Semax
A synthetic peptide derived from a fragment of ACTH, developed in Russia and used there for stroke and cognitive indications. It is not approved in the US and independent human evidence is limited.
Quick take
- What it is: a synthetic peptide based on a fragment of the hormone ACTH, developed in Russia as a nootropic and neuroprotective agent.
- What people use it for: cognitive enhancement and focus; in Russia it is also used in stroke and other neurological settings.
- What we actually know: most evidence is from Russian and small studies; large independent human trials are lacking.
- Status: used clinically in Russia but not approved by the FDA or other major Western regulators.
What it is
Semax is a synthetic peptide developed in Russia, based on a short fragment of the hormone ACTH (adrenocorticotropic hormone) modified for stability. It was developed as a nootropic and neuroprotective agent and is used clinically in Russia, including in neurological care.1
Together with Selank, it is one of the Russian-developed neuropeptides used clinically there but not approved in the US or most other countries.
How it works
Semax is thought to act largely by increasing levels of brain-derived neurotrophic factor (BDNF) and related neurotrophins, and by influencing neurotransmitter systems and pathways involved in neuronal survival and plasticity.1,2 These mechanisms underpin both its claimed cognitive effects and its use in neuroprotection, though the human picture is not fully characterised.
What the evidence shows
Animal studies
Animal studies report neuroprotective and cognition-related effects and increases in neurotrophic markers such as BDNF, supporting the proposed mechanism.2
Human studies
Human data exist, including studies in ischaemic stroke and cognitive settings, but most are small or originate from Russian research groups, and large independent randomised trials are lacking. The reliability and size of its effects in people are therefore not well established outside that body of work.3
Dosages reported in the literature
Informational only. The figures below describe doses reported in studies and clinical use in Russia. They are not a recommendation or a prescription. Appropriate use, if any, should be determined by a qualified healthcare professional.
| Setting | Route | Reported range |
|---|---|---|
| Cognitive use (Russian clinical) | Intranasal | Low-concentration nasal solution, microgram-to-milligram daily ranges |
| Neurological / stroke (Russian clinical) | Intranasal / injection | Higher reported ranges in acute settings |
Because there are no large independent dose-finding trials, no range here should be read as established as safe or effective.
Safety & side effects
In reported clinical use, Semax is generally described as well tolerated, with few prominent side effects noted.3 However, there are no long-term controlled Western safety studies, so its full risk profile is not established.
As with any peptide sold outside a regulated supply chain, product purity and dose accuracy vary between sources, which is an added concern.
Legal & regulatory status
Semax is not approved by the FDA or other major Western regulators. It is used clinically in Russia, where it was developed, but that does not confer approval elsewhere.1 Its legal status for sale and use varies by country and changes over time.
References
- Eremin KO, Kudrin VS, Saransaari P, Oja SS, Grivennikov IA, Myasoedov NF, Rayevsky KS. Semax, an ACTH(4-10) analogue with nootropic properties, activates dopaminergic and serotoninergic brain systems in rodents. Neurochem Res. 2005;30(12):1493-1500. [PMID 16362768, doi:10.1007/s11064-005-8826-8]
- Dolotov OV, Karpenko EA, Inozemtseva LS, Seredenina TS, Levitskaya NG, Rozyczka J, Dubynina EV, Novosadova EV, Andreeva LA, Alfeeva LY, Kamensky AA, Grivennikov IA, Myasoedov NF, Engele J. Semax, an analog of ACTH(4-10) with cognitive effects, regulates BDNF and trkB expression in the rat hippocampus. Brain Research. 2006;1117(1):54-60. [PMID 16996037, doi:10.1016/j.brainres.2006.07.108]
- Gusev EI, Martynov MYu, 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;118(3 Vyp 2):61-68. [PMID 29798983, doi:10.17116/jnevro20181183261-68]