Semax is a synthetic heptapeptide (Met-Glu-His-Phe-Pro-Gly-Pro) derived from adrenocorticotropic hormone (ACTH) fragment 4-10, with an added Pro-Gly-Pro sequence for metabolic stability. Molecular weight is approximately 813.88 g/mol (formula C37H51N9O10S). Discovered in Russia during the 1980s as part of government-funded neuropeptide research, it is approved in Russia and Ukraine for the treatment of ischemic stroke, cognitive disorders, encephalopathy, and optic nerve atrophy. Despite its ACTH origin, Semax does not activate adrenal corticosteroid production, acting selectively on brain-specific pathways.
Category: Nootropic / Neuroprotective. Evidence rating: D (animal/preclinical only).
Clinical status: Approved in Russia and Ukraine for stroke and cognitive disorders; not approved elsewhere
Semax is a brain-selective heptapeptide (Met-Glu-His-Phe-Pro-Gly-Pro, MW ~813.88 g/mol) that crosses the blood-brain barrier via intranasal absorption. It increases brain-derived neurotrophic factor (BDNF) expression and upregulates trkB receptors, supporting neuroplasticity and long-term memory…
Research base: 0 registered clinical trials and 3 indexed publications reference Semax.
Safety considerations: Generally favorable safety profile with uncommon mild side effects and no dependence potential; No significant hormonal effects despite ACTH-fragment origin — brain-selective mechanism reduces systemic side effects; Administered intranasally — mild nasal irritation possible; proper spray technique recommended.
Reviewed by the PeptideAtlas Editorial Team. Last reviewed: 2026-08-12.
Related peptides: Cerebrolysin, Pinealon, Cortagen.
Compare: Semax vs Cerebrolysin, Semax vs Pinealon, Semax vs Cortagen.
No. Although semax is derived from an ACTH fragment, the specific 4-10 fragment used does not activate adrenal corticosteroid production. It is designed to cross the blood-brain barrier while avoiding hormonal effects of ACTH. The brain-selective mechanism of action makes it particularly suited for cognitive and stress-related applications without systemic hormonal disruption.
Yes. Semax is approved in Russia and Ukraine for indications including ischemic brain stroke, encephalopathy, optic nerve atrophy, and cognitive disorders such as dementia. It is not approved in any Western country. Most published human data originate from Russian clinical registries and journals.
Most commonly through intranasal spray (1% solution), which allows direct absorption through nasal mucosa into the bloodstream and brain. Typical doses range from 0.5-3 mg per day divided into morning and sometimes afternoon doses. For cerebrovascular patients, daily doses of 200-6000 mcg over 5-14 day courses have been used. Injection protocols use lower doses due to higher bioavailability but…
Many users report improved focus and mental clarity within the first few hours of the first dose. fMRI studies confirm altered brain activation patterns within 5-20 minutes of intranasal administration. Cognitive and mood benefits deepen within days to weeks. A single intranasal dose at 16 mcg/kg lasts approximately 24 hours.
No. Semax has no demonstrated dependence potential. Users do not develop tolerance requiring escalating doses. However, it is generally recommended to establish cycling protocols (e.g., 2-4 weeks on, 1 week off) as a precaution, similar to other nootropic peptides.