CircO2 Review: does this nitric oxide lozenge really work?
A clear look at CircO2 — including the blood-pressure warning and the common mouthwash mistake that silently stops it from working.
Worth it if you're over 40, noticing fatigue, cold hands and feet or fading vigor, and want gentle, daily circulation support backed by real nitric-oxide science. Check with your doctor first if you take blood-pressure medication — nitric oxide lowers blood pressure, and the effects can stack. The hidden catch most reviews don't mention: antibacterial mouthwash can cancel out the entire effect.
What CircO2 actually is
CircO2 is a nitric oxide supplement from Advanced Bionutritionals. Unlike a capsule, it comes as a fast-dissolving lozenge that melts in your mouth. This format isn't a marketing gimmick — nitric oxide activation begins in the mouth, where beneficial bacteria convert nitrate from the formula. As we age, natural nitric oxide production declines, and with it goes circulation, vigor and easy energy throughout the day.
It's aimed at adults over 40 who are noticing the early signs of sluggish circulation: fatigue, cold hands and feet, stiffness, or vigor that isn't what it used to be.
What works
- Nobel Prize-winning nitric oxide science
- Fast-dissolving lozenge — quick absorption
- Beetroot + L-citrulline, not just one ingredient
- Supports circulation, vigor and heart health
- Includes a strip to test your nitric oxide levels
- 90-day money-back guarantee
What to know first
- Can lower blood pressure — caution if medicated
- Doesn't work if you use antibacterial mouthwash
- The lozenge taste isn't for everyone
- Results build over 1–3 months
- One lozenge a day — easy to forget
- Best value only on multi-bottle orders
The detail almost no review mentions: nitric oxide activation depends on good bacteria in your mouth. If you use antibacterial mouthwash, it can wipe out exactly the bacteria CircO2 needs — cutting the whole effect. Avoid mouthwash around your dose, and the lozenge can do its job.
The complaints nobody addresses — answered
"I'm on blood-pressure medication — is it safe?"
This is the one that matters most. Nitric oxide naturally relaxes blood vessels and lowers blood pressure. Combined with blood-pressure medication, that effect can stack. This isn't a reason to panic — it's a reason to talk to your doctor before starting, especially if you take cardiovascular medication.
"I didn't notice anything."
Two common causes: antibacterial mouthwash wiping out the activating bacteria (see above), or stopping too early. Circulation benefits build over one to three months of daily use, not overnight.
"The taste is odd."
The lozenge has a distinct beet flavor because it's designed to dissolve slowly in your mouth. Most people adjust within a few days. If you really can't stand it, the guarantee has you covered.
How CircO2 compares to nitric oxide capsules
| Factor | CircO2 Lozenge | Typical NO Capsule |
|---|---|---|
| Activation | Starts in the mouth, fast | Must pass through digestion first |
| Ingredients | Beetroot + L-citrulline blend | Often just L-arginine |
| Self-testing | Includes test strips | Rarely included |
| Best for over 40 | Yes — gentle daily support | Varies |
Who it's for — and who should skip it
Buy it if you're over 40, noticing fatigue, cold extremities or fading vigor, and want gentle, daily circulation support. Talk to your doctor first if you take blood-pressure or heart medication. Skip it if you rely on antibacterial mouthwash and aren't willing to change that, or want an instant pre-workout effect.
Check today's price & multi-bottle discount
The lowest cost per bottle is on the multi-bottle order, which also unlocks free shipping. The 90-day guarantee lets you test it risk-free.
See Pricing & Availability →Frequently asked questions
Does CircO2 really work?
Many users report better circulation, steadier energy and improved vigor within a few weeks, with fuller benefits over one to three months. It works by boosting nitric oxide, which relaxes blood vessels and improves blood flow. Consistency matters.
Is CircO2 safe with blood-pressure medication?
Use with caution. Nitric oxide naturally lowers blood pressure, so combining CircO2 with blood-pressure or cardiovascular medication can amplify that effect. Talk to your doctor before starting if you take any such medication.
Why isn't CircO2 working for me?
The most common reason is antibacterial mouthwash, which kills the mouth bacteria that activate the nitrate in the lozenge. Avoid antibacterial mouthwash near your dose. The other reason is stopping too early — benefits build over one to three months.
How should I take CircO2?
Dissolve one lozenge slowly in your mouth each day, letting it melt rather than chewing or swallowing it whole. Slow dissolving is what allows your mouth to activate nitric oxide production.
Is CircO2 a scam?
No. It's a real lozenge from Advanced Bionutritionals, made in the USA with a 90-day money-back guarantee, and based on Nobel Prize-winning nitric oxide research. It's not a miracle cure, and results vary by individual.