The20 · Men's Health
The 20
FLOW: food-derived citrulline for circulation and intimacy.
What FLOW by The20 is, its organic watermelon citrulline, acerola and pine bark formula, how to take it, how the subscription and 364-day refund work, and what to know before you start.
- Food-derived citrulline
- Published dose
- Vitamin C and pine bark
- Clean formula
- Independent overview
- Opens the official store
- Terms are set by the seller
Last reviewed by the Wellness Center USA editorial team
- Per two-capsule dose
- 850 mg
- Capsules per bottle
- 60
- Refund window
- 364-day
- Food-derived citrulline
- Organic
The idea behind it
Blood flow, from fruits and vegetables.
FLOW is built around supporting the body's own nitric oxide. Here is the thinking in plain terms, with the brand's claims kept as the brand's claims.
Nitric oxide support
Nitric oxide helps blood vessels relax and widen. The brand says levels decline with age.
Food-derived citrulline
Citrulline made by fermenting organic watermelon and organic spinach, rather than from corn-based powders.
Absorption and circulation
Vitamin C from organic acerola cherries and pine bark extract, according to the brand.
For men and women
The brand says it is formulated for everyone, supporting circulation, energy, sleep and intimacy.
“Active blood-flow support from organic watermelon and organic spinach.”
Formula, compared
Arginine powder, a prescription pill, or food-derived citrulline?
How FLOW's approach differs from other options. The FLOW column reflects the brand's own description.
- Arginine powder
Synthetic amino acid
- Usually made by fermenting corn
- Large doses often needed
- Can upset the stomach
- Prescription ED medicine
Medical treatment
- Prescribed after a check-up
- Tested in large trials
- Not for use with nitrates
- FLOW
Organic citrulline blend
- Watermelon and spinach citrulline
- Acerola vitamin C
- Pine bark extract
- Two small capsules a day
What's inside
Three active ingredients, 850 mg per dose.
The ingredients The20 lists for FLOW. The brand says 100% of the ingredients are on the label.
- Key ingredient
L-citrulline from organic watermelon and spinach
An amino acid the body converts to arginine and then nitric oxide. FLOW's is made by fermenting organic watermelon and spinach, the brand says.
- Vitamin C
Vitamin C from organic acerola cherry
A tropical cherry very rich in vitamin C, which the brand says improves the absorption of citrulline.
- Circulation
Pine bark extract (Pinus pinaster)
An extract from the maritime pine, rich in procyanidins, included for its circulatory effects and to sustain nitric oxide production.
- Excipients
Clean excipients
A small amount of organic rice flour as a flow agent and tapioca starch from processing; no magnesium stearate. Capsules are gelatin.
FLOW by the numbers
- Capsules daily
- 2
- Day supply per bottle
- 30
- Days to return unused product
- 364
- Age the brand suggests starting
- 40+
Side by side
How FLOW compares.
The FLOW column comes from the official store. The second column describes a typical L-arginine supplement in general, not any specific product.
| Feature | FLOW | Typical arginine supplement |
|---|---|---|
| Main nitric oxide ingredient | L-citrulline | L-arginine |
| Food-derived, organic source | Yes, (per the brand) | Varies |
| Vitamin C and pine bark | Yes | Varies |
| Dose published | Yes, (850 mg) | Yes |
| Vegetarian capsules | ✗ (gelatin) | Varies |
| Sold as a subscription | Yes, (cancel anytime) | Varies |
| Refund window | 364 days, unused portion | Varies |
✓ = present according to the brand · ✗ = not present · Varies = depends on the product.
Want to check current availability and details?
Visit the official The20 websiteGood to know
Before you start
A few points worth checking before taking FLOW:
- Blood pressure and heart medicines. Citrulline can lower blood pressure. Do not combine it with sildenafil, tadalafil or similar medicines, nitrate heart medicines such as nitroglycerin, or blood pressure tablets without your doctor's advice.
- Low blood pressure. Stop and seek advice if you feel dizzy or faint.
- Pregnancy and age. The brand advises consulting a professional if you are pregnant, breastfeeding, trying to conceive or under 18.
- Gelatin. The capsules are not suitable for vegetarians or vegans.
- See a doctor about erection problems. They can be an early sign of heart disease or diabetes.
Subscription
How the FLOW offer works
The offer reached through the official link is a subscription, not a one-time purchase:
- First bottle: you pay only shipping.
- After that: a monthly charge for a new bottle, at a 25% subscription discount, until you cancel.
- Cancel anytime: the store says you can cancel at any time.
Check the terms at checkout, note your renewal date, and keep the store's contact details so you can cancel if you decide not to continue.
The evidence
What is known about citrulline and pine bark
We found no published clinical trial of FLOW itself. The research below is about individual ingredients.
L-citrulline is well established as a building block the body uses to make arginine and nitric oxide, and studies show that taking it raises arginine levels in the blood more reliably than taking arginine itself. Small trials have looked at citrulline for mild erection problems and for exercise recovery, with modest, encouraging results; larger trials are lacking. The brand notes that citrulline has self-affirmed GRAS status in the US — meaning the manufacturer has concluded it is generally recognised as safe in food.
Pine bark extract has been studied in combination with arginine for erection problems and for circulation, again in small trials. Vitamin C is an essential nutrient and antioxidant. Spinach is a natural source of nitrates, which the body can also turn into nitric oxide.
In plain terms: FLOW's ingredients have a sensible rationale and some early evidence, and its dose is published, but the finished capsule has not been tested. It is not a substitute for prescription treatment where that is needed.
Good to know
What else supports healthy blood flow
The brand itself highlights lifestyle habits for better circulation, and they have the strongest evidence:
- Exercise regularly — it is one of the best ways to support healthy blood vessels.
- Don't smoke, and keep alcohol moderate.
- Eat nitrate-rich vegetables such as spinach, beetroot and leafy greens, plus healthy fats from nuts, seeds and olive oil.
- Cut back on added sugar and manage stress, both linked to heart and vascular health.
Simple routine
Getting started with FLOW.
Check with your doctor first if you take blood pressure, heart or erectile dysfunction medicines.
Take two capsules daily, morning or evening, as the official store directs.
Note your subscription renewal date, and keep any unused product in case you want a refund.
Refund policy
What the 364-day guarantee says.
The20 says that if you are not 100% satisfied with FLOW, you can return the unused portion within 364 days of purchase and its customer care team will issue a full refund of the purchase price, less any shipping and handling fees. These are the seller's terms as published, not a guarantee from us.
- 364 days from purchase
- Return the unused portion
- Refund less shipping and handling
- Subscription can be cancelled anytime
Is it right for you?
Questions to ask before buying.
- Do you take blood pressure, nitrate or erectile dysfunction medicines? Ask your doctor first.
- Have you discussed erection or arousal problems with a doctor, to rule out heart disease or diabetes?
- Are you happy with a monthly subscription, and do you know how to cancel?
- Are you vegetarian or vegan? The capsules are gelatin.
- Are you pregnant, breastfeeding or trying to conceive?
- Have you noted the refund terms — 364 days, unused portion, less shipping?
Ordering
Buying, subscription and the official store.
FLOW is sold through The20's official store. The offer reached through the official link is a monthly subscription: the first bottle is free apart from shipping, then a bottle is sent and charged each month at a subscription discount until you cancel.
Supply. Each bottle holds 60 capsules, a 30-day supply at two capsules a day. If you also take the extra serving the brand suggests before intimacy, you will need more than one bottle a month.
Packaging. The brand uses recyclable HDPE plastic bottles.
Support. The20 says it has supported customers since 2006, and its customer care team handles cancellations and refunds.
Specifications
FLOW at a glance
As published on the official store. Details the store does not give are marked as not stated.
- Product
- FLOW Nitric Oxide Booster®
- Brand
- The20
- Form
- Size 0 gelatin capsules
- Suggested use
- 2 capsules daily (850 mg); optional extra 2 before intimacy
- Active ingredients
- L-citrulline from organic watermelon and spinach, vitamin C from organic acerola, pine bark extract (Pinus pinaster)
- Individual amounts
- Not stated (850 mg total per dose)
- Excipients
- Organic rice flour; tapioca starch from processing
- Free from
- Gluten, sugar, lactose, soy, GMOs, magnesium stearate (per the brand)
- Capsules per bottle
- 60 (30-day supply)
- Purchase type
- Monthly subscription, cancel anytime
- Refund window
- 364 days; unused portion, less shipping and handling
- Manufacturing
- USA, family-owned manufacturer (per the brand)
At a glance
Key features
Food-derived citrulline
Made from fermented organic watermelon and spinach, according to the brand.
Published dose
850 mg per two-capsule serving.
Vitamin C and pine bark
Organic acerola cherry and Pinus pinaster extract.
Clean formula
Gluten-, sugar-, lactose- and soy-free, with no magnesium stearate.
364-day refund window
A refund on the unused portion, less shipping and handling, under the seller's terms.
What it's made of
Ingredients & materials
- L-citrulline
- From fermented organic watermelon and organic spinach.
- Vitamin C
- From organic acerola cherries.
- Pine bark extract
- Pinus pinaster, from the maritime pine. Gelatin capsules with organic rice flour.
The details
Overview
The20 is the brand behind FLOW Nitric Oxide Booster®, a capsule supplement sold through its official store. The brand describes it as "active blood-flow support from organic watermelon and organic spinach" that "supports healthy circulation, energy, sleep and sex," and says it is "formulated for both men and women." FLOW is built around L-citrulline made by fermenting organic watermelon and organic spinach, combined with vitamin C from organic acerola cherries and pine bark extract (Pinus pinaster). The dose is two capsules a day, providing 850 mg; each bottle holds 60 capsules, a 30-day supply. The brand says it is gluten-free, sugar-free, lactose-free, soy-free and non-GMO, with no magnesium stearate. The capsules are gelatin, so FLOW is not vegetarian or vegan. The offer reached through the official link is a subscription: a first bottle where you pay only shipping, followed by a monthly charge until you cancel. This page sets out what the official store states, how FLOW is meant to be taken, and what to know about its ingredients. It is an editorial overview, not a hands-on test, and nothing here is medical advice.
How it works
Nitric oxide is a molecule the lining of the blood vessels makes to help them relax and widen, which supports blood flow. The body makes it from the amino acid arginine, and it can turn citrulline into arginine — so citrulline supplements are used to support nitric oxide production. The brand says nitric oxide declines with age and that citrulline is more effective than arginine at raising it. FLOW's citrulline is described as plant-based, made by fermenting organic watermelon — the fruit citrulline is named after — and organic spinach, which is also naturally rich in nitrates. Vitamin C from acerola is added, which the brand says increases citrulline absorption, and pine bark extract for its circulatory effects and to sustain nitric oxide production. The brand links better blood flow to energy, cardiovascular health and arousal in both men and women. It does not publish trials of the finished capsule.
Who it's for
FLOW is marketed to adults over 40 of any gender who want to support circulation, energy and intimacy as nitric oxide production declines with age. The brand says it is made in the USA by a family-owned manufacturer, with independent laboratory testing. It is not a substitute for medical care. Erection problems can be an early sign of heart disease, diabetes or high blood pressure, so they are worth discussing with a doctor. Because citrulline can lower blood pressure, it should not be combined with erectile dysfunction medicines such as sildenafil or tadalafil, nitrate heart medicines, or blood pressure medicines without medical advice.
Usage
The official store says to take two capsules daily, morning or evening, for the 850 mg dose. It also suggests an additional two capsules before intimacy, which uses a bottle faster than 30 days. The brand advises consulting a healthcare professional first if you have a medical condition, are pregnant, breastfeeding or trying to conceive, are under 18, or take medication — especially blood pressure medication.
Common questions
Frequently asked questions
What is The 20?
The20 is the brand behind FLOW Nitric Oxide Booster®, a citrulline capsule marketed to support circulation, energy, sleep and intimacy for men and women.
What is in FLOW?
L-citrulline from organic watermelon and spinach, vitamin C from organic acerola cherries and pine bark extract, at 850 mg per two-capsule dose.
How do I take FLOW?
Two capsules daily, morning or evening. The brand also suggests an extra two capsules before intimacy.
Is FLOW a subscription?
Yes. The offer through the official link is a subscription: a first bottle for the cost of shipping, then a monthly charge until you cancel. The store says you can cancel anytime.
Is FLOW for men or women?
The brand says FLOW is formulated for everyone, and suggests it for adults over 40.
Can I take FLOW with Viagra or Cialis?
Not without your doctor's advice. Citrulline can lower blood pressure, and combining it with these medicines, nitrates or blood pressure tablets may cause it to drop too far.
Is FLOW vegetarian?
No. The capsules are made from gelatin.
Is there evidence that FLOW works?
We found no published trial of FLOW itself. Citrulline and pine bark have small studies for circulation and mild erection problems.
What is the refund policy?
The brand says you can return the unused portion within 364 days of purchase for a full refund of the purchase price, less shipping and handling.
How many capsules are in a bottle?
60 capsules, a 30-day supply at two a day.
Does FLOW contain soy or sugar?
No. The brand says it contains no soy, sugar, lactose, gluten or magnesium stearate.
Should I see a doctor about erection problems?
Yes. They can be an early sign of heart disease, diabetes or high blood pressure, and effective treatments are available.
Before you go
What happens when you click the button?
You go to the official store
The button opens the seller's official page. This site never takes your payment details.
Check the details there
Price, availability, shipping and the guarantee are set by the seller and can change, so confirm them before you order.
The seller handles your order
Checkout, delivery and any refund request go through the seller and its customer support, not through us.
See The 20 on the official site.
Prices, availability and current return terms are set by the seller and can change — check them on the official site before you buy.
Clinical reviewer
James Willson, PharmD
Clinical Pharmacist · Health content reviewer · Six years’ professional experience
James Willson is a clinical pharmacist with a Doctor of Pharmacy (PharmD) qualification and six years of professional experience in clinical pharmacy and the review of health-related information.
He reviews health and wellness content on Wellness Center USA for accuracy, clarity, appropriate terminology and responsible presentation of product information — including ingredient details, usage instructions, precautions and references to scientific research, where applicable.
His goal is to help readers understand health and wellness information clearly, tell product claims apart from established evidence, and make better-informed decisions.
Editorial note
Information on this page reflects manufacturer statements, which are attributed as such, and our own research. It is provided for informational purposes and is not medical advice.
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