Worth it if you're over 40, notice fatigue, cold hands and feet or fading stamina, and want gentle daily circulation support built on 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 gotcha most reviews miss: antibacterial mouthwash can cancel the whole effect.
What CircO2 actually is
CircO2 is a nitric oxide supplement from Advanced Bionutritionals. Unlike a capsule, it comes as a fast-dissolving lozenge you let melt in your mouth. That format isn't a gimmick — nitric oxide activation starts in the mouth, where beneficial bacteria convert the formula's nitrate. As we age, natural nitric oxide production drops, and with it goes circulation, stamina and that easy all-day energy.
It's aimed at adults over 40 who notice the early signs of slowed circulation: fatigue, cold hands and feet, stiffness, or stamina that isn't what it used to be.
What works
- Built on Nobel Prize-winning nitric oxide science
- Fast-dissolving lozenge — quick absorption
- Beetroot + L-citrulline, not just one ingredient
- Supports circulation, stamina 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
- Won't work if you use antibacterial mouthwash
- Lozenge taste isn't for everyone
- Results build over 1–3 months
- One lozenge daily — easy to forget
- Best value only on multi-box orders
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 killing the activating bacteria (see above), or stopping too soon. Circulation benefits build over one to three months of daily use, not overnight.
"The taste is odd."
The lozenge has a distinct beet-forward taste because it's designed to dissolve slowly in the mouth. Most people adjust within a few days. If you can't stand it, the guarantee has you covered.
How CircO2 compares to capsule nitric oxide pills
| Factor | CircO2 lozenge | Typical NO capsule |
|---|---|---|
| Activation | Starts in the mouth, fast | Must pass through digestion first |
| Ingredients | Beetroot + L-citrulline blend | Often L-arginine alone |
| Self-test | 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 40+, notice fatigue, cold extremities or fading stamina, 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 won't change that, or you want an instant pre-workout pump.
Check today's price & multi-box discount
Lowest cost per box is on the multi-box 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 stamina 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 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 around your dose. The other reason is stopping too soon — benefits build over one to three months.
How do I take CircO2?
Dissolve one lozenge slowly in your mouth daily, letting it melt rather than chewing or swallowing it whole. The slow dissolve is what lets the mouth activate nitric oxide production.
Is CircO2 a scam?
No. It is a real lozenge from Advanced Bionutritionals, made in the USA with a 90-day money-back guarantee, and built on Nobel Prize-winning nitric oxide research. It is not a miracle cure and results vary by individual.