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Animal data onlyNot FDA approved

P21 dosage

Also known as: P021 · P-21 · Peptide 021 · Ac-DGGL(A)G-NH2 · CNTF peptide mimetic

Updated 43 sources

Every P21 protocol on file, 10 in all, labelled by where each number came from.

Calculate with P21P21 overview

P21 dosage by goal

Grouped by goal. Each protocol shows the amount, how often, cycle and rest as the source states them, with every titration step.

Intranasal4

Intranasal, originator vendor

Amount
1 to 4 mg
How often
Once daily
Route
Nasal, nasal spray

Note: Start at 1 mg a day and raise slowly to 2 to 4 mg for a stronger acute effect. This is Ceretropic's old advice, quoted on a blog. The same blog says some people find 500 mcg is plenty.

Intranasal, vendor reply on Reddit

Amount
1 to 3 mg
How often
Daily, starting at 1.5 mg
Route
Nasal, nasal spray

Note: A vendor rep on r/Nootropics gave this range and said most of its customers use P21 by nose rather than by injection.

Intranasal, common range

Amount
500 to 1,000 mcg
How often
Once daily
Route
Nasal, nasal spray
Cycle
4 to 6 weeks

Note: Marketed for nose-to-brain delivery; how much reaches the brain in people is unknown.

Intranasal, user reports

Amount
500 to 1,000 mcg
How often
Once or twice daily
Route
Nasal, nasal spray

Note: Users report 500 mcg a day, 1 mg a day, 500 mcg twice a day and 1 mg twice a day. The one detailed log at 1 mg twice daily turned sour by day 3 (lethargy, brain fog, low mood) and the writer planned to drop to 500 mcg.

Subcutaneous4

Subcutaneous, conservative

Amount
100 mcg
How often
Once daily
Route
SubQ, vial (powder)
Cycle
4 to 6 weeks, then off

Note: The lowest common starting point. Extrapolated from rodent work, not tested in people.

Subcutaneous, standard

Amount
200 to 300 mcg
How often
Once daily
Route
SubQ, vial (powder)
Cycle
4 to 6 weeks, then off

Note: A mid-range vendor protocol with no human dose-finding behind it.

Subcutaneous, 5 days a week

Amount
500 mcg
How often
Monday to Friday, mornings
Route
SubQ, vial (powder)

Timing: Morning.

Note: Built on a 10 mg vial mixed with 2 mL of bacteriostatic water. The guide itself calls it a research convention, not a validated dose.

Subcutaneous, user step-ups

Amount
300 to 1,000 mcg
How often
Once daily, raised every day or two
Route
SubQ, vial (powder)

Timing: Morning.

Note: One user went 500, then 750, then 1,000 mcg over three days and felt nothing definite after a week. Another went 300 to 500 to 1,000 mcg, used a 5 mg vial in about 10 days and planned a 4 to 6 week run.

Other protocols: injected2

Most cited range

Amount
500 to 1,000 mcg
How often
Once daily
Route
SubQ, vial (powder)
Cycle
4 to 8 weeks, with time off

Timing: Morning, to avoid sleep disruption.

Note: The broader range in circulation is 100 mcg to 2 mg a day, and new users are pointed to 250 to 500 mcg. The guide traces every figure to vendor copy and forums. Also used by nose.

App self-reports, per injection

Amount
200 to 400 mcg
How often
Once daily, per the same site's protocol table
Route
SubQ, vial (powder)

Note: Most common logged bucket among six PeptIQ app users; all logs fall between 100 and 400 mcg.

Doses shown are what sources report, labelled by origin. Not medical advice.

P21 dosage chart by vial size

Units to draw for the doses sources cite most, at every vial size and water volume.
P21: concentration and U-100 syringe units for each vial size and water volume
WaterStrength200 mcgdose, units300 mcgdose, units500 mcgdose, units
5 mg vial
2 mLCompetitor guide2.5 mg/mL80.08 mL120.12 mL200.2 mL
2.5 mLCompetitor guide2 mg/mL100.1 mL150.15 mL250.25 mL
10 mg vial
2 mLCompetitor guide5 mg/mL40.04 mL60.06 mL100.1 mL
50 mg vial
2 mLCompetitor guide†25 mg/mL0.80.008 mLunder 1 unit1.20.012 mL20.02 mL
2.5 mLCompetitor guide†20 mg/mL10.01 mL1.50.015 mL2.50.025 mL
100 mg vial
2 mLCompetitor guide†50 mg/mL0.40.004 mLunder 1 unit0.60.006 mLunder 1 unit10.01 mL
2.5 mLCompetitor guide†40 mg/mL0.50.005 mLunder 1 unit0.80.008 mLunder 1 unit1.30.013 mL
Units are on a U-100 insulin syringe (100 units = 1 mL). U-50 and U-30 barrels read the same units.† Water volume sourced for a different vial size. The math is exact either way.Water volumes from

Doses shown are what sources report, labelled by origin. Not medical advice.

Calculate with this peptideYour vial, your water, your dose: P21 in syringe units, with the math shown.

Mixing P21

Diluent: Bacteriostatic water

Water volumes sources use: 2 mL, 2.5 mL

The solution should be clear. For nasal use some people mix the powder into a spray bottle with bacteriostatic water or saline instead; Ceretropic shipped empty spray bottles with its vials.

P21 dosage questions

What dose of P21 do people use?

There is no tested human dose. Guides and forums cluster at 500 mcg to 1 mg once a day, with a wider spread of 100 mcg to 2 mg. Ceretropic, the first seller, advised 1 mg a day by nose, rising to 2 to 4 mg. Injection guides start at 100 to 300 mcg.

How do I mix a 10 mg vial?

One guide adds 2 mL of bacteriostatic water to a 10 mg vial for 5 mg/mL, so 500 mcg is 10 units on a U-100 insulin syringe. Our calculator does the math for any vial and volume.

What doses did the animal studies use?

Most studies mixed P021 into mouse or rat food. In one long mouse study the chow held 60 nmol per gram, about 162 nmol per mouse per day, for up to 18 months. A brain-injury study gave the parent peptide at 50 nmol a day for 30 days.

Sources for these doses

15 sources, each checked by date. Record updated Oct 24, 2026. Numbers are restated in our own words and labelled by where they came from.

Vendor guide4

  1. Adamax and P21: two new nootropic peptides to watch closelyjaycampbell.com, via a news report · checked Oct 24, 2026
  2. P21 reconstitute for nasal spray (vendor reply)r/Nootropics, via a community post · checked Oct 24, 2026
  3. P21 peptide product pageVendor product page · checked Oct 24, 2026
  4. P21 solution (archived 2014)Ceretropic (Wayback Machine) · checked Oct 24, 2026

Competitor guide2

  1. P21 (P021) reportoutliyr.com · checked Oct 24, 2026
  2. P21 protocol guidepathtopeptides.com · checked Oct 24, 2026

Community-reported9

  1. Semax, P21, Selank nasal sprays: how much can I take?r/Peptides · checked Oct 24, 2026
  2. Substance amounts I use for productivity (comment)r/Nootropics · checked Oct 24, 2026
  3. Peptide nasal spray conversion kit (comment)r/DecentralizedSci · checked Oct 24, 2026
  4. P21 and N-acetyl Semax experience logr/Nootropics · checked Oct 24, 2026

Back to the full P21 page for side effects, storage, stacks and legal status.