Semax: what the Russian clinical work actually tested

The short answer

• Semax is a seven-amino-acid fragment analogue of ACTH, specifically ACTH(4-7) with a Pro-Gly-Pro tail added to slow its breakdown.
• It is approved in Russia as intranasal drops: 1% drops for acute ischaemic stroke, and 0.1% drops for cognitive and neurological conditions including optic nerve disease and, in children aged 7 and over, minimal brain dysfunction or ADHD.
• Judged by Western evidence standards, the tier for stroke and cognitive uses is Early human data. For subcutaneous injection and for cognitive enhancement in healthy people it is Preclinical only.
• Every human study used the nose. There is no published human data for subcutaneous injection, which is the form most North American buyers get.
• Its own Russian label contraindicates anxiety disorders, acute psychiatric states and a seizure history. Community material marketing it for mood and anxiety routinely leaves that out.

So what is Semax peptide used for, officially?

The honest way to answer “what is Semax peptide used for” is to read the label rather than the forums. Semax is registered by Peptogen in Moscow in two strengths, and the indications differ.

The 1% nasal drops are for acute ischaemic stroke as an adjunct. The label runs 6,000 to 12,000 micrograms a day for moderate stroke and 12,000 to 20,000 micrograms a day for severe stroke, in four to five divided doses over 10 days. Those are large numbers, and they belong to a hospital setting.

The 0.1% drops carry a wider set: cognitive and memory disorders in the context of cerebrovascular disease and transient ischaemic attack (800 to 8,000 micrograms daily), recovery after traumatic brain injury or neurosurgery, optic nerve disease (600 to 900 micrograms daily), fatigue and “adaptation”, and minimal brain dysfunction or ADHD in children aged 7 and over (200 to 400 micrograms daily for 30 days).

There is no North American label. In the US, Semax is not on the 503A Bulks List. It was formerly in 503A Category 2 and came off when the nominators withdrew. At the Pharmacy Compounding Advisory Committee meeting on 24 July 2026, FDA proposed that Semax free base and acetate not be added, and the committee voted 8 to 5 with one abstention in favour of inclusion anyway. As of September 2026 no rulemaking has followed, so it remains outside the lawful bulk substance list. In Canada it has no DIN and was named among unauthorized injectable peptides seized from an online seller in a Health Canada advisory dated 1 August 2025.

What the trials actually looked like

This is where the picture thins out.

Acute stroke. The foundational study, Gusev 1997, compared 30 patients given Semax with 80 patients on conventional treatment. It is not described as randomised. The authors reported faster regression of neurological deficits and judged 12 mg a day best for moderate stroke and 18 mg a day for severe. A 1999 companion paper was a retrospective immunobiochemical comparison. No placebo-controlled, blinded trial with mortality or modified Rankin Scale endpoints could be located.

Post-stroke rehabilitation. Gusev 2018 studied 110 patients split into early and late rehabilitation groups, each further divided into Semax and no-Semax subgroups, with the allocation method unclear from the abstract. Semax patients showed higher plasma BDNF and better Barthel scores at 6,000 micrograms a day across two 10-day courses.

Healthy attention and memory. A 1997 review and a 1996 study of 19 healthy men on intranasal Semax, reporting improved attention task performance. Small, old, surrogate, never replicated.

ADHD. Despite the Russian paediatric label indication, no ADHD trial appears in PubMed. FDA’s review located only paediatric meeting abstracts, with no adverse event reporting.

Five problems recur here. The papers are mostly Russian-language with short English abstracts, and FDA’s July 2026 evaluation excluded seven clinical papers for that reason. Controls are frequently historical or “conventional therapy” groups without described randomisation or blinding. Endpoints lean on EEG mapping, evoked potentials and plasma BDNF instead of functional outcomes. The developers, at the Institute of Molecular Genetics and Peptogen, appear as co-authors across much of the work. And no Semax trial is registered on ClinicalTrials.gov, so selective reporting cannot be checked.

None of that proves Semax does nothing. It means the effect size and the safety profile are unknown by current standards.

The BDNF story, and why it is weaker than it reads

Semax is often marketed as a “BDNF peptide”. That comes from rodent work: intranasal Semax raised BDNF protein and trkB phosphorylation in rat basal forebrain and hippocampus within hours, and altered NGF and BDNF gene expression. Specific, saturable binding sites were reported in rat basal forebrain membranes, though no receptor target has been identified.

The problem with carrying that across to humans is measurement. Most circulating BDNF in people is stored in and released from platelets, so a plasma BDNF rise is not proof of a brain BDNF rise. Animal work does show blood and brain BDNF can correlate, but aerobic exercise alone raises peripheral BDNF, which makes it a poor marker inside an unblinded rehabilitation trial where activity levels differ between groups.

Other mechanisms have rodent or in vitro support only: increased striatal serotonin turnover and potentiated amphetamine-induced dopamine release, inhibition of enkephalin-degrading enzymes in human serum at around 10 micromolar, and anticoagulant effects described in Russian animal studies. Two small resting-state fMRI studies in healthy adults given a single 1.2 mg intranasal dose reported connectivity changes in the default mode and amygdala networks. Those are signals, not outcomes, and the two studies appear to share participants.

The route problem

FDA found no published human pharmacokinetic study of Semax by any route. In rats, tritium-labelled intranasal Semax reached the brain within 2 minutes, with the peptide degrading rapidly and Pro-Gly-Pro as the dominant fragment. Brain-to-blood ratios were considerably higher after intranasal dosing than after intravenous.

That matters because the compounding nominations FDA reviewed proposed a 1,000 mcg/mL subcutaneous injection alongside a 7,500 mcg/mL nasal spray, and subcutaneous vials are what most people outside Russia buy. Subcutaneous dosing gives a more systemic and less direct nose-to-brain exposure profile, and it has no human data whatsoever. Route is not a technicality here. It is part of the evidence, and when the route changes, the evidence does not travel with it.

Safety, including what the label warns about

The Russian label lists only mild nasal mucosal irritation with prolonged use, and most published human studies did not systematically report adverse events. FAERS holds one report from May 2025 of eye pain and burning after using 0.1% drops bought online, with hospitalisation and symptoms lasting at least a year.

The contraindications are the more useful part: hypersensitivity, pregnancy and lactation, children under 7, and acute psychiatric states, disorders accompanied by anxiety, and a history of seizures. If you have seen Semax recommended for anxiety, that recommendation contradicts the drug’s own label. The anxiolytic in the same Russian family is Selank, covered in our Semax versus Selank comparison.

Two more concerns are worth knowing. FDA flagged the rodent dopamine potentiation as a possible abuse-liability signal, since striatal dopamine potentiation is shared with drugs of abuse, and raised a bleeding-risk concern based on the antithrombotic findings, which matters for anyone on an anticoagulant or antiplatelet. FDA also judged Semax “not well characterized” for impurities, aggregation, endotoxin and bioburden, which is a product-quality problem rather than a pharmacological one and hits injectable grey-market material hardest.

WADA status is genuinely unsettled. Semax is not named on the 2026 Prohibited List or the 2026 Monitoring Program. Section S0 covers substances with no approval by any governmental health authority, and Semax is registered in Russia, so S0 applicability is legally ambiguous and no ruling was found. A tested athlete should treat it as high risk and get a written determination.

If the complaint is brain fog

“Brain fog” is not a diagnosis, and the common causes in working-age adults are treatable: sleep loss or apnoea, depression or anxiety, medication and alcohol load, iron deficiency, thyroid disease, perimenopause, post-viral fatigue and undiagnosed ADHD. No peptide addresses any of those, and Semax is contraindicated on its own label in one of them. See the Semax molecule profile for the full record.

The bottom line

Semax is a real Russian medicine with a long local track record, a printed label and a coherent rodent mechanism story. It is also supported by small, largely unblinded, developer-authored studies using surrogate endpoints, with no trial registrations, no Western replication, no human pharmacokinetics, and no human data at all for the injectable form most buyers get. Its own label rules it out for anxiety and seizure history. That combination is not a reason to dismiss it, and it is not close to a reason to treat it as established.

Education only. This page is educational. Most compounds referenced are not approved for human use, and a “research use only” label carries no legal status of its own. Nothing here constitutes medical advice, diagnosis, or treatment.

Sources

• Dolotov OV, et al. Semax, an analogue of adrenocorticotropin (4-10), binds specifically and increases levels of brain-derived neurotrophic factor protein in rat basal forebrain. Journal of Neurochemistry, 2006.
• Eremin KO, et al. Semax, an ACTH(4-10) analogue with nootropic properties, activates dopaminergic and serotoninergic brain systems in rodents. Neurochemical Research, 2005.
• Gusev EI, et al. Effectiveness of semax in acute period of hemispheric ischemic stroke (a clinical and electrophysiological study). Zhurnal Nevrologii i Psikhiatrii im S S Korsakova, 1997.
• Gusev EI, et al. The efficacy of semax in the tretament of patients at different stages of ischemic stroke. Zhurnal Nevrologii i Psikhiatrii im S S Korsakova, 2018.
• Shevchenko KV, et al. Kinetics of Semax penetration into the brain and blood of rats after its intranasal administration. Bioorganicheskaia Khimiia, 2006.
• Lebedeva IS, et al. Effects of Semax on the Default Mode Network of the Brain. Bulletin of Experimental Biology and Medicine, 2018.
• Fujimura H, et al. Brain-derived neurotrophic factor is stored in human platelets and released by agonist stimulation. Thrombosis and Haemostasis, 2002.
• Peptogen instructions for medical use, Semax 0.1% and 1% nasal drops. FDA Pharmacy Compounding Advisory Committee briefing document and presentation slides, 23 to 24 July 2026. Health Canada public advisory, unauthorized injectable peptide drugs seized from an online seller, 1 August 2025. WADA 2026 Prohibited List and 2026 Monitoring Program.