Semax vs Selank: Russian Nootropic and Anxiolytic Peptides
Two intranasal peptides developed in Russia with overlapping but distinct profiles. Semax leans cognitive, Selank leans anxiolytic — but both carry the same evidence caveats.
Semax and Selank are both products of Soviet-era and post-Soviet Russian peptide research, developed at the Institute of Molecular Genetics in Moscow. Both are intranasal peptides, both are approved in Russia, and both have been studied extensively in Russian-language medical journals with limited Western replication. They're often mentioned together in online nootropic circles, but they do quite different things.
Quick comparison
| Semax | Selank | |
|---|---|---|
| Structure | Heptapeptide (7 amino acids) — fragment of ACTH(4-10) with a Pro-Gly-Pro tail | Heptapeptide (7 amino acids) — analog of tuftsin with a Pro-Gly-Pro tail |
| Primary mechanism | Upregulates BDNF and NGF; modulates dopaminergic and serotonergic signaling | Modulates GABA, serotonin, and enkephalins; immune system effects |
| Primary effect | Cognitive — focus, memory, stroke recovery | Anxiolytic — without sedation or dependence |
| Route | Intranasal spray | Intranasal spray |
| Russian approval | Yes (stroke, optic nerve disease) | Yes (generalized anxiety disorder) |
| Western approval | None | None |
| Human studies | Moderate — mostly Russian stroke and cognitive trials (👥 human) | Moderate — Russian GAD and neurasthenia trials (👥 human) |
Semax in brief
Semax is a synthetic heptapeptide derived from the 4-10 fragment of adrenocorticotropic hormone (ACTH), with a proline-glycine-proline C-terminal extension added for metabolic stability. It's approved in Russia for ischemic stroke recovery, optic nerve conditions, and (in a lower dose) attention and memory concerns. Its mechanism is broad: it upregulates BDNF (brain-derived neurotrophic factor) and NGF (nerve growth factor) in the hippocampus and cortex, modulates the dopaminergic and serotonergic systems, and shows neuroprotective effects in animal models of ischemia. Human stroke trials in Russia report improved neurological recovery with Semax added to standard care (👥 human). Read the full Semax review.
Selank in brief
Selank is a synthetic analog of tuftsin, a naturally occurring tetrapeptide from immunoglobulin G, with the same Pro-Gly-Pro stabilizing tail as Semax. It's approved in Russia for generalized anxiety disorder and neurasthenia. Its main effect is anxiolytic, reported in Russian clinical studies to be comparable to benzodiazepines but without the sedation, cognitive impairment, or dependence liability. The mechanism involves enkephalin metabolism, GABA-ergic modulation, and serotonergic effects. It also has documented immunomodulatory properties (it enhances interferon production), a legacy of its tuftsin origin. Read the full Selank review.
Overlap and differentiation
Both peptides share the Pro-Gly-Pro stabilizing tail, both are given intranasally, and both show broad effects across anxiety, mood, cognition, and neuroprotection in Russian studies. Where they diverge: Semax's primary utility is cognitive — users typically describe it as a focus and mental-endurance enhancer, consistent with its BDNF upregulation and ACTH-derived structure. Selank's primary utility is anxiolytic — users describe it as taking the edge off anxiety without fogginess. Some Russian protocols combine them for broad-spectrum mood and cognitive support.
Evidence caveats
Almost all clinical trials for both peptides have been conducted in Russia, published in Russian-language journals, and not independently replicated in Western clinical settings. This isn't automatically disqualifying — Russian pharmacology has legitimate historical strength — but it means Western regulators have no basis on which to approve these compounds, and pharmacokinetic data are limited. Neither is FDA, EMA, or MHRA approved. Both are sold in grey markets labeled "research use only" with the usual caveats about purity, sterility, and dose verification.
Side-effect profile
Both are reported to have exceptionally clean acute safety profiles in the Russian literature — no sedation, no dependence, no withdrawal, no meaningful cognitive impairment. Mild nasal irritation from the delivery spray is the most common complaint. Long-term human safety data (multi-year) are unavailable.
Which should you choose?
Both are Russia-approved only, and neither is approved in the US, EU, UK, AU, or CA. If your research interest is cognitive enhancement, post-stroke recovery, or focus, Semax has the more relevant literature. If your research interest is anxiety, mood, or stress, Selank has the more relevant literature. The honest caveat for both: the evidence base is moderate, concentrated in one country, and not independently replicated at scale in the West.
Sources
- Gusev E.I. et al. "Semax in prevention of disease progression and development of exacerbations in patients with cerebral ischemia." Zh Nevrol Psikhiatr Im S S Korsakova. PubMed 18379529
- Kolomin T. et al. "The temporary dynamics of inflammation-related genes expression under tuftsin analog Selank action." Mol Immunol, 2014. PubMed 24859790
- Zozulya A.A. et al. "The efficacy of Selank in anxiety-asthenic disorders." Zh Nevrol Psikhiatr Im S S Korsakova, 2008. PubMed 18577961
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