What is Semax?

Semax is a synthetic ACTH(4-7) analog extended with Pro-Gly-Pro, best known as an intranasal neuropeptide developed and studied largely in Russia and neighboring research programs. [1][2][3]

Its interest comes from neuroprotection, stress-response, immune-gene, and cognition-adjacent mechanisms rather than from a U.S. prescription-drug pathway. [1][2][3]

Semax, ACTH(4-7)-PGP, and related modified Semax products are not interchangeable because amidation, acetylation, salts, and formulation can change stability and exposure. [1][2][3]

What Semax is investigated for

Semax evidence is grouped by practical use case and intranasal route context. Each use case separates confidence, human evidence, animal or mechanistic support, and the practical takeaway.

Cognition and focus

Intranasal

44% Preliminary

Cognition and focus claims remain preliminary and mostly preclinical in the cited literature. [6][3][7][10]

Human evidence

Major-market controlled human cognition evidence is not established in the reviewed sources. [6][3][7][10]

Animal / mechanistic evidence

Rodent studies connect Semax with dopaminergic, serotonergic, behavioral, and coordination biology relevant to focus and cognition claims. [6][3][7][10]

Neuroprotection

Intranasal

42% Preliminary

Neuroprotection is the strongest Semax biology signal, but it remains preliminary for human outcomes. [1][2][4][5]

Human evidence

Clinical neuroprotection certainty is not established in major-market approvals or the cited literature. [1][2][4][5]

Animal / mechanistic evidence

Rat ischemia studies report transcriptome, immune-gene, and protein-expression changes consistent with neuroprotective activity. [1][2][4][5]

Stroke recovery support

Intranasal

34% Limited

Stroke recovery has animal-model support, not established rehabilitation-treatment evidence. [1][2][4][5]

Human evidence

Human stroke-recovery outcome evidence is not established in the cited literature. [1][2][4][5]

Animal / mechanistic evidence

The stroke-recovery rationale comes from cerebral ischemia-reperfusion rat models and related brain-expression studies. [1][2][4][5]

Mood and stress support

Intranasal

30% Limited

Mood support is a separate but lower-confidence animal-behavior signal. [8][3][6]

Human evidence

Controlled human mood or stress-disorder outcomes for Semax are not established in the cited literature. [8][3][6]

Animal / mechanistic evidence

Rodent stress and early-life fluvoxamine-exposure models report antidepressant-like, antistress, and neurochemical effects. [8][3][6]

Evidence snapshot

Overall confidence

Emerging

55%

Semax has limited-human support from regional intranasal use and a broader animal neurobiology record. Major-market cognition or stroke-recovery evidence remains limited. [1][2][3][4]

Overall confidence is a page-level composite, not an average; it weighs evidence quality, route/molecule match, and practical limitations.

55%

Human evidence

Emerging

Human support is mostly regional and indication-specific rather than a broad FDA-style clinical program. That keeps cognition and neuroprotection confidence limited. [1][2][3][4]

34%

Animal / preclinical

Limited

Animal and transcriptome studies support neurobiological plausibility across neurotrophin, oxidative-stress, and ischemia-response pathways. [1][2][3][4]

55%

Mechanism support

Emerging

Semax is investigated around neurotrophin, immune-gene, oxidative-stress, and ischemia-response pathways. The mechanism suggests brain-stress modulation rather than a proven general nootropic effect. [1][2][3][4]

Forms & administration

Semax is tracked as an intranasal peptide. Spray-style protocols are separate from injectable peptide dosing and from modified Semax analogs. [10][1][2]

Nasal spray

Dosing & protocols

The notes below separate published trial design from commonly discussed cosmetic or compounded-use patterns. They are educational context only, not a prescription or product instruction.

Typical Range

Common intranasal protocols usually use 300-600 mcg per day. [10][1][2]

Frequency

Common intranasal schedules use 1-2 sessions daily. [10][1][2]

Timing Considerations

Morning or afternoon timing is the common anchor for focus-oriented use. [10][1][2]

Cycle Length

Common intranasal blocks run 4-12 weeks before changing dose or combining with Selank. [10][1][2]

What to expect

First few days

Intranasal Semax may feel like sharper daytime alertness, easier task initiation, or steadier focus during work or study blocks. [1][2][3][4][10]

Weeks 2-4

Intranasal focus, task consistency, mood resilience, and stress response may become steadier across routine days. [1][2][3][4][10]

After stopping

Perceived focus and stress-resilience changes may soften over routine days after intranasal Semax use ends. [1][2][3][4][10]

Safety profile

Semax safety is mainly intranasal and neuroactive: nasal irritation, headache, sleep disruption, overstimulation, and product formulation matter. [1][2][3][4]

Common side effects

Nasal irritation [1][2][3][4]
Headache [1][2][3][4]
Sleep disruption [1][2][3][4]

Cautions

Anxiety / overstimulation [1][2][3][4]
Neurologic disease [1][2][3][4]
Formulation variability [1][2][3][4]

What we don't know

Long-term repeated intranasal use, drug interactions, pregnancy, and pediatric safety remain poorly characterized in major-market sources. [1][2][3][4]

Who Semax is not for

Route-specific avoid and medical-review notes:

Pregnancy or breastfeeding
Pregnancy or breastfeeding warrants medical review or avoidance for Semax. [1][2][3][4]
Unstable psychiatric symptoms
Unstable psychiatric symptoms warrants medical review or avoidance for Semax. [1][2][3][4]
Seizure disorder without clinician review
Seizure disorder without clinician review warrants medical review or avoidance for Semax. [1][2][3][4]

Drug & supplement interactions

Documented interactions are separated from theoretical or route-specific cautions.

Theoretical interactions

Stimulants / nootropics
Stimulants, high-caffeine products, racetams, or other alertness stacks can compound overstimulation or insomnia; this is a theoretical neuroactive caution. [1][2][3][4]
Sedatives / anxiolytics
Benzodiazepines, alcohol, sleep aids, or sedating supplements can blur anxiety, focus, and alertness tracking; this is a theoretical neuroactive caution. [1][2][3][4]
Other nasal sprays
Decongestant, steroid, or irritating nasal sprays can add dryness or change intranasal tolerability; this is a route-specific caution. [1][2][3][4]

Pairing notes

Commonly included in these stacks

Semax / Selank

Semax / Selank is a two-neuropeptide stack built around focus, cognitive stress response, and anxiety-oriented support. Semax supplies the ACTH-fragment cognitive and neuroprotective rationale, while Selank supplies the tuftsin-analog anxiolytic and stress-resilience rationale.

SemaxSelank

Regulatory status

United States

In the U.S. as of 2026-06-21, Semax is not FDA-approved for the reviewed intranasal route. FDA compounding safety-risk materials flag this substance or close naming variant, so the 503A row should be read as a safety-risk bucket, not approval. [16][10][11][14][15]

Route	FDA drug approval	503A compounding
Intranasal	Not Approved Semax is not FDA-approved as an intranasal drug in the U.S. for the reviewed use; research-market supply and compounding are separate from FDA approval. [10][11][14][15]	Flagged FDA safety-risk materials flag Semax for immunogenicity, aggregation, peptide impurities, and no or limited proposed-route safety information. This is a 503A compounding safety-risk bucket, not FDA drug approval. [16][10][11][14][15]

Intranasal

FDA drug approval

Not Approved

Semax is not FDA-approved as an intranasal drug in the U.S. for the reviewed use; research-market supply and compounding are separate from FDA approval. [10][11][14][15]

503A compounding

Flagged

FDA safety-risk materials flag Semax for immunogenicity, aggregation, peptide impurities, and no or limited proposed-route safety information. This is a 503A compounding safety-risk bucket, not FDA drug approval. [16][10][11][14][15]

International

EU/Europe, UK, Canada, and Australia require product-specific checks in EMA/MHRA, Health Canada, and TGA registers. Research-market, supplement, or compounded availability should not be treated as therapeutic approval in those markets. [17][18][19][20]

Sports & competition

WADA S0 can apply to non-approved pharmacological substances that are not otherwise named. Tested athletes should not treat Semax intranasal route as athlete-cleared without sport-specific review. [12][10][11][14][15]

How it works

Semax is an ACTH-fragment analog discussed around neurotrophin signaling, immune-gene expression, oxidative-stress response, and ischemia-related brain pathways. In plain terms, the biology asks whether it can shift stressed neural tissue toward protection and recovery signaling. [1][2][3][4]

Intranasal delivery matters because nasal tolerability, formulation, and central-nervous-system exposure shape the practical claim. Animal transcriptome and protein-expression findings support mechanism plausibility, but they do not establish reliable human focus, mood, or stroke-recovery outcomes. Human use therefore stays tied to route-specific trials, dosing, and safety data. [1][2][3][4]

Research gaps & open questions

What the current literature has not yet settled about Semax:

A key evidence gap is major-market randomized human cognition trials. [1][2][3][4]

A key evidence gap is formulation-specific intranasal pharmacokinetics. [1][2][3][4]

A key evidence gap is combination-level Semax/Selank safety and timing evidence. [1][2][3][4]

Common questions

Is Semax FDA-approved in the United States?

No. Semax is not FDA-approved in the U.S. for intranasal drug use, and FDA lists Semax with compounding safety concerns. [10][11][1][2][16][14]

Is Semax a stimulant?

No. It is not a classic stimulant; intranasal Semax is discussed around ACTH-fragment neurobiology, with sleep and overstimulation cautions. [10][11][1][2]

Is Semax the same as NA-Semax-Amidate?

No. NA-Semax-Amidate is a modified derivative with separate route, exposure, and evidence questions. [10][11][1][2]

Myths & misconceptions

Myth

Intranasal use makes Semax automatically safe.

Reality

The route can be convenient, but local tolerability and systemic neuroactive effects still need review. [1][2][3][4]

Myth

Semax plus Selank is a proven stack.

Reality

The pairing is common in discussions, but combination-level evidence is separate from component evidence. [1][2][3][4]

History & discovery

Semax came from ACTH-fragment design: a synthetic ACTH(4-7)-PGP analog intended to separate central nervous system activity from broader corticosteroid effects. That origin explains its neuroprotection and intranasal positioning. That distinction keeps the origin story tied to evidence strength, route, and product identity rather than broad clinical certainty. [1][2][3][4]

The recognizable Semax sequence made it a defined ACTH-fragment analog rather than a general stimulant. Later work connected it with neurotrophin, immune-gene, and ischemia-response pathways. [1][2][3][4]

Rat ischemia-reperfusion studies broadened the mechanism story into transcriptome and protein-expression changes. Those experiments shaped research interest without proving human focus or stroke-recovery outcomes. [1][2][3][4]

Published research 12 studies

[1]

Semax, an analog of ACTH((4-7)), regulates expression of immune response genes during ischemic brain injury in rats.

Mol Genet Genomics, 2017 Jun. animal.

[2]

Novel Insights into the Protective Properties of ACTH((4-7))PGP (Semax) Peptide at the Transcriptome Level Following Cerebral Ischaemia-Reperfusion in Rats.

Genes (Basel), 2020 Jun 22. animal.

[3]

Semax, synthetic ACTH(4-10) analogue, attenuates behavioural and neurochemical alterations following early-life fluvoxamine exposure in white rats.

Neuropeptides, 2021 Apr. animal.

[4]

Brain Protein Expression Profile Confirms the Protective Effect of the ACTH((4-7))PGP Peptide (Semax) in a Rat Model of Cerebral Ischemia-Reperfusion.

Int J Mol Sci, 2021 Jun 8. animal.

[5]

[The Peptide Drug ACTH(4-7)PGP (Semax) Suppresses mRNA Transcripts Encoding Proinflammatory Mediators Induced by Reversible Ischemia of the Rat Brain].

Mol Biol (Mosk), 2021 May-Jun. animal.

[6]

Semax, an ACTH(4-10) analogue with nootropic properties, activates dopaminergic and serotoninergic brain systems in rodents.

Neurochem Res, 2005 Dec. review.

[7]

Influence of the N-terminus acetylation of Semax, a synthetic analog of ACTH(4-10), on copper(II) and zinc(II) coordination and biological properties.

J Inorg Biochem, 2016 Nov. review.

[8]

Antidepressant-like and antistress effects of the ACTH(4-10) synthetic analogs Semax and Melanotan II on male rats in a model of chronic unpredictable stress.

Eur J Pharmacol, 2024 Dec 5. animal.

[9]

Morphofunctional State of the Large Intestine in Rats under Conditions of Restraint Stress and Administration of Peptide ACTH((4-7))-PGP (Semax).

Bull Exp Biol Med, 2021 Jan. animal.

[10]

Drugs@FDA/openFDA query for Semax

U.S. Food and Drug Administration. database query.

[11]

Compounding and the FDA: Questions and Answers

U.S. Food and Drug Administration. official guidance.

[12]

The 2026 List of Prohibited Substances and Methods

World Anti-Doping Agency. regulatory.