often lack the same absorption strategy or supporting nutrients like vitamin B12, magnesium, and hawthorn berry.
Refund Terms and Trust Signals
CircO2 offers a 90-day guarantee that lets buyers try the product "down to the last lozenge," A major trust signal in an industry where subscription traps are common. Many cheaper alternatives have stricter refund policies or none at all. This transparency in returns is a major trust signal, making potential customers feel secure and confident in their purchase.
Cultural Presence and Reputation
CircO2 has established a reputation through thousands of verified reviews and a long-standing presence in the supplement market. Competing products often have fewer reviews or rely on aggressive advertising. With over 1,500 published customer reviews, CircO2 becomes more visible and easier to research.
Verdict on Comparisons
Compared to alternatives, CircO2 stands out for its unique delivery method, broad ingredient profile, and consumer trust signals. While it is more expensive, it offers features that many competitors do not. Those seeking budget options may choose standard beet supplements, but buyers willing to pay for convenience, science-backed delivery, and refund protection often lean toward CircO2.
Pricing, Refund Policy, and Where to Buy
Pricing is one of the most important details in CircO2 reviews and complaints. Many buyers praise the results but also note the supplement costs more than standard capsules or beet powders. To make an informed decision, it's essential to understand the pricing structure, refund guarantee, and safe buying practices.
Current Pricing Options
According to the official Advanced BioNutritionals website, CircO2 is available in three main order sizes:
1 Box (30 Lozenges) - $49.95 per box
3 Boxes (90 Lozenges) - $44.95 per box, total $134.85 (saves $15)
6 Boxes (180 Lozenges) - $41.50 per box, total $249.00 (saves $50.70)
Larger orders include free shipping, while single-box orders may require additional shipping fees. These discounts are designed for buyers who want to use CircO2 long-term and reduce the monthly cost.
Refund Policy
CircO2 comes with a "Down to the Last Lozenge" 90-day money-back guarantee. This means buyers can return even empty boxes for a full refund if they are not satisfied. While most customers report successful refunds, some complaints mention delays or confusion during the process. To make returns easier, it's recommended to keep the original order confirmation and track your return shipment.
Where to Buy Safely
CircO2 is sold exclusively through the official Advanced BioNutritionals website. Buying directly ensures you receive the authentic product, qualify for the 90-day guarantee, and avoid counterfeit supplements that appear on third-party sites. Purchasing from unauthorized sellers may put you at risk of expired, tampered, or fake versions with no refund protection.
Counterfeit Warnings
As CircO2 gains popularity, imitations appear on discount websites and online marketplaces. These may look similar but often lack the correct formula or guarantee. Customer complaints frequently highlight issues when products are purchased outside the official site. To avoid this, always order directly through the verified link.
Pricing Disclaimer
All supplement prices are subject to change at any time. Always check the official website for the most up-to-date pricing, shipping, and promotional offers.
Why Pricing Matters in Complaints
Personal health priorities and budget play a significant role in the decision to purchase CircO2. While the supplement may not be budget-friendly at $40-$50 per box, positive reviews highlight benefits such as increased energy, better circulation, and improved sleep that can justify the price. This empowers potential buyers to make a decision that aligns with their health and financial goals.
Verdict on Pricing and Refunds
While circO2 may cost more than generic alternatives, it offers premium features, a transparent guarantee, and verified customer support. For buyers who value convenience and a risk-free trial, CircO2 presents a strong value proposition, providing reassurance about their purchase decision.
Safety, Risks, and Responsible Use
When looking at CircO2 reviews and complaints, many buyers want to know if the supplement is safe to use. Since it targets nitric oxide levels, which influence blood flow and circulation, safety is a valid concern. Like any supplement, CircO2 has both benefits and precautions that should be considered before long-term use.
General Safety Profile
CircO2 is marketed as a dietary supplement, not a prescription drug. Its main ingredients-beet root powder, hawthorn berry, L-citrulline, vitamin B12, vitamin C, and magnesium-are commonly used in health products. For most adults, these nutrients are well-tolerated when taken at recommended doses. Many verified reviews confirm that users experienced benefits without serious side effects.
Potential Side Effects
Some users report mild effects such as:
Temporary dizziness if taken on an empty stomach
Digestive discomfort, such as mild nausea or bloating
Unfavorable taste during lozenge use
Warmth or tingling due to increased circulation
These side effects are generally mild and fade as the body adjusts. Complaints about side effects are less common than complaints about price or shipping, but they do appear in customer feedback.
Who Should Use Caution
Certain groups should consult a healthcare provider before trying CircO2:
People taking blood pressure medication or blood thinners
Individuals with heart conditions or circulation disorders
Pregnant or breastfeeding women
Those with chronic health conditions who are under active medical care
Because CircO2 may influence blood pressure and circulation, combining it with prescription medications could create risks if not monitored by a doctor.
Responsible Use Guidelines
Take CircO2 exactly as directed on the package. Do not exceed the recommended dosage.
Allow the lozenge to fully dissolve in your mouth to maximize nitric oxide activation.
Store the product in a cool, dry place to preserve potency.
Track your response over several weeks, as results may take time to appear.
Always consult your healthcare provider if you have medical conditions or take prescriptions.
Health Disclaimer
CircO2 is not intended to diagnose, treat, cure, or prevent disease. Individual results vary, and benefits should be considered supportive, not therapeutic.
Why Safety Comes Up in Complaints
Some complaints mention headaches, stomach upset, or no results after weeks of use. These are common issues across supplements and often reflect individual sensitivity. Most users tolerate CircO2 well, but expectations and responsible use are key to minimizing disappointment.
Verdict on Safety
CircO2 is generally safe for healthy adults when used as directed. The most important step is consulting a healthcare professional if you have pre-existing conditions or take other medications. Responsible use reduces risks and increases the chance of positive results.
See Safety Guidelines for CircO2 on the Official Website
User Testimonials and Case Studies
Beyond clinical claims and ingredient lists, real-world testimonials show how CircO2 fits into the lives of a diverse range of users. With more than 1,500 reviews published and a 3.8-star rating, CircO2 has a broad customer base that includes older adults, active individuals, and those seeking specific health improvements. Here are the main patterns seen in user stories and case-style feedback, showcasing the inclusivity of the CircO2 community.
Active Adults and Athletes
Several customers mention improved stamina during exercise or daily activity. For example, one verified reviewer from California in September 2025 described CircO2 as the "best nitric oxide supplement" after noticing more energy both at the gym and at home. These accounts suggest CircO2 appeals to both casual exercisers and people who want endurance for hobbies or routines.
Older Adults Seeking Vitality
A significant group of reviewers are adults over 60 who use CircO2 to counter the effects of aging. One customer from Arizona reported in July 2025 that the supplement "lifted me up some" after a month of use, reflecting modest but positive improvements. Others say it helps with circulation, reducing cold hands and feet, and supporting daily energy.
Cognitive and Mental Clarity Support
Some testimonials focus on sharper memory and mental stamina. A reviewer from Australia in September 2025 shared that CircO2 gave him enough evening energy to continue online guitar lessons after work, something he struggled with before. Stories like this show how perceived energy improvements translate into meaningful lifestyle changes.
Sleep and Restlessness Relief
CircO2 reviews also include feedback about better sleep. A verified customer from Mississippi noted that consistent use seemed to reduce restless legs, making sleep easier. This type of testimonial adds depth to the benefits by showing how circulation improvements influence rest and recovery.
Health-Conscious Buyers
Case-style accounts often come from people who already eat well, exercise, and take supplements. For them, CircO2 is another tool in a broader health strategy. These buyers usually highlight small but noticeable improvements, like steadier energy, faster recovery, or healthier blood pressure readings.
Why Case Studies Matter
Testimonials are not clinical proof, but they reveal how the supplement fits into daily routines. While some buyers report dramatic results, others describe gradual improvements that build over weeks. This gradual progress underscores why CircO2 offers a 90-day guarantee, instilling patience and hope in users as they wait for the product's long-term benefits to manifest.
Balanced Perspective
Even satisfied customers admit CircO2 is costly and requires consistent use. However, they continue reordering because the benefits-more energy, better sleep, or improved stamina-outweigh the negatives for them. This balanced perspective provides valuable reassurance for new buyers, helping them feel confident in their decision to try CircO2.
Read Verified Experiences With CircO2 Here
Frequently Asked Questions About CircO2 Reviews and Complaints
As CircO2 gains more attention, buyers ask similar questions about safety, pricing, shipping, and results. Addressing these FAQs helps clear up confusion and set realistic expectations.
Here are the most common questions from potential and current users.
1. Is CircO2 safe to use daily?
For most healthy adults, CircO2 is safe for daily use. Its ingredients are commonly used in dietary supplements, providing a reassuring safety profile. However, it's always best to consult your doctor if you are pregnant, breastfeeding, or taking medications for blood pressure or heart conditions.
2. How long does it take to feel results?
Some users report changes within 20 minutes of their first lozenge. Others notice benefits after a few days or weeks. Because nitric oxide levels vary by age and health, results differ.
3. What are the main side effects?
Mild complaints include digestive upset, dizziness, or a lingering taste. Side effects are usually temporary and fade with continued use. Serious side effects are rare, but medical consultation is recommended if you have pre-existing conditions.
4. What do the biggest complaints say?
The most common complaints mention high price, inconsistent results, refund delays, and taste. These concerns don't mean the product is a scam, but they highlight what new buyers should expect.
5. Does CircO2 help with blood pressure?
CircO2 is marketed as a supplement to support healthy circulation and nitric oxide levels. While it is not a medical treatment, some customers have reported better blood pressure readings, instilling hope for potential benefits. However, results vary and it should not replace prescribed medications.
6. How should I take CircO2?
To get the most out of CircO2, place one lozenge on your tongue and allow it to dissolve fully. This process activates nitric oxide production by the oral bacteria. Remember, do not chew or swallow the lozenge whole, as this may affect its effectiveness.
7. Can I take CircO2 with other supplements?
Yes, but it's best to review your full supplement list with a healthcare provider to avoid unnecessary overlap, especially with products targeting circulation or blood pressure.
8. What makes CircO2 different from standard nitric oxide capsules?
Most capsules dissolve in the stomach. CircO2 activates nitric oxide production in the mouth, where the process begins naturally. This is its key differentiator.
9. Is CircO2 FDA-approved?
No. CircO2 is a dietary supplement. The FDA does not approve supplements for treating medical conditions. Advanced BioNutritionals follows standard supplement manufacturing practices but does not make FDA approval claims.
10. Where should I buy CircO2?
Always order from the official Advanced BioNutritionals website. This ensures you receive the authentic product and qualify for the 90-day guarantee. Avoid third-party sellers to reduce the risk of counterfeit or expired products.
11. How does the refund policy work?
WithCircO2, you can shop with confidence. We offer a 90-day "Down to the Last Lozenge" guarantee. If you're not satisfied, simply return the product, including empty boxes, for a full refund. To ensure a smooth process, keep your order confirmations and tracking details handy.
12. Can CircO2 replace prescription medication?
No. It is a dietary supplement meant to support nitric oxide levels, not a substitute for medical treatment. Always follow your doctor's guidance for prescriptions.
13. What does the average rating mean?
CircO2 has a 3.8-star average rating across 1,500+ reviews. That means many customers recommend it, but there are also mixed experiences. This balance reflects both satisfied buyers and those who saw little to no change.
14. Do I need to take CircO2 twice a day?
Follow the directions on the package. Most users take one lozenge daily. Some choose two for added support, but consult your doctor before increasing dosage.
15. What happens if I stop taking it?
Nitric oxide levels will gradually return to natural baseline levels. Any benefits you experienced, such as improved stamina or circulation, may fade over time.
These FAQs reflect the most common concerns surrounding CircO2. By reviewing them, buyers can better decide whether the supplement matches their needs.
Get Answers and Order CircO2 Directly From the Official Website
Bonus Tips: How to Avoid CircO2 Complaints
While many buyers are satisfied with CircO2, the most common complaints come from issues that can be prevented. By taking a few simple steps, you can minimize frustration and improve your overall experience with the supplement.
Order Direct From the Official Website
Many complaints about counterfeit products, missing refunds, or expired stock come from buying CircO2 through third-party sites. Ordering only from the official Advanced BioNutritionals website ensures you get the authentic product, qualify for the 90-day guarantee, and avoid fake supplements.
Track Your Shipment
Shipping complaints often involve delays or misplaced packages. Always save your order confirmation and use tracking to monitor delivery progress. If you live outside the United States, expect longer delivery times and plan ahead by ordering in bulk.
Manage Refunds Proactively
The 90-day "Down to the Last Lozenge" guarantee is valid, but some buyers run into issues when they don't follow instructions. Keep the original packaging, save your invoice, and use tracked return shipping. Contact customer service early if you think you'll need a refund.
Consult Your Doctor First
Some complaints about side effects come from people who took CircO2 without considering medications they were already using. If you take prescriptions for blood pressure or heart conditions, review CircO2 with your doctor before starting. This step reduces the chance of unexpected interactions.
Set Realistic Expectations
Not everyone will feel results in the first few days. Some reviews mention benefits after weeks of consistent use. Go into the trial knowing that results vary by age, health, and lifestyle. If you don't notice changes, the refund guarantee gives you protection.
Be Consistent With Use
Skipping days or taking lozenges irregularly lowers effectiveness. For best results, let one lozenge dissolve fully each day and stick to the routine. Consistency often separates satisfied buyers from those who felt no results.
Avoid Anonymous Reviews
Many buyers get swayed by vague online reviews with no verifiable details. Stick with reviews on the official website or trusted platforms where dates, names, and locations are included. These are more reliable indicators of real-world experiences.
By following these steps, you can lower the risk of running into the most common CircO2 complaints. Responsible use, ordering smart, and keeping expectations realistic go a long way in improving satisfaction.
Order CircO2 With Confidence Through the Official Website
Final Verdict: Should You Try CircO2 in 2025?
CircO2 stands out in the nitric oxide supplement market because of its delivery system, ingredient blend, and consumer reputation. With more than 1,500 reviews and a 3.8-star rating, it has proven appeal but also sparks debates over cost, taste, and consistency. The question for buyers in 2025 is whether its benefits outweigh the downsides.
Strengths of CircO2
Fast-dissolving lozenges activate nitric oxide in the mouth, where the process naturally begins.
Clinical testing shows a 200% increase in nitric oxide levels within 20 minutes.
Includes beet root powder, L-citrulline, hawthorn berry, and vitamins that support circulation and energy.
Thousands of customer reviews highlight improved stamina, sharper thinking, better sleep, and circulation support.
A 90-day "Down to the Last Lozenge" guarantee reduces purchase risk.
Weaknesses of CircO2
Premium pricing makes long-term use costly compared to capsules or powders.
Some users dislike the taste or find lozenges inconvenient.
Refund complaints appear in reviews, usually tied to delays or return processing.
Results are inconsistent-some buyers notice changes within days, while others report little to no effect.
Who CircO2 Is Best For
Adults over 45 seeking support for circulation, stamina, and vitality as nitric oxide levels decline.
Health-conscious buyers who value convenience and are willing to pay more for a premium formula.
Individuals open to trying a supplement for 60-90 days with realistic expectations.
Who Might Not Benefit
Buyers on a tight budget who prefer lower-cost alternatives like beet powders or generic blends.
People are expecting medical-grade results or a replacement for prescription treatments.
Those who are highly sensitive to taste or who dislike lozenge-style supplements.
Legitimacy Verdict
CircO2 is not a scam. It is a legitimate supplement produced by Advanced BioNutritionals, supported by scientific reasoning and customer reviews. The main risk lies in personal response and cost-not fraud or hidden charges.
Should You Try It?
If you are looking for a nitric oxide supplement in 2025 and want a delivery method based on modern research, CircO2 offers a compelling option. It isn't the cheapest product, and it won't work for everyone, but the formula, guarantee, and user experiences make it worth considering. With the refund policy in place, trying it for a full box or two poses minimal risk.
Final Thought
CircO2 is best suited for buyers seeking circulation and energy support with a willingness to invest in a premium product. If you value transparency, real customer feedback, and a money-back guarantee, CircO2 deserves a spot on your short list.
Decide If CircO2 Works for You Today
Contact Information
For questions, support, or refund requests regarding CircO2, you can reach Advanced BioNutritionals directly using the details provided below. Contacting the company through official channels ensures faster service and access to the 90-day guarantee.
Company: Advanced BioNutritionals
Email: [email protected]
Phone (Toll-Free, US): 800-613-5721
Phone (Local): 678-987-5891
Disclaimers
Publisher Responsibility Disclaimer: The publisher of this article has made every effort to ensure accuracy at the time of publication. We do not accept responsibility for errors, omissions, or outcomes resulting from the use of the information provided. Readers are encouraged to verify all details directly with the official source before making a purchase decision.
FTC Affiliate Disclosure: This article contains affiliate links. If you purchase through these links, a commission may be earned at no additional cost to you.
FDA Health Disclaimer: CircO2 is a dietary supplement. These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. Always consult a licensed healthcare professional before starting any new supplement, especially if you have pre-existing medical conditions or are taking prescription medications.
Results May Vary: Individual experiences with CircO2 differ. Some users may feel results quickly, while others may require consistent use over weeks. Benefits such as energy, circulation, or stamina support are not guaranteed and depend on personal health factors.
Pricing Disclaimer: Prices, discounts, and shipping policies for CircO2 are subject to change at any time. Always check the official Advanced BioNutritionals website for the most up-to-date information before ordering.
Medical Disclaimer: The content in this review is for informational purposes only. It should not be taken as medical advice, diagnosis, or treatment guidance. If you have health concerns, please consult your doctor.
Legitimacy Note: Dr. Frank Shallenberger, who endorses CircO2, is compensated by Advanced BioNutritionals. His support does not guarantee individual results.
Contact Information
Advanced Bionutritionals Customer Support
[email protected]
800-613-5721
Source: Advanced Bionutritionals
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Tags: circulation support, energy health, nitric oxide, supplement reviews, wellness trends
