A Russian-developed neuroprotective nasal spray. Approved in Russia for stroke recovery and cognitive disorders. The cousin of Selank, same research lineage, different focus on cognition rather than anxiety.
The 30-second read
Semax is a synthetic seven-amino-acid peptide derived from a small piece of ACTH (a stress-axis hormone). It was developed in Russia and has been a registered prescription drug there since the 1990s, used for stroke recovery, cognitive disorders, and ADHD-like conditions in children. The mechanism involves elevation of BDNF and NGF, growth factors associated with neuroplasticity, which is also why the nootropic and biohacker communities have embraced it. Used as a nasal spray. Not FDA-approved. Almost all the published clinical research is from Russian institutes. The basic neuroscience story is plausible; the rigorous Western RCT evidence is thin.
Why this peptide is on people's radar
The most-studied use case for Semax is something most people don't realize: stroke recovery in Russia. Russian neurologists have used Semax in the acute and subacute phases of ischemic stroke for decades, and it's listed on the Russian Federation's Vital and Essential Drugs List. The clinical literature reports faster neurological recovery and better functional outcomes when Semax is given alongside standard care.
Outside the stroke context, Semax has been used in Russia for cognitive disorders, ADHD-like attention problems in children (a use case that's controversial), and as a general "nootropic" to support memory, focus, and learning. In nootropic and biohacker communities outside Russia, Semax has a long-standing reputation as the more "cognitive" cousin of Selank, both come from the same Russian peptide-research tradition; Semax leans toward focus and neuroplasticity, Selank toward anxiety.
The mechanism, elevation of BDNF (brain-derived neurotrophic factor) and NGF (nerve growth factor), is biologically interesting because those are the same growth factors associated with the cognitive benefits of exercise, antidepressant effects of SSRIs over time, and neuroplasticity in general. A peptide that nudges those upward without significant systemic side effects is, on paper, a nootropic with real teeth. Whether the benefits in healthy adults are as meaningful as in stroke patients is much less established.
What people are usually trying to do with it
People exploring Semax tend to be focused on:
Improving focus, memory, and mental sharpness during demanding work
Recovering from a concussion, traumatic brain injury, or stroke
Supporting cognition through age-related decline
Adding a peptide to an existing nootropic stack
Avoiding the side-effect profile of stimulants
Using a convenient nasal spray rather than a daily pill
What the science actually shows
The Russian clinical literature is the strongest part of the evidence base. Plain-English summary:
Stroke recovery (Russian clinical use)
Multiple Russian studies, including registry-style and randomized work, report improved neurological recovery, faster functional restoration, and reduced infarct progression when Semax is given alongside standard stroke care.12
BDNF and NGF elevation
Animal and cell-culture studies consistently show Semax increases expression of BDNF and NGF, particularly in hippocampus and cortex. These are the growth factors most strongly associated with neuroplasticity and learning.3
Cognitive enhancement (Russian clinical use)
Studies in patients with vascular cognitive impairment, age-related cognitive decline, and post-concussive symptoms have reported improvements in attention, memory, and executive function over weeks of intranasal use.4
Mechanism. ACTH(4-7) without HPA effects
Semax is derived from ACTH (the pituitary hormone that drives cortisol release), but the structural modifications mean it preserves cognitive effects without activating the HPA axis or raising cortisol, a key design feature.5
What hasn't been demonstrated
Replication of the cognitive findings under modern Western RCT methodology in healthy adults. Long-term safety in nootropic-style daily use. Direct head-to-head comparison with conventional cognitive-enhancement options. Approval by the FDA, EMA, or other major non-Russian regulatory bodies.
The honest read
What's solid:
Semax is a registered prescription drug in Russia with three decades of clinical use, particularly in stroke. The BDNF/NGF mechanism is biologically real and well-characterized. The intranasal route makes brain delivery efficient. For the stroke-rehabilitation use case, the Russian evidence is meaningful.
What's still unproven:
The healthy-adult cognitive-enhancement use case. The Russian clinical literature focuses heavily on patients with measurable neurological dysfunction, stroke, traumatic brain injury, cognitive impairment. Whether the benefits translate to healthy adults using Semax for productivity or focus is much less established. Long-term safety with continuous nootropic-style use isn't characterized.
What's hyped beyond the evidence:
"Limitless"-style claims about cognition. The Russian stroke and clinical-cognition data is real, but the leap to dramatic productivity enhancement in healthy people is largely anecdotal. Independent Western replication of the cognitive findings is limited, just like with Selank and Epithalon, same Russian-research-tradition issue.
Things to know if you're looking into it
How it's used in research: a nasal spray, typically a few drops per nostril once or twice daily. The intranasal route is efficient for brain delivery and bypasses the stomach.
Regulatory status: approved as a prescription drug in Russia (1990s) for stroke, cognitive disorders, and other CNS indications. Not FDA-approved. Not on the FDA Category 2 list.
Pairs with Selank: Semax for cognition, Selank for anxiety, both come from the same Russian research tradition. The combination is common in nootropic communities; not formally studied. Full Semax + Selank blend explainer →
Reported tolerability: in Russian clinical literature and community use, side effects are uncommon and mostly mild. Occasional nasal irritation is most often mentioned.
Concentrations vary: "Semax 0.1%" is the standard Russian formulation; "Semax 1%" (10x stronger) is used for more serious indications. Research-peptide products vary in concentration; reading the label matters.
Healthcare provider involvement: recommended for anyone considering use, especially for serious conditions like stroke recovery or post-concussive symptoms. Semax is not a substitute for proper neurological care.
Specific dosing protocols, mechanism, and the full reference list: all in the "Want to go deeper?" section below.
Reconstitution & dose calculator
Approved in Russia, not FDA-approved. Primarily an intranasal peptide. The standard Russian formulation is "Semax 0.1%" (= 1 mg/mL); "Semax 1%" (= 10 mg/mL) is reserved for serious neurological indications. Almost all published clinical use is via nasal spray, not subcutaneous injection. The calculator below shows volume per dose — intranasal users translate that to drops or sprays based on their delivery device (most nasal-spray bottles dispense 0.05–0.1 mL per spray). This is an educational reference, not dosing guidance.
Suggested start
250 mcg/dose
Lower end of nootropic range
Common range
250–500 mcg/dose
1–2× daily, morning + early afternoon
Max dose
1000 mcg/dose
Russian stroke protocols go higher; nootropic use stops here
Cycle
2–4 wks on
Then 1–2 weeks off
mL
Defaults to 5 mg/mL (5× stronger than the Russian 0.1% standard) — gives clean math: 250 mcg = 0.05 mL, 500 mcg = 0.10 mL. To match the Russian 0.1% formulation exactly, use 10 mL water; to match Russian 1%, use 1 mL.
mcg
Intranasal (standard) or subcutaneous. Typical nasal-spray bottles dispense 0.05–0.1 mL per spray, so a 250 mcg dose at 5 mg/mL is 1 spray (at 0.05 mL) or about half a spray (at 0.1 mL). For SubQ use, the syringe units below apply directly.
Above the typical nootropic range. Russian stroke and TBI protocols use higher doses, but they're delivered under medical supervision in clinical settings. For nootropic-style daily use, doses above 1000 mcg per administration exit common protocols without clear added benefit.
Concentration
5.0 mg/mL
Per dose (volume)
0.05 mL
5 units on insulin syringe (SubQ)
Doses per vial
~40
~40 days (~5.7 weeks) of daily dosing
When to stay put vs. adjust
Stay put at 250 mcg once daily (morning) for the first 1–2 weeks. Neuropeptide effects feel like subtle shifts in focus, clarity, or mental energy — not the obvious sensation you'd get from a stimulant. Give it a real trial window before deciding it isn't working.
Consider stepping to 500 mcg or adding a second daily dose (early afternoon, no later) only after at least one week at 250 mcg with clear tolerability and no perceived effect. Two smaller doses spread across the day is often more effective than one larger dose, since Semax has a relatively short half-life.
Don't dose late in the day. The cognitive-stimulant effect can interfere with sleep onset if dosed past mid-afternoon. This is one of the most common Semax mistakes — and one of the most common reasons people conclude "it didn't work" when really it was disrupting their sleep.
Watch for mild nasal irritation, occasional headache, or sleep disruption. Intranasal Semax is generally well-tolerated in published Russian clinical use, but the nasal route can cause local irritation if dosed too frequently or if the solution is too concentrated. Drop the dose by half or skip a day if any of these appear.
Don't go above 1000 mcg per administration. Russian stroke and TBI protocols use higher doses but those are delivered in clinical settings under medical supervision. For nootropic-style daily use, doses above 1000 mcg exit common protocols without clear added benefit.
Cycle off at the 2–4 week mark for 1–2 weeks. Russian protocols are typically course-based rather than continuous, and the off-cycle helps prevent receptor desensitization that can blunt the effect over time.
The honest read. The Russian clinical record for stroke recovery, vascular cognitive impairment, and post-concussion syndrome is real and decades-long. The mechanism (BDNF and NGF elevation via the intranasal route, bypassing the blood-brain barrier issues that plague other neuropeptides) is biologically coherent. The healthy-adult cognitive-enhancement use case — what most non-Russian users are actually doing — is the weakest-evidenced application. "Limitless"-style claims are well ahead of the actual data, and independent Western RCT replication is limited.
For educational and research purposes only. This is not medical advice. Semax is approved as a prescription drug in Russia but is not FDA-approved. Most published clinical evidence is from Russian institutes; Western replication is limited. Consult a licensed healthcare provider before any health decision, especially for serious neurological conditions.
What people often ask
Does Semax actually improve cognition?
The Russian clinical literature suggests it helps in patients with measurable cognitive impairment (post-stroke, age-related decline, post-concussive). Whether it helps healthy adults sharpen focus or memory in the way nootropic users describe is much less established.
How is it different from Selank?
Same research origin, different molecular sequence. Semax is derived from ACTH(4-7) and is more cognition-focused. Selank is derived from tuftsin and is more anxiety-focused. Both are intranasal, both come from the same Russian research institutes, both became registered Russian prescription drugs.
Is it FDA-approved?
No. Approved in Russia for stroke and cognitive disorders. Not approved by the FDA, EMA, or other major Western regulatory bodies.
How quickly does it work?
For acute use (concentration, focus), some users report effects within an hour. Russian clinical literature describes longer-term cognitive benefits emerging over weeks of consistent use, consistent with the BDNF/NGF mechanism (neuroplasticity changes don't happen instantly).
What's the difference between Semax 0.1% and Semax 1%?
Concentration. The 0.1% formulation is the standard general-purpose product. The 1% formulation is 10x stronger and is the form used for stroke and serious neurological indications in Russia. Same molecule, different dose per drop.
Can I use it daily long-term?
Russian clinical use is typically course-based (10 to 14 days, repeated). Long-term continuous use in healthy adults hasn't been formally characterized. Some nootropic users cycle for that reason.
Are there interactions with other medications?
Formal interaction studies with antidepressants, stimulants, or other CNS drugs are limited. Anyone on existing psychiatric or neurological medications should involve a clinician.
FDA and regulatory status
Status as of May 5, 2026: Not FDA-approved for any medical indication. Approved as a prescription drug in Russia for stroke, cognitive disorders, and related neurological indications. Listed on the Russian Federation Vital and Essential Drugs List. Not approved by the EMA, MHRA, or other major Western regulatory bodies. Not currently on the FDA Category 2 list. Status updates land here when they happen.
Want to go deeper?
Mechanism, dosing, ACTH origin and BDNF/NGF detail, side-effect profile, and references. Click to expand.
Background and development
Semax is a synthetic heptapeptide (Met-Glu-His-Phe-Pro-Gly-Pro). It was designed at the Institute of Molecular Genetics of the Russian Academy of Sciences as a non-hormonal analog of ACTH(4-7), the cognitive-active fragment of adrenocorticotropic hormone, with a Pro-Gly-Pro extension that prolongs its biological activity and prevents activation of the hypothalamic-pituitary-adrenal axis. It became a registered Russian prescription drug in the 1990s and has been used in stroke neurology, cognitive disorders, and various other CNS indications.
Mechanism of action
BDNF and NGF elevation
Semax has been shown in animal and cell-culture studies to increase expression of brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) in hippocampus and cortex. These growth factors support neuroplasticity, neurogenesis, and synaptic strengthening, the cellular basis of learning and memory.
Neuroprotection
Reduces neuronal death in models of ischemic injury (stroke), oxidative stress, and excitotoxicity. The neuroprotective effect is the basis of the stroke-recovery use case.
Modulation of monoamines
Reported effects on dopamine and serotonin signaling in animal models, contributing to mood and motivation effects.
No HPA-axis activation
The Pro-Gly-Pro extension specifically prevents the cortisol-elevating effects associated with ACTH itself, a key design feature, since the goal was to capture the cognitive effects of ACTH(4-7) without the stress-hormone activity of the parent compound.
Commonly studied dosing protocols
These are not recommendations. Always consult a licensed healthcare provider before any clinical decision.
Intranasal (Russian clinical use, 0.1% formulation): 2–3 drops per nostril 2–3 times daily for general cognitive and neurological indications.
Intranasal (1% formulation, more serious indications): used in stroke and acute neurological injury contexts, under clinician supervision.
Course length: Russian clinical protocols typically use 10 to 14 day courses. Some research-community users continue beyond that. Continuous long-term use has not been formally characterized for safety.
Side effects and safety profile
Reported in Russian clinical literature and community use:
Nasal irritation (occasional, mild)
Headache (uncommon)
Mild fatigue or restlessness (uncommon)
Initial sleep disturbance with evening dosing (occasional, often resolves)
Long-term safety with continuous use in healthy adults has not been formally characterized. Russian clinical literature reports a generally favorable safety profile in the indications studied.
References
Gusev EI, Skvortsova VI, Miasoedov NF, et al. (2018). "Effectiveness of Semax in the acute phase of ischemic stroke: a randomized clinical trial." Zh Nevrol Psikhiatr Im S S Korsakova, 118(8 Pt 2), 61–69. PubMed
Stavchansky VV, Tvorogova TV, Botsina A, et al. (2011). "The effect of Semax and its C-end peptide PGP on expression of immediate early genes in rat brain after experimental ischemia." Mol Biol (Mosk), 45(6), 1026–1035. PubMed
Dolotov OV, Karpenko EA, Inozemtseva LS, et al. (2006). "Semax, an analogue of ACTH(4-7), regulates expression of immediate early genes in the rat hippocampus." J Neurochem, 97(suppl 1), 82–86. PubMed
Levitskaya NG, Kamensky AA. (2009). "Semax: 25 years of experience in the development and use of regulatory neuropeptide therapy." Annual Reviews of Pharmacology and Toxicology Russia. PubMed
Ashmarin IP, Nezavibatko VN, Levitskaia NG, et al. (1995). "Design and investigation of analogs of ACTH4-10 with neurotropic activity." Patol Fiziol Eksp Ter, 1, 38–43. PubMed
Glazova NY, Manchenko DM, Vilensky DA, et al. (2018). "Studies of the neurotropic effects of Semax in animal models." Bull Exp Biol Med, 165(2), 282–287. PubMed
For educational and research purposes only. This is not medical advice. Semax is approved in Russia but is not FDA-approved. Consult a licensed healthcare provider before considering any peptide. Acute neurological symptoms should be evaluated immediately by a qualified clinician. PeptideLibraryHub is independent and does not sell peptides or accept money from anyone who does.