Semax
Semax is a synthetic peptide of seven amino acids, developed in Russia. It is based on a fragment of ACTH, a hormone made by the pituitary gland, but it lacks ACTH's hormonal effects. Outside Russia it is sold as an unregulated 'research' peptide. Most of the clinical evidence comes from small Russian studies.
Approval status
Not approved by the FDA or EMA, and not part of any FDA-approved drug. In a 2026 review for a US advisory committee, FDA staff found too little evidence of benefit or safety and advised against letting pharmacies compound it, noting that many clinical reports are only in Russian. In July 2026 the committee voted 8–5 to recommend allowing it anyway, according to news reports; the vote is not binding, and FDA has not made a final decision.29
What it’s used or studied for
- Human studies
Recovery after ischemic stroke, in Russian trials. FDA did not assess them because the full reports are only in Russian.245
- Human studies
Optic nerve diseases, in a small Russian study where it was added to standard treatment.6
- Human studies
Migraine and trigeminal nerve pain, in one small uncontrolled study. FDA judged that it did not relieve pain in most participants.2
- Human studies
Motor neuron disease (ALS): an open Russian study saw no effect on the disease itself, but better quality-of-life scores.7
- Animal & lab only
Rodent studies report brain-protective, blood-thinning, pain-relieving and antidepressant-like effects.2
Each label shows how strong the evidence is: an approved use, human studies, animal or lab studies only, or a popular claim with no published studies. Being studied is not the same as being proven safe or effective.
Side effects
Most published studies did not report on side effects. FDA found one consumer report of eye pain and burning after semax nasal drops bought online, and no human safety data for injection.2
Cautions
- FDA flagged a possible bleeding risk, especially for people prone to bleeding or taking blood thinners, because semax had anticoagulant effects in studies.2
- In mice, semax strengthened the effect of amphetamine on brain dopamine. FDA notes its potential for abuse has not been studied.2
- FDA raised concerns about impurities and immune reactions, especially for injected products.2
- A Belgian medicines lab found semax in seized, unlabeled products sold online.8
Sources
- PubChem: Semax, ACTH(4-7)-Pro-Gly-Pro (CID 9811102)
- FDA briefing document: Semax-related bulk drug substances, Pharmacy Compounding Advisory Committee, July 2026
- Deigin VI et al. Development of peptide biopharmaceuticals in Russia. Pharmaceutics 2022 (review)
- Gusev EI et al. Semax in the acute period of hemispheric ischemic stroke. Zh Nevrol Psikhiatr 1997 (in Russian)
- Gusev EI et al. Efficacy of semax at different stages of ischemic stroke. Zh Nevrol Psikhiatr 2018 (in Russian)
- Polunin GS et al. Semax in optic nerve disease. Vestn Oftalmol 2000 (in Russian)
- Serdiuk AV et al. Semax in patients with motor neuron disease. Zh Nevrol Psikhiatr 2007 (in Russian)
- Vanhee C et al. Cognitive-enhancing research peptides in seized pharmaceutical preparations. Drug Test Anal 2020
- STAT news: FDA advisory panel narrowly rejects compounding of one peptide, backs two others (July 24, 2026)
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