Semax: what the research shows

Semax (Met-Glu-His-Phe-Pro-Gly-Pro) is a synthetic analog of the adrenocorticotropin fragment ACTH(4-10), studied mainly in Russia and given intranasally in published work. It is not an FDA-approved drug, and its clinical evidence comes almost entirely from Russian studies.[1][2]

Russian clinical studies in stroke

A 2018 study of 110 patients after ischemic stroke, split into early and late rehabilitation groups with and without semax (two 10-day courses of 6,000 mcg/day), reported higher plasma BDNF and better Barthel index recovery in the semax subgroups.[3] An earlier 1997 study gave semax to 30 patients in the acute period of hemispheric ischemic stroke, compared them with 80 conventionally treated controls, and reported “some influence” on the rate of neurological recovery.[4] These were published in a Russian neurology journal by Russian groups, and the 2018 study does not describe blinding or placebo control in its abstract.[3] We read the full Russian text in our semax stroke teardown.

Animal data

In rats, a single intranasal dose of semax (50 mcg/kg) increased hippocampal BDNF protein about 1.4-fold and trkB activation about 1.6-fold, alongside improved conditioned avoidance learning.[1]

Regulatory status

No FDA-approved drug product contains semax; a Drugs@FDA search returns no approved application.[2] FDA lists semax (heptapeptide) among substances previously placed in compounding category 2 whose nominations were withdrawn, citing aggregation and impurity risk and stating it has “no, or limited, safety-related information for proposed routes of administration.”[5]

Update, October 28, 2026: HHS made public a draft enforcement-discretion policy that lists semax among six peptides (the others are BPC-157, epitalon, KPV, MOTS-c and TB-500). HHS says it does not intend to take enforcement action against state-licensed pharmacies, federal facilities or licensed physicians that compound these peptides under 10 conditions.[6] For semax, Appendix B names semax free base, for intranasal use only.[6] The conditions include bulk powder from an FDA-registered facility with a certificate of analysis, one listed active ingredient per product, reporting of serious adverse events and a patient-specific prescription.[6] HHS calls the document a draft, open to comment on regulations.gov (Docket No. HHS-OASH-2026-0496) until 2 weeks after its October 30, 2026 Federal Register publication (November 13, 2026, per regulations.gov), and says it is not binding and may be revisited if a safety signal or quality problem arises.[6] This is not an FDA approval: compounded drugs are not reviewed by FDA for safety or effectiveness, and the policy records that FDA’s drug center recommended against listing semax.[6] For what it does and doesn’t change, see our FDA peptide policy explainer. This summary is not legal advice.

What is not known

There are no independent, placebo-controlled trials outside Russia and no Western regulatory review of efficacy or safety.[3][5]

References

Dolotov OV, et al. Semax, an analog of ACTH(4-10) with cognitive effects, regulates BDNF and trkB expression in the rat hippocampus. Brain Res. 2006;1117(1):54-60. PMID 16996037. https://pubmed.ncbi.nlm.nih.gov/16996037/. Checked October 15, 2026.
U.S. Food and Drug Administration. Drugs@FDA: FDA-Approved Drugs database (searched by ingredient name via the openFDA drugsfda endpoint). https://www.accessdata.fda.gov/scripts/cder/daf/. Checked October 15, 2026.
Gusev EI, et al. [The efficacy of semax in the treatment of patients at different stages of ischemic stroke]. Zh Nevrol Psikhiatr Im S S Korsakova. 2018;118(3 Vyp 2):61-68. (In Russian.) PMID 29798983. https://pubmed.ncbi.nlm.nih.gov/29798983/. Checked October 15, 2026.
Gusev EI, et al. [Effectiveness of semax in acute period of hemispheric ischemic stroke (a clinical and electrophysiological study)]. Zh Nevrol Psikhiatr Im S S Korsakova. 1997;97(6):26-34. (In Russian.) PMID 11517472. https://pubmed.ncbi.nlm.nih.gov/11517472/. Checked October 15, 2026.
U.S. Food and Drug Administration. Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks (Category 2 of the bulk substances nominated under sections 503A or 503B). Content current as of April 22, 2026. https://www.fda.gov/drugs/human-drug-compounding/certain-bulk-drug-substances-use-compounding-may-present-significant-safety-risks. Checked October 15, 2026.
U.S. Department of Health and Human Services, Office of the Secretary. Notice of availability: “Enforcement Discretion Policy Regarding 503A Compounding Using Certain Peptide Bulk Drug Substances” (FR Doc. 2026-22192, RIN 0910-ZD94, docket HHS-OASH-2026-0496). Filed for public inspection October 28, 2026, 11:15 AM ET; published in the Federal Register October 30, 2026 (91 FR 68526). The notice says written comments can be submitted via regulations.gov on Docket No. HHS-OASH-2026-0496 until 2 weeks after publication, and regulations.gov lists the comment deadline as November 13, 2026, 11:59 PM ET. The notice calls the policy a draft, says compounded drugs “are not FDA-approved,” and says the policy “is not binding on HHS or the public.” https://www.federalregister.gov/documents/2026/10/30/2026-22192/enforcement-discretion-policy-regarding-503a-compounding-using-certain-peptide-bulk-drug-substances. Policy document (Appendix A lists BPC-157, epitalon, KPV, MOTS-c, semax and TB-500; numbered conditions 1–10; Appendix B gives the permitted routes for each and states that FDA’s Center for Drug Evaluation and Research recommended against listing each one and that the Pharmacy Compounding Advisory Committee voted in favor): https://www.hhs.gov/sites/default/files/hhs-503a-peptide-enforcement-discretion-policy-appendix-b.pdf. Checked October 28, 2026.

This page summarizes published research and regulatory documents. It is not medical advice and does not recommend using, sourcing, or dosing any of these substances.