Nootropics Index - Save on smarter supplements
Nootropics>Peptides, proteins & enzymes>Semax
Peptides, proteins & enzymes

Semax

Semax (ACTH(4-7)-PGP)

Semax is a synthetic peptide studied mainly in neurological clinical settings. Small healthy-volunteer studies show brain-imaging changes, not established focus or memory benefits. Compare the exact peptide form, concentration and delivery device before comparing prices; human safety remains insufficiently characterized.

SyntheticClinical ResearchLimited Human EvidencePopulation Specific EvidencePregnancy CautionLactation CautionLong Term Safety Unknown
Updated October 2026/5 min read/6 citations
Reviewed by the NootropicsIndex editorial team.Method: prioritize cited human research and official safety or regulatory sources; compare retailer-listed prices without endorsing products.Affiliate disclosure
01

What is it?

What Semax is

4

Semax is a seven-amino-acid synthetic peptide, commonly identified as ACTH(4-7)-PGP. Free-base Semax, its acetate salt and modified derivatives should not be assumed to be the same product.

Evidence versus nootropic marketing5
The 2018 healthy-volunteer experiment compared 14 people receiving intranasal Semax with 10 receiving placebo. It measured resting brain-network activity, not everyday learning, work output or a validated memory improvement.

Clinical populations differ from healthy shoppers

2

A 110-person post-stroke rehabilitation study reported increased plasma BDNF and improvements in functional outcomes. Its clinical population and rehabilitation setting limit extrapolation to healthy-adult cognitive enhancement.

A second imaging study is still a surrogate

6

A 2020 study examined resting functional connectivity in 52 healthy participants across Semax, Selank and placebo groups. Brain-network differences do not by themselves demonstrate a practical nootropic benefit.

02

Names, aliases and forms

Common NameSemax
Research CodeACTH(4-7)-PGP
Peptide SequenceMet-Glu-His-Phe-Pro-Gly-Pro
AbbreviationMEHFPGP
Pubchem Cid9811102
03

Mechanisms of action

Animal mechanisms have limited predictive value

3

Rat focal-ischemia research found altered immune- and vascular-related gene expression after Semax. This is an injury-model mechanism result, not clinical evidence that a healthy user will think more clearly.

04

Potential effects and evidence map

Human evidence includes small imaging studies in healthy volunteers and condition-specific rehabilitation research. Imaging changes and plasma BDNF measurements are not proof of better memory or productivity. The available studies do not establish a general healthy-adult benefit or a routine long-term regimen.

Effect domainMagnitudeGrade
Cellular / long-term brain support2
CumulativeConfidence: Low

A post-stroke study reported functional and BDNF changes. These condition-specific findings do not establish healthy-adult brain longevity.

Note 110 participants in rehabilitation settings; broader efficacy cannot be inferred.

1/5
C
Memory / learning5
UnknownConfidence: Low

Small healthy-volunteer imaging experiments show brain-network changes, but do not establish a meaningful memory or learning benefit.

Note A surrogate imaging outcome is different from improved cognitive performance.

0/5
D
05

Typical dosages and timing

Post-stroke study26000 mcg/day

The post-stroke study used the displayed daily amount in two 10-day courses separated by 20 days. This is a description of a clinical study, not a recommended dose or cycle for healthy people. No typical healthy-adult dose is presented here.

06

Timing & effect horizon

Effect horizonUnknown
Unknown
Study window2Cumulative
10 days
What timing measurements actually mean5

In the 2018 imaging study, measurements occurred 5 and 20 minutes after administration. Those measurement times are not established onset or duration of a useful cognitive effect.

07

Safety, side effects and risk profile

Why risk is unknown and unscored4
The FDA 2026 evaluation found too little clinical safety information to characterize Semax. Missing human pharmacokinetics and sparse adverse-event reporting leave no reliable numeric estimate. Unknown does not mean harmless.
Nasal-label cautions1
Russian labeling reports possible mild nasal irritation with prolonged use and lists pregnancy, breastfeeding, acute psychosis, anxiety-associated disorders and convulsion history as contraindications. It also discourages co-administration with local nasal vasoconstrictors. These are label-specific cautions, not measured incidence rates.
Evidence uncertainty4
Confidence: Low

Human safety is insufficiently characterized; the overall risk remains unscored rather than being interpreted as low.

Unscored
D
Legal / regulatory risk4
Confidence: Low

U.S. compounding and approval status is distinct from Russian labeling; a retail listing does not establish local eligibility.

Unscored
D
Pregnancy / lactation caution1
Confidence: Low

The Russian nasal-drop labeling lists pregnancy and breastfeeding among contraindications.

Unscored
C
Interaction risk4
Confidence: Low

FDA identified a possible bleeding concern from reported antithrombotic effects, especially with other medicines that increase bleeding risk. Its frequency is unknown.

Unscored
D
08

Interactions and cautions

Bleeding-risk uncertainty4

FDA noted a potential bleeding concern, particularly alongside medicines that increase bleeding risk, based on reported antithrombotic properties. This is a precaution with uncertain clinical incidence, not a quantified interaction rate.

09

Legal and regulatory status

U.S. regulatory context4

U.S. source review, October 18, 2026: the FDA staff briefing prepared for July 2026 described Semax free base and acetate as outside FDA-approved drug products and proposed against 503A listing. This historical staff proposal is not a final decision or a worldwide ban. The source does not establish current compounding or import eligibility; requirements differ by jurisdiction.

10

How it compares

Concentration is not the delivered dose1

Russian nasal-drop labels distinguish 0.1% from 1% products: a tenfold concentration difference. A percentage alone does not specify the amount delivered by a spray pump or the total amount in a bottle. Compare concentration, bottle volume and amount per actuation separately.

11

Practical buying and quality notes

  • Separate ready-made nasal drops or sprays from vials requiring additional preparation. Compare the stated peptide identity and delivered amount, not a vial price against a spray price. Missing quantity fields cannot support a meaningful price-per-milligram comparison.4
  • Check formulation-specific storage instructions, batch identity and testing. For nasal sprays, delivered-dose consistency and microbial quality matter; a purity percentage alone does not establish finished-product quality.4
12

FAQ

How long does Semax last, and is there a proven cycle?

5

The imaging studies only describe short observation windows. They do not establish the duration of a perceived cognitive benefit or a repeat-use cycle for healthy adults.

Is there a recommended Semax dose for healthy adults?

2

The source set does not establish one. A clinical rehabilitation regimen or a foreign nasal-drug label cannot be converted into a general nootropic recommendation.

13

References

  1. RLS Encyclopedia of Drugs. Semax nasal drops 0.1% and 1% prescribing-information page.
  2. The efficacy of Semax in the treatment of patients at different stages of ischemic stroke. Zh Nevrol Psikhiatr Im S S Korsakova. 2018.
  3. The peptide Semax affects expression of genes related to immune and vascular systems in rat brain focal ischemia: genome-wide transcriptional analysis. BMC Genomics. 2014.
  4. FDA. Evaluation of Semax-related bulk drug substances. Pharmacy Compounding Advisory Committee briefing, July 23-24, 2026.
  5. Lebedeva et al. Effects of Semax on the Default Mode Network of the Brain. 2018.
  6. Panikratova et al. Functional Connectomic Approach to Studying Selank and Semax Effects. 2020.
Note

This page is informational and summarizes available evidence. It is not medical advice, a recommendation, or a substitute for guidance from a qualified clinician.