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PeptideLimited humanNot FDA approved

Semax

Semax

Last reviewed October 27, 2026 · 14 sources · Written for general readers · Compare with another compound →

The bottom line

Semax is a registered drug in Russia, but it is not approved in the United States. Online it is sold for focus, memory and brain protection, yet those claims rest mostly on rat studies and small Russian studies without strong controls. FDA staff found the proof of benefit and safety too thin, and although an advisory panel voted to allow compounding in July 2026, FDA has not acted on that vote.

Where the evidence stands

What it is

Semax is a lab made chain of seven amino acids. It is built from a piece of ACTH, a stress hormone, but it is designed not to act like the hormone.[1] It is a registered drug in Russia, where it is sold as nose drops.[2]

In the United States it is not an approved drug. Online sellers offer it as a nasal spray or injection, alone or mixed with selank, for anxiety, stroke, Parkinson's, Alzheimer's and other conditions, sometimes labeled for research use only.[2] FDA says it is often unclear whether these products were made by a licensed pharmacy.[1]

Name
Semax (Semax)
Other names
semax acetate, Met-Glu-His-Phe-Pro-Gly-Pro, ACTH(4-10) analog
Type
Peptide
Sequence
MEHFPGP
CAS number
80714-61-0
Formula
C37H51N9O10S
Molecular weight
About 813.9 g/mol

How it works

Scientists do not fully understand how semax works. FDA describes its effects as wide ranging and poorly explained.[1]

  • In normal rats, a single nasal dose raised BDNF, a growth factor that helps nerve cells survive and form connections, in the hippocampus, a memory area, within about an hour.[3][4]
  • In rats with a blocked brain artery, semax turned up genes for several of these growth factors.[5]
  • Lab work suggests it blocks enzymes that break down enkephalins, the body's own calming and pain relieving chemicals.[2]
  • Rat studies found it can slow blood clotting, and its main breakdown product, Pro-Gly-Pro, also has anticlotting effects.[1]
  • In rats, giving it in the nose put more of it in the brain than giving it into a vein. The body breaks it down quickly.[1]

Most of this comes from rodent studies by a small number of Russian research groups, so the picture is incomplete.

What the research shows

We keep animal and human evidence apart. A result in animals is a reason to study something in people, not proof that it works in people.

Animal and lab studies

Promising signals in rodents, with big gaps in safety testing

  • In rat stroke models, semax was linked to about 20% smaller areas of brain damage and fewer memory problems afterward.[1]
  • In rats, a single nasal dose raised BDNF levels in the hippocampus by up to 1.4 times, and treated rats learned an avoidance task better.[3]
  • In rats given a nerve toxin that damages dopamine cells, a model of Parkinson's, semax lessened the drop in movement and the rise in anxious behavior.[6]
  • It eased pain when injected into the belly of rats and mice, but not when given in the nose.[1]
  • In mice, it boosted the release of dopamine, a reward chemical, caused by amphetamine. FDA called this concerning because it could hint at misuse potential, which has not been studied.[1]
  • FDA found no standard toxicity studies, such as repeat dose or pregnancy safety studies.[1]

Limit: Animal results often fail to carry over to people, and key safety studies are missing.

Human studies

Small Russian studies, mostly without strong controls

  • A 1997 Russian study gave semax with usual care to 30 people with a recent stroke and compared them with 80 similar patients on usual care alone. The authors reported better recovery of movement and other brain functions, but the summary does not say patients were randomly assigned.[7]
  • A 2018 Russian study followed 110 stroke patients in rehabilitation for about 5 months. Those given semax had higher blood levels of BDNF and better scores for daily living tasks. The summary does not describe random assignment or a placebo.[8]
  • In a small study with no control group, 12 adults with migraine got a single nasal dose. Headache stopped in 4 of 12, and the other 8 said pain was less severe.[2]
  • In the same study, 16 people with typical trigeminal neuralgia, a severe facial nerve pain, had no change in their pain. Pain eased in 9 people with a related dental nerve pain, but attacks did not become less frequent or shorter overall.[2]
  • A 1999 Russian study treated 73 patients with lasting brain damage after oxygen loss with semax injections. The authors reported help for memory problems, but some patients showed abnormal bursts of brain electrical activity after an injection.[9]
  • A brain scan study of 52 healthy adults compared semax, selank and placebo. It found short term changes in how the amygdala, a fear and emotion center, linked with nearby brain areas, but it did not measure focus or memory.[10]
  • FDA also listed small studies in 19 healthy men, 32 adults with stomach ulcers, 120 teens with depression and 331 children with tics or Tourette syndrome. Most did not report side effects, and several were short meeting abstracts.[2]
  • FDA found no studies of how the human body absorbs or clears semax, and concluded the evidence of benefit was not enough for stroke, migraine or facial nerve pain.[2]

Limit: There are no large, well designed, placebo controlled trials of semax, and side effects were rarely reported.

Claims check

The most common claims about this compound, and what studies actually found. Verdicts rate the evidence, not whether you should use it.

Sharpens focus and memory

Only in animals

Rat studies show semax raises BDNF in memory areas and improves learning tasks.[3] FDA lists one small study in 19 healthy men, but we found no well designed human trial showing better focus or memory.[2] A brain scan study of 52 healthy adults saw short term changes in brain connections but did not test thinking skills.[10]

Speeds recovery after a stroke

Mixed results

Two Russian studies of 110 stroke patients each reported better recovery with semax plus usual care.[7][8] Neither summary describes random assignment or a placebo. FDA reviewed the evidence and called it insufficient.[1]

Raises BDNF, a brain growth factor

Mixed results

In rats, one nasal dose raised hippocampal BDNF protein by up to 1.4 times.[3] In 110 stroke patients, those given semax had higher blood BDNF over about 5 months, in a study without described randomization.[8] No controlled study shows that this rise helps healthy people.

Protects the brain from damage

Only in animals

In rat stroke models, brain damage areas were about 20% smaller with semax.[1] In a rat Parkinson's model, it lessened movement and anxiety problems.[6] No controlled human trial has shown brain protection.

Relieves migraine

Mixed results

Only one tiny study with no control group tested this. Of 12 adults given a single nasal dose, headache stopped in 4 and eased in 8.[2] Without a placebo group, this cannot show that semax caused the relief.

Eases nerve pain

No benefit in trials so far

In an uncontrolled study, 16 people with typical trigeminal neuralgia had no change in pain after semax, and attacks were no less frequent overall.[2] The authors concluded semax does not relieve pain on its own.[1]

Helps ADHD

Not tested

FDA searched and found no published studies supporting semax for ADHD.[1]

Known risks and side effects

  • Unknown product quality and immune reactions. Products sold online are not checked for purity. FDA found no test results for impurities, clumped peptide or bacterial toxins, and warns that these could trigger the immune system.[1][11]
  • Possible bleeding risk. Animal and early human lab data suggest semax slows clotting. FDA flagged this as a concern, especially with other drugs that raise bleeding risk.[2]
  • Abnormal brain electrical activity. In a 1999 study of 73 brain injured patients, some had abnormal bursts on brain wave tests after a semax injection, and the authors advised monitoring with the first injection.[9]
  • Reported eye injury. FDA received one report of eye pain and burning, with a hospital stay and symptoms lasting at least a year, after someone used semax nose drops bought online.[2]
  • Misuse potential and side effects unknown. A mouse study hinted semax may strengthen the dopamine effect of stimulants, and no one has tested its abuse potential.[1] Most human studies did not report side effects at all, so how often they happen is unknown.[2]

Regulatory status

Today: Semax is not FDA approved. FDA advisers voted 8 to 5, with 1 abstaining, to let pharmacies compound it, even though FDA staff advised against it.[12] The vote is not binding, and FDA had not acted on it as of the latest reports.[12][13]

  1. The 2026 WADA list took effect. It does not name semax. Its S0 ban covers drugs with no government approval for human use, and semax is approved in Russia, so athletes should ask their anti doping body.[14]
  2. FDA listed semax among substances once held in Category 2, its list of compounding safety risks, whose nominations were withdrawn.[11]
  3. FDA staff reviewed semax and found the evidence weighs against adding it to the list of ingredients pharmacies may use.[1]
  4. FDA's Pharmacy Compounding Advisory Committee voted 8 to 5, with 1 abstaining, in favor of adding semax.[12]

Sources

  1. U.S. Food and Drug Administration. FDA evaluation of semax and semax acetate for the 503A bulks list. Pharmacy Compounding Advisory Committee briefing document, meeting of July 24, 2026. FDA briefing document
  2. U.S. Food and Drug Administration. FDA presentations: emideltide, epitalon and semax. Pharmacy Compounding Advisory Committee meeting, July 24, 2026. FDA slides
  3. Dolotov 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 Res. 2006;1117(1):54-60. PMID 16996037
  4. Agapova TY, Agniullin YV, Shadrina MI, Shram SI, Slominsky PA, Lymborska SA, Myasoedov NF. Neurotrophin gene expression in rat brain under the action of Semax, an analogue of ACTH 4-10. Neurosci Lett. 2007;417(2):201-205. PMID 17353092
  5. Dmitrieva VG, Povarova OV, Skvortsova VI, Limborska SA, Myasoedov NF, Dergunova LV. Semax and Pro-Gly-Pro activate the transcription of neurotrophins and their receptor genes after cerebral ischemia. Cell Mol Neurobiol. 2010;30(1):71-79. PMID 19633950
  6. Levitskaya NG, Sebentsova EA, Andreeva LA, Alfeeva LY, Kamenskii AA, Myasoedov NF. The neuroprotective effects of Semax in conditions of MPTP-induced lesions of the brain dopaminergic system. Neurosci Behav Physiol. 2004;34(4):399-405. PMID 15341218
  7. Gusev EI, Skvortsova VI, Miasoedov NF, Nezavibat'ko VN, Zhuravleva EIu, Vanichkin AV. [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. PMID 11517472
  8. Gusev EI, Martynov MY, Kostenko EV, Petrova LV, Bobyreva SN. [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. PMID 29798983
  9. Alekseeva GV, Bottaev NA, Goroshkova VV. [Use of semax at a follow-up of patients with posthypoxic encephalopathy]. Anesteziol Reanimatol. 1999;(1):40-43. PMID 10199046
  10. Panikratova YR, Lebedeva IS, Sokolov OYu, Rumshiskaya AD, Kupriyanov DA, Kost NV, Myasoedov NF. Functional Connectomic Approach to Studying Selank and Semax Effects. Dokl Biol Sci. 2020;490(1):9-11. PMID 32342318
  11. U.S. Food and Drug Administration. Certain bulk drug substances for use in compounding that may present significant safety risks. Content current as of April 22, 2026. FDA
  12. Healio. FDA committee recommends looser restrictions for several peptides. July 24, 2026 (updated September 15, 2026). News report
  13. Fierce Pharma. Peptide adcomm Day 2: Emideltide voted down in panel's 1st peptide pushback. July 2026. News report
  14. World Anti-Doping Agency. World Anti-Doping Code International Standard: Prohibited List 2026. In force January 1, 2026. WADA 2026 List
Medical disclaimer

This page is educational information only. It is not medical advice and does not replace care from a licensed medical provider. Do not use this page to decide whether to take any substance. Talk to a licensed medical provider first.

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