Semax is a synthetic peptide developed in Moscow in the 1980s to protect and support the brain. In Russia it is a registered medicine, prescribed as nasal drops after strokes, for memory and attention problems, and for optic nerve disease. In the West it is better known as a nootropic, a compound people use hoping to sharpen focus and memory.
Because Semax is given in the nose, it skips the digestive system and may reach the brain more directly. This guide covers what Semax is, how it works, its potential benefits, side effects, and its legal status after the FDA's July 2026 advisory vote.
What Is Semax?
Semax is a heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. The first four amino acids are ACTH(4–7), a fragment of adrenocorticotropic hormone. The Pro-Gly-Pro tail protects it from rapid breakdown in the body.
Full-length ACTH tells the adrenal glands to release cortisol. The fragment Semax is built on does not, so Semax does not act as a stress hormone.
It was developed at the Institute of Molecular Genetics of the Russian Academy of Sciences and has been on Russia's List of Vital and Essential Drugs since 2011. In Russian medicine it is used for:
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Recovery after ischemic stroke and brain injury
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Memory and attention problems, including in older adults
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Optic nerve disease, such as glaucoma-related damage
How Semax Works
Semax acts on several brain systems at once. Most of this comes from animal and cell research.
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BDNF and neuroplasticity: raises brain-derived neurotrophic factor and its receptor, TrkB, in the hippocampus. BDNF helps nerve cells survive, grow and form new connections, which underpins learning and memory.
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Protection under stress: in models of low oxygen and reduced blood flow, Semax limited nerve cell death and changed the brain's protein and gene activity toward repair.
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Dopamine and serotonin: modulates both systems in rodents, which may relate to effects on motivation and mood.
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Inflammation: lowered inflammatory signaling after experimental stroke.
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Enkephalins: inhibits enzymes that break down the body's natural opioid peptides.
Potential Benefits of Semax
Focus, Learning and Memory
Semax's effect on BDNF and dopamine is the main reason it is linked to focus and memory. Russian clinical use for attention and memory problems, and a 2018 fMRI study showing changes in brain network activity in healthy volunteers, support interest here. Large controlled trials in healthy people are lacking.
Brain Protection and Recovery
This is Semax's best-supported use. Russian clinical studies report better neurological recovery after ischemic stroke. A 2018 study of 110 stroke patients found Semax raised BDNF levels, and higher levels tracked with better early rehabilitation.
Mood and Stress
Animal studies show Semax reduces stress-related behavior and affects dopamine and serotonin. Some users report steadier mood under pressure. Human evidence for mood effects is limited, and Selank is the Russian peptide more often studied for anxiety.
Blood Flow to the Brain
Experimental research suggests Semax supports blood vessel function and blood flow in the brain after injury. Claims about better endurance or performance in healthy athletes have not been tested.
Side Effects of Semax
Semax is generally reported as well tolerated in Russian clinical use. Most side effects relate to the nasal route.
Common
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Nasal irritation, dryness or mild burning
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Changes in the appearance of the nasal lining in some users
Less Common
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Mild rises in blood glucose have been noted in some people with diabetes, so blood sugar should be monitored.
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Headache, irritability or trouble sleeping, mostly in user reports.
Serious Effects
No consistent reports of serious toxicity, organ damage or dependence appear in the published literature. Long-term safety data outside Russia are limited.
Legal Status of Semax
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Russia and CIS countries: a registered prescription medicine, in clinical use since the 1990s.
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United States: not FDA approved. It was removed from the FDA's Category 2 list in April 2026. On July 24, 2026, the FDA's compounding advisory committee recommended adding Semax to the list compounding pharmacies may use, for cerebral ischemia, migraine and trigeminal neuralgia. The vote is advisory, and compounding is not permitted until the FDA completes formal rulemaking.
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European Union and UK: not authorized as a medicine.
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Anti-doping: Semax is not named on the World Anti-Doping Code list. Athletes should confirm its status with their anti-doping agency, since rules change.
Conclusion
Semax has a longer clinical track record than most nootropic peptides, with decades of use in Russia for stroke recovery, cognitive problems and optic nerve disease. Its effects on BDNF and brain protection give a plausible basis for that use.
The main limitation is that nearly all human research comes from Russia, and evidence for cognitive enhancement in healthy people is thin. The July 2026 FDA advisory vote could open a regulated US pathway, but Semax is not an approved drug in the US.
Semax FAQ
Is Semax the same as Selank?
No. Both come from the same Russian institute and share a Pro-Gly-Pro tail, but Semax is based on an ACTH fragment and is used for cognition and stroke, while Selank is based on tuftsin and is used for anxiety.
Is Semax legal in the US?
It is not FDA approved. An FDA advisory committee recommended it for compounding in July 2026, but compounding is not allowed until the FDA finalizes that through rulemaking.
Disclaimer
This article is for educational and informational purposes only. Semax is not approved by the FDA. Information here reflects Russian clinical practice and published research and is not a recommendation for use. Nothing here is medical advice. The Peptide Library is operated in connection with ZenoPeps. Research products are not intended for human consumption.
References
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Koroleva SV, Myasoedov NF. Semax as a universal drug for therapy and research. Biology Bulletin, 2018.
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Sudarkina OY, et al. Brain protein expression profile confirms the protective effect of the ACTH(4–7)PGP peptide (Semax) in a rat model of cerebral ischemia–reperfusion. International Journal of Molecular Sciences, 2021.
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Gusev EI, et al. Efficacy of Semax in the treatment of patients at different stages of ischemic stroke. Zhurnal Nevrologii i Psikhiatrii, 2018.