SemaxWhat the studies show
A seven-amino-acid fragment of the stress hormone ACTH, given as nasal drops in Russian stroke wards since the 1990s and never tested in a blinded trial.
5 min read · Mixed evidence · Updated November 2026
In short
- Name
- semax (sold by Progression Labs as Semax)
- Evidence
- Mixed evidence
- Bottom line
- Russian clinical studies in stroke compared against standard care rather than placebo, plus repeatable rat and cell work on BDNF; registered as a medicine in Russia, with no blinded trial anywhere.
Before you read this
This guide explains what published studies found. That is all it is.
It is not medical advice and it is not instructions for using anything. Where a dose appears, we are reporting what a named study gave the people or animals in it — a fact about the study, not an instruction to you.
The compounds here are not approved by the FDA for use in people and are sold for laboratory research only. A study tells you what happened to the subjects in it; it does not tell you what would happen to you. Talk to a doctor first.
What it is
Semax is a chain of seven amino acids (Met-Glu-His-Phe-Pro-Gly-Pro). The first four come from ACTH, the hormone that drives the adrenal glands. A stretch of ACTH known as ACTH 4-10 had been noticed in the 1970s to affect attention and learning in animals without any hormonal effect, and chemists at the Institute of Molecular Genetics in Moscow kept the active core of that stretch and attached Pro-Gly-Pro to protect it from breakdown 1. It is given as drops into the nose. Semax is registered in Russia as a medicine under that name, as nasal drops in two strengths: a weaker one for conditions including cognitive impairment after brain injury, and a stronger one for acute ischaemic stroke 1. It is not approved by the U.S. FDA or any Western regulator, and no clinical trial of it has been published outside Russia.
The studies below call this molecule semax. Progression Labs sells it as Semax; the guide uses the store's name and the papers use theirs.
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Stroke
The clinical use rests on studies led by Gusev and Skvortsova, neurologists in Moscow. A 1997 report in the Korsakov Journal of Neurology and Psychiatry followed patients in the first days of a hemispheric ischaemic stroke who were given semax nasal drops alongside standard care, and compared them with patients on standard care alone; the semax group had better neurological scores and more favourable EEG changes over the following weeks 2. A 2018 paper from the same group gathered experience across different stages of stroke, from the acute period to later rehabilitation, and again reported better functional recovery in treated patients 3.
The design matters. These were comparisons against standard care, not against a placebo spray, and the reports are in Russian-language journals with limited detail on how patients were allocated and whether anyone was blinded. In stroke, where recovery varies enormously from person to person, an unblinded comparison can show a difference that a blinded one would not, because the people scoring recovery know who got the drug. No independent group outside Russia has tried to reproduce the result, and the step that would settle it, a blinded trial against a placebo spray, has not been run in the decades since the first stroke report.
BDNF in rats
The best-documented laboratory finding is on BDNF, a growth factor neurons need to survive and form connections. A 2006 study in Brain Research gave rats semax into the nose and found that BDNF protein in the hippocampus rose within hours, together with its receptor TrkB 4. An earlier 2001 study had seen a similarly fast induction of neurotrophin genes when semax was added to rat glial cells in culture 5. A 2010 follow-up tracked BDNF and NGF gene expression over time in the rat hippocampus, frontal cortex and retina after nasal semax and found that the response differed by region and faded within a day 6.
This is a consistent thread across three studies and gives a plausible route by which the peptide could affect recovery after injury. It is also a long way from a person: a rise in BDNF in a rat hippocampus is a mechanism, not an outcome.
What is not known
There is no blinded, placebo-controlled trial of semax in any condition, in stroke or otherwise. There is no published safety database beyond Russian clinical use, and no pharmacokinetic study showing how much of a nasal dose reaches the human brain. The ACTH 4-10 idea that semax grew out of was studied in the West in the 1970s and then dropped, and semax itself has never been picked up by a drug company outside Russia. The registration in Russia means a national regulator accepted the studies above; it does not fill the gap those studies leave.
What these studies are, and aren't
Mixed evidence. Russian clinical studies in stroke compared against standard care rather than placebo, plus repeatable rat and cell work on BDNF; registered as a medicine in Russia, with no blinded trial anywhere.
Sources
- 1Ashmarin IP, Nezavibatko VN, Myasoedov NF, et al. A nootropic adrenocorticotropin analog 4-10-Semax (15 years experience in its design and study). Zhurnal Vysshei Nervnoi Deiatelnosti imeni I.P. Pavlova, 1997 (review).
- 2Gusev EI, Skvortsova VI, Miasoedov NF, et al. Effectiveness of semax in acute period of hemispheric ischemic stroke (a clinical and electrophysiological study). Zhurnal Nevrologii i Psikhiatrii imeni S.S. Korsakova, 1997.
- 3Gusev EI, Martynov MY, Kostenko EV, Petrova LV, Bobyreva SN. The efficacy of semax in the treatment of patients at different stages of ischemic stroke. Zhurnal Nevrologii i Psikhiatrii imeni S.S. Korsakova, 2018.
- 4Dolotov OV, Karpenko EA, Inozemtseva LS, et al. Semax, an analog of ACTH(4-10) with cognitive effects, regulates BDNF and trkB expression in the rat hippocampus. Brain Research, 2006.
- 5Shadrina MI, Dolotov OV, Grivennikov IA, et al. Rapid induction of neurotrophin mRNAs in rat glial cell cultures by Semax, an adrenocorticotropic hormone analog. Neuroscience Letters, 2001.
- 6Shadrina M, Kolomin T, Agapova T, et al. Comparison of the temporary dynamics of NGF and BDNF gene expression in rat hippocampus, frontal cortex, and retina under Semax action. Journal of Molecular Neuroscience, 2010.
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