P021, P-21, Peptide 021, Ac-DGGL-adamantylglycine-NH2
A small synthetic peptide made from four amino acids of ciliary neurotrophic factor (CNTF), a protein that keeps nerve cells alive, capped with a bulky adamantane group so it resists breakdown and reaches the brain. In mice and rats it raised BDNF, a brain growth signal, and the birth of new nerve cells in the hippocampus, the brain’s memory center.
None of these uses is approved, and none has been tested in people. Here is what each claim rests on.
Animal: cell or animal studies only.
Every compound’s uses, by body system: evidence map, and by condition: conditions A to Z.
Category 2 is FDA’s list of bulk substances that may present significant safety risks in compounding. The 503A bulks list adds substances that pharmacies may compound with. Advisory committee votes are advice; FDA makes the final decision. Sport status follows the WADA Prohibited List in force since January 1, 2026; athletes should confirm with their anti-doping organization. Checked October 5, 2026. Status outside the US checked October 7, 2026 against EMA, MHRA, Health Canada and TGA records. By country: EU, UK, Canada, Australia. Status of every compound.
P21 copies the part of ciliary neurotrophic factor (CNTF), a protein that keeps nerve cells alive, that its inventors mapped as the active site. In mice and rats it raised BDNF, a growth signal for brain cells, and damped leukemia inhibitory factor, a signal that holds back new nerve cells. More new neurons survived in the hippocampus, and lower activity of GSK-3β, an enzyme that adds phosphate to tau, the protein that clumps in Alzheimer’s, went with less tau buildup.
AnimalMainly from cell and animal studies; not shown in people.
Its direct target on cells hasn’t been identified. The developers report that it enters the brain in rats, but whether it reaches the human brain, or changes anything there, has never been tested.
No dose has been tested in any person. Public guides quote anything from 100 mcg to 2 mg a day, disagree by twentyfold, and none of them cites a study of P21 in people.
No set cycle, shown over 26 weeks
The ways P21 is most often run, each tagged with where it comes from.
Not tested in any study. The amounts quoted online trace back to sellers and user reports, not to animal or human data.
Several guides mention nasal use. No study has given P21 to a person by any route.
Community use is injection under the skin with rotating sites, or a nasal spray. The animal studies mostly mixed it into food; no study has tested injection or nasal use in people.
No published guidance. Skip the missed dose and take the next one on schedule; don’t double up.
Learning and short-term and spatial memory improved, with more new nerve cells maturing in the hippocampus (Li 2010).
AnimalIn 22–24-month-old rats it reduced the age-related decline in learning and memory, restored new nerve-cell growth and raised BDNF (Bolognin 2014).
AnimalLess abnormal tau, lower soluble amyloid-β and better memory than untreated model mice, with treatment started at 9–10 months of age (Kazim 2014).
AnimalNothing is known. It is sold for memory, focus and brain aging, but no study has tested it in anyone.
CommunityUnknown in people
No one has been given P21 in a published study, so its side effects and their rates are unknown.
Trouble sleeping or feeling overstimulated (user reports)
Mentioned in a public guide; no study has looked. Users move the dose earlier in the day or stop.
Loss of appetite, nausea and weight loss (seen with the full CNTF protein in people)
Not seen in mice given P21 for months. Track weight and appetite, and stop if they change.
Injection-site pain, redness or infection (unregulated vials)
Use sterile technique. Spreading redness, heat or pus needs medical care.
Hives, swelling of the face or throat, or trouble breathing after a dose: stop and get medical help. A hot, spreading red injection site with fever needs urgent care.
The side effects people ask about most, answered one by one. Each answer says where it comes from.
Community: reported by users, not studied. Precaution: a concern that follows from how it works or from a related drug, not measured. Animal: seen only in animal studies. No data: no human safety data. A side effect that hasn’t been reported can still happen, especially with long or high-dose use. Any of these across every compound: the side-effect finder.
No product label covers P21, so these come from human studies and from precautions based on how it works. Most important first.
Precaution: follows from how it works or from a related drug, and hasn’t been tested. This isn’t a complete list: a pharmacist or doctor can check a specific medicine or condition. Every documented interaction, by medicine: drug interactions.
What’s known about pregnancy, breastfeeding, kidney and liver problems, age and surgery. Where nothing has been studied, the row says so.
Precaution: not studied, so the caution follows from how it works or from a related drug. Ages are given as approved or studied; this site never gives doses for children. Across every compound: pregnancy, breastfeeding, kidney disease, liver disease, older adults and surgery.
Usually run on its own.
No published human studies of P21 turned up in our October 2026 review. The evidence note at the top of this page sums up what is known.
No ongoing trial of P21 is registered, and none has finished recently without publishing its results. Checked on ClinicalTrials.gov, October 7, 2026. Every compound: trials under way.
Everything known comes from cells, mice and rats, nearly all from the New York lab that designed P21, whose leader co-founded the company licensed to develop it. The animals mostly ate it in food for months; injections and nasal sprays, the ways it is used online, haven’t been studied. No person has received it in a published study, so the dose, effects and safety in people are unknown.
Sold as powder vials and premixed nasal sprays, both as unregulated research chemicals. Strengths vary between sellers and nothing checks them, so the amount in a vial or a spray is unknown. Vial Guide gives no mixing or dose figures for a compound no person has received in a published study.
Every compound side by side: the half-life chart and the storage chart.
Every compound’s numbers: the identifiers table.
Sold as P21 or P021 in powder vials and premixed nasal sprays. The published molecule is four amino acids plus an adamantane group, 578.7 g/mol; the cell-cycle protein p21 is unrelated. Nothing regulates identity, purity or sterility.
A small synthetic peptide made from four amino acids of ciliary neurotrophic factor (CNTF), a protein that keeps nerve cells alive, capped with a bulky adamantane group so it resists breakdown and reaches the brain. In mice and rats it raised BDNF, a brain growth signal, and the birth of new nerve cells in the hippocampus, the brain’s memory center.
P21 copies the part of ciliary neurotrophic factor (CNTF), a protein that keeps nerve cells alive, that its inventors mapped as the active site. In mice and rats it raised BDNF, a growth signal for brain cells, and damped leukemia inhibitory factor, a signal that holds back new nerve cells. More new neurons survived in the hippocampus, and lower activity of GSK-3β, an enzyme that adds phosphate to tau, the protein that clumps in Alzheimer’s, went with less tau buildup. Its direct target on cells hasn’t been identified. The developers report that it enters the brain in rats, but whether it reaches the human brain, or changes anything there, has never been tested.
Not approved as a drug in the US, the EU or anywhere else. No human trial has been registered; Phanes Biotech, co-founded by the peptide’s inventor, holds a worldwide license to develop it. Never nominated for pharmacy compounding, so it appears on none of FDA’s 503A or 503B bulk substance category lists (503A list updated May 14, 2026).
From community reports, not established: No dose has been tested in any person. Public guides quote anything from 100 mcg to 2 mg a day, disagree by twentyfold, and none of them cites a study of P21 in people. These are the amounts sources reference, not recommendations.
No product label covers P21, so these come from human studies and from precautions based on how it works. Pregnancy or breastfeeding: No human safety data exist. Mouse studies gave it through pregnancy and nursing to study the pups’ brains, not to test safety. Anyone with active or past cancer: It boosts BDNF and the growth of new nerve cells. Growth signals like these haven’t been tested in anyone with cancer, and no long-term cancer study exists. Anyone relying on product quality: Sold only as an unregulated research chemical, in vials and premixed sprays. Nothing checks that it contains the right molecule, at the stated amount, free of contamination.
Before mixing: Freezer (−20 °C) for long-term storage, kept dry and dark. After mixing: Fridge (2–8 °C) once in solution. This is common practice; no product label covers it.
Probably. Not named in the 2026 List. An unapproved compound still in preclinical development falls under S0 non-approved substances, banned at all times. As a growth factor mimic it could also be read as an S2.3 growth factor modulator, likewise banned at all times.
No published human studies turned up in our October 2026 review. The evidence note at the top of this page sums up what is known.
No data No human studies: no one has been given P21 in a published study, and no trial is registered.
Animal Never given to people by any route. Animal studies mostly gave it by mouth, in food; injection under the skin and nasal sprays are community routes no study has tested.
No study No data. No study has looked at P21 and alcohol together.
No study No study has combined them. No interaction is known, but none has been looked for.
No data There’s no label, no overdose data and no human dosing study. Call Poison Help (1-800-222-1222), or emergency services for severe symptoms.
For the protocol details
For how it works, who should avoid it and the limits of the evidence
For uses, the side-effect questions, special situations, trials, identifiers and status outside the US
Doses tagged Community come from public dosing guides and user reports, checked against at least two of them. Those sites aren’t named here because many of them sell peptides or earn commissions on them.