Semax

Synthetic ACTH-derived neuropeptide · Also known as ACTH 4-10 analog, Semax 0.1%, N-acetyl semax amidate (NASA)

What is semax?

A synthetic peptide based on a fragment of adrenocorticotropic hormone (ACTH 4-10) developed in Russia as a neuroprotective and nootropic agent. It is approved in Russia and Ukraine for stroke recovery and cognitive enhancement.

Semax was developed at the Institute of Molecular Genetics of the Russian Academy of Sciences in the late 1980s. It has been approved in Russia for clinical use since the 1990s for conditions including ischemic stroke, dyscirculatory encephalopathy, optic nerve atrophy, and cognitive impairment. Russian clinical studies include a 110-patient stroke rehabilitation trial showing elevated BDNF levels and improved functional outcomes. While it lacks FDA approval or large Western RCTs, it has decades of clinical use in Russia and a strong safety profile.

Key takeaway: Semax is one of the few nootropic peptides with regulatory approval (in Russia) and decades of clinical use for stroke recovery and cognitive enhancement.

Benefits & evidence

Cognitive enhancement Moderate confidence
Neuroprotection Moderate confidence
Stroke recovery support Moderate confidence
BDNF elevation Moderate confidence
Focus and mental clarity Preliminary confidence

How it works

Semax is derived from ACTH but engineered to isolate cognitive and neuroprotective properties while eliminating hormonal (adrenal) activity. It rapidly increases brain-derived neurotrophic factor (BDNF) expression in the hippocampus, which supports neuronal survival, synaptic plasticity, and memory formation.

It also modulates multiple neurotransmitter systems, including dopaminergic and serotonergic pathways, and inhibits enkephalin-degrading enzymes, prolonging the activity of endogenous neuropeptides. Additionally, Semax has shown anti-inflammatory effects in brain tissue and may influence gene expression related to immune and vascular function, which contributes to its neuroprotective effects in ischemic conditions.

Dosing information

Typical dosing protocol
Starting dose

200-400 mcg intranasal, 1-2x daily

Weeks 1-2
Maintenance dose

300-600 mcg intranasal, 1-2x daily

10-14 day cycles

Russian clinical guidelines use the 0.1% intranasal solution. Subcutaneous injection at 200-300 mcg daily is also used but has less clinical data behind it. Cycle 10-14 days on, then take a break. Consult your healthcare provider.

Side effects

Most side effects tend to improve as your body adjusts.

Nasal irritation or dryness Common
Nasal mucosa discoloration Uncommon
Headache Uncommon
Mild anxiety at higher doses Rare

Research (10 studies)

Therapeutic Peptides in Orthopaedics: Applications, Challenges, and Future Directions. Journal of the American Academy of Orthopaedic Surgeons. Global research & reviews · 2026