P21_
Also known as P021
An experimental peptide studied for new brain cells and memory.
Common vial size is what vendors typically sell, not a recommendation. Enter your own vial in the calculator.
What is P21?
Plain language first. The technical label stays, but it never stands alone.Overview
P21 is a small peptide derived from CNTF, a natural nerve-growth factor. In plain terms: it is studied for growing new brain cells and protecting memory, but there is no human data.
What it's used for
An experimental peptide studied for growing new brain cells and protecting memory.
How does P21 work?
What it does in the body, and where.P21 is a small peptide derived from CNTF, a natural nerve growth factor, built to keep the growth-promoting activity while avoiding CNTF's side effects.
- 01It mimics a nerve growth factorPromoting the birth of new brain cells in the hippocampus, the region tied to memory formation.
- 02Mouse results were positiveIncluding in Alzheimer's models, which is the source of the interest.
- 03No human has ever taken it in a studyConfirmed by the Alzheimer's Drug Discovery Foundation. Everything claimed about it in people is extrapolation.
A schematic of the compound's mechanism, not a diagnostic image.
What else is it used for?
Each use below carries its own evidence level. Approved means regulators have cleared it for that purpose. Investigational means it is in trials. Early research means it is being studied and is not established.
- Growing new brain cells and protecting memoryResearch only
How much, and do you cycle it?
The range, and whether you take breaks.Research only, as studied. No established scheduleNo range
No published study has established how long to take this or whether a break is needed. Schedules quoted online come from vendors and forums, and different sources disagree.
How do I dose and price it?
Enter your vial and your dose. Pick a mix. We show the draw and the cost.The vial holds a fixed amount of drug. Adding more water does not make more drug, it just spreads it thinner, so you draw a bigger number on the syringe for the same dose.
Choose your mix
Measuring the water1 mL = one full 100-unit syringe.
Your draw
40 / 100 unitsHow do you store it?
Before mixing, and after.Dry powder in the freezer or fridge. Once mixed, fridge, and use within about a month.
Unmixed lyophilized P21 keeps for a long time cold. Once you add water the clock starts: most reconstituted vials hold up for roughly 28 to 30 days at fridge temperature. Keep it out of light, and do not freeze it after mixing.
What are the side effects and cautions?
Known cautions and warnings for this compound.Who should avoid it
- Pregnancy or breastfeeding
- Active cancer, as a precaution with anything that promotes tissue or blood-vessel growth
- Any prescription medicine you take regularly, without checking for interactions first
- Anyone who wants established safety data, because none exists for this compound in humans
Stop and get help
- Spreading hives, swelling of the face or throat, or trouble breathing, which can happen with any injection and is a medical emergency
- Redness, heat, or pus at the injection site, which can signal infection
- Any severe or unexpected symptom
- Anything unusual, since there is no known safety profile to compare it against
Common effects
- There is no human data.
- Redness, soreness, or a small bump at the injection site
- Beyond the above, unknown. There is no reliable human data on what this compound commonly causes
Where this page says nothing is established, that means nobody has studied it, not that a compound is safe.
Is P21 approved?
And where the numbers on this page come from.No. Not FDA-approved.
Sold for research use only. Not cleared for human consumption or medical use.
- DoseFrom research and community reports. No regulator has reviewed this dose.
- Vial sizeFrom what vendors typically list; not a recommendation.
- Reviewed22 July 2026
What else is like P21?
Others in Brain, mood and sleep, side by side.If you're weighing P21, it's worth reading Semax, Selank, and N-Acetyl Semax Amidate in the same class.
An experimental peptide studied for new brain cells and memory.
- Dose
- Research only
- How often
- As studied
A nasal spray for sharper focus, memory, and mental clarity.
- Dose
- 0.2 up to 0.6 mg per day
- How often
- 1-2x daily
A nasal spray that eases anxiety while keeping you clear-headed.
- Dose
- 0.25 up to 0.5 mg per day
- How often
- 1-2x daily
A longer-lasting version of Semax for focus and memory.
- Dose
- 0.2 up to 0.4 mg per day
- How often
- 1-2x daily
10What these words mean
Show glossary +
What these words mean
- Titrate
- Starting at a low dose and increasing it slowly over time so your body adjusts and side effects stay mild.
- Subcutaneous
- An injection just under the skin, into the fat layer, usually with a short, thin insulin needle.
- Intramuscular (IM)
- An injection into a muscle, using a longer needle.
- Reconstitution
- Mixing a powdered peptide with liquid (bacteriostatic water) so it can be drawn into a syringe.
- Bacteriostatic water
- Sterile water with a tiny amount of preservative, used to mix powdered peptides.
- Concentration
- How strong the mixed peptide is, in milligrams per milliliter (mg/mL). More water makes it weaker; less water makes it stronger.
- Units (on the syringe)
- The marks on an insulin syringe. 100 units equals 1 mL. They measure how much liquid you draw, not the dose in milligrams.
- mcg and mg
- Units of dose. 1 milligram (mg) equals 1,000 micrograms (mcg).
- GLP-1
- A natural gut hormone that lowers appetite and blood sugar. Drugs that copy it, like semaglutide, are used for weight loss.
- Growth hormone secretagogue
- A compound that nudges your body to release more of its own growth hormone, rather than injecting the hormone itself.
- Half-life
- How long a compound stays active in your body. A longer half-life means you inject less often.
- Peptide vs small molecule
- A peptide is a short chain of amino acids. A few items here (like MK-677 or methylene blue) are small molecules, not true peptides, but people use them the same way.
- Research only
- No approved dose or use in people. Sold for research and not reviewed by the FDA for safety or quality.
- Investigational
- Still being tested in clinical trials and not yet approved or legally sold for general use.
- Banned in drug-tested sport
- Prohibited by the World Anti-Doping Agency (WADA); using it can disqualify a competing athlete.
Last reviewed 22 July 2026