Semax / Selank
Semax and Selank blend (Russian nootropic peptide pair)
Written by Aaron CuhaReviewed Sep 2026
Also known as: Semax and Selank stack, Semax/Selank combo spray, The nasal nootropic pair
In plain English, from Aaron
This is how I would explain it to a friend. The evidence, with the numbers, is further down the page.
These are two Russian brain peptides sold as a pair. You spray them up your nose. One is meant to sharpen you up. The other is meant to calm you down. You can buy them as two bottles or as one mixed bottle. Both are approved medicines in Russia. Neither is approved here. Nobody has ever tested them together.
What people take it for
- Focus and clearer thinking at work.
- Taking the edge off anxiety without feeling drugged.
- Handling stress better over a few weeks.
- Some people believe one balances out the other. Nobody has tested that.
What the trials actually showed
There is no study of the two together. Each one on its own has Russian studies, and they are not the kind of study this site calls strong. The sharp one was given to 110 people after a stroke. They got better faster. But nobody was blinded and there was no dummy group. The calm one went to 62 people with anxiety. It worked about as well as a benzo it was compared against. There was no dummy group there either. The rest is rats. Now the mix. In Russia the two are sold at different strengths. The sharp one is 1 mg per mL, so a spray gives about 100 micrograms. The calm one is 1.5 mg per mL, so a spray gives about 150. Mixed bottles sold here usually put 2.5 mg per mL of each in. That is a spray of about 250 micrograms of each, which is more of both and a ratio that matches neither Russian product. Here is the real problem. The whole point of this pair is balance. Balance means moving one and not the other. One bottle takes that away. If the sharp one has you wired, cutting back also cuts the calm one, which was the reason you bought the pair. One more thing worth knowing. A Belgian lab tested two mystery products seized in 2017 and 2018. They turned out to be these two peptides. The lab wrote a detection method because this stuff circulates with no label on it.
What people report
Reports, not trial results
The good
- Sharper focus and words coming easier, 20 to 40 minutes after a spray.
- A flatter, calmer mood people credit to the second peptide. Not sleepy, just less edgy.
- Handling a stressful stretch better after a few weeks of use.
The bad
- Wired, irritable and unable to sleep if the sharp one goes in too late in the day. This is the most common complaint, and it is the reason people add the second one.
- Headache.
- A stinging, runny nose. People blame the volume and the preservative more than the peptides.
- A bitter metal taste at the back of the throat.
- Nothing at all, which people blame on the seller. Given that unlabelled samples have been seized in Europe, that is a fair worry.
- Losing track of which one is doing what. That only happens with the mixed bottle.
Where these come from: None of this is from a trial, because there is no trial of the pair. It comes from nootropic and peptide forums such as r/Nootropics and r/Peptides, and from seller and clinic write ups. The Russian studies on this page did not collect side effects the way a Western trial does.
My bottom line
If you are going to run this pair, buy two bottles, never one. The whole idea is dialling one up and the other down, and a mixed bottle is the one format that will not let you do it.
An opinion, not a finding. I am a coach, not a doctor.
Overview
Two Russian peptides sold as a pair, either as separate nasal sprays or as one combined bottle, on the pitch that one sharpens and the other calms. No study has tested them together. The single products have Russian clinical data, 110 stroke patients for Semax and 62 anxiety patients for Selank, and neither was blinded against placebo. A combined spray at 2.5 mg per mL of each inverts the ratio the two are registered at in Russia.
Semax and Selank are the two peptides that came out of the same Russian institutional programme and ended up in the same medicine cabinet. Semax is a synthetic analogue of ACTH 4-10 registered in Russia and Ukraine for stroke recovery and cognitive disorders. Selank is a synthetic analogue of tuftsin registered in Russia as an anxiolytic. The pitch for the pair is straightforward and intuitive: Semax is the stimulating one, Selank is the calming one, and together you get focus without the edge. That is a plausible story. It has never been tested.
What has been tested is each peptide alone, in Russia, mostly without the blinding and placebo control that the rest of this database's Strong ratings rest on. The main Semax human study followed 110 post-stroke patients, found raised plasma BDNF and faster Barthel index improvement, and was not a blinded placebo-controlled trial. The main Selank human study randomised 62 patients with generalised anxiety disorder or neurasthenia to Selank or the benzodiazepine medazepam, and found the anxiolytic effects similar; that is an active comparator design with no placebo arm. Both peptides have rat work behind their mechanisms, Semax on hippocampal BDNF and trkB and Selank on stress behaviour in the tuftsin family. None of that work involves the other peptide.
The mass split on this blend is the one case in this batch where the arithmetic is almost even. Semax weighs 813.9 Da and Selank weighs 751.9 Da, so an equal-mass mixture is also close to an equal-molecule mixture, with about 8 percent more Selank molecules per milligram. That sounds tidy until you compare it with how the two are actually registered. In Russia Semax is a 0.1 percent nasal solution, 1 mg per mL, delivering about 100 micrograms in a 0.1 mL spray. Selank is a 0.15 percent solution, 1.5 mg per mL, delivering about 150 micrograms per spray. The registered products run at a 1 to 1.5 ratio in Selank's favour. Combined sprays sold to consumers are commonly compounded at 2.5 mg per mL of each, which is 50:50 and delivers about 250 micrograms of each per spray. That is a different ratio from either registered product and a higher per-spray dose of both.
The specific problem a combined spray creates is that it removes the only adjustment that matters for this pair. The whole reason to run Semax with Selank is to balance stimulation against anxiety, and balancing means moving one without the other. In one bottle every dose of the stimulating peptide is also a dose of the calming one at a ratio someone else picked. If the Semax is too much, the only move available lowers the Selank that was supposed to take the edge off. Two bottles cost more and take two sprays, and they are the only version of this stack that can actually be tuned.
There is a supply problem worth stating plainly as well. A 2020 Belgian analysis of two suspicious pharmaceutical preparations seized in 2017 and 2018 found they contained Selank and Semax, and the authors noted that to their knowledge neither peptide had completed any clinical trial. The pair circulates as unidentified powder and unlabelled spray often enough that a national control laboratory built a detection method for it.
Mechanism of action
Semax, an ACTH 4-10 analogue with added residues for stability, raises BDNF and NGF expression and modulates melanocortin and dopaminergic signalling; in rats a single dose raised hippocampal BDNF protein and trkB phosphorylation. Selank, a tuftsin analogue, modulates GABA and monoamine systems and influences enkephalin degradation and BDNF expression, producing anxiolysis without the sedation profile of benzodiazepines. The combination rationale is that the two act on overlapping neurotrophic pathways from opposite directions on arousal. No study has measured what either does to the other.
Human evidence
Each peptide has Russian clinical data of a standard this site rates as Moderate at best, and neither dataset was blinded against placebo. There is no human data on the two given together.
- Semax, 110 post-stroke patients: raised plasma BDNF and faster Barthel index improvement. Not blinded, not placebo-controlled.
- Selank, 62 patients with generalised anxiety disorder or neurasthenia: anxiolytic effect similar to the benzodiazepine medazepam, with additional anti-asthenic and psychostimulant effects reported. Active comparator, no placebo arm.
- Both peptides are registered medicines in Russia, Semax for stroke and cognitive disorders and Selank as an anxiolytic, which is a regulatory fact rather than a trial result.
- A Belgian control laboratory analysing seized preparations in 2020 noted that to its knowledge neither peptide had completed any clinical trial.
What this does not tell you: No study has given Semax and Selank to the same person in a published protocol. Nobody has measured whether Selank blunts the stimulation people take Semax for, whether Semax undercuts the anxiolysis people take Selank for, or whether the combination does anything neither does alone. Nasal absorption has not been characterised for either peptide outside Russia, so per-spray doses are estimates of what enters the bottle rather than measurements of what reaches the brain. Nothing has been published on the stability of the two in one solution.
Reading the research record
The evidence gap here is partly geographic rather than purely commercial. Both peptides went through a Soviet and then Russian regulatory path with clinical standards that Western regulators do not accept, and the resulting literature is real but sits at a lower evidentiary tier than a blinded placebo-controlled trial. That is not the same as saying nothing happened in those studies. It is saying that a Russian registration and a 110-patient unblinded study are not what the word approved means on the rest of this site, and that a combination product built on top of two such records inherits both limitations and adds a third.
The practical problem this blend creates is unusually clean, because the two components are supposed to pull in opposite directions on the same axis. Stimulation and calm is the one pairing where the ratio is the entire product. Fixing it in one bottle at a ratio that matches neither registered Russian product means the user has no way to find their own balance and no way to attribute an effect. If a combined spray makes someone anxious and wired, they cannot tell whether the Semax is too high or the Selank is failing, and the only lever available moves both.
The supply side is worth its own sentence. The Belgian analysis exists because these peptides show up as unidentified material, and the same paper notes they are sold openly online as powder and as sprays. A buyer of a combined spray is trusting a compounder's ratio and a compounder's identity claim, with no registration behind either.
The evidence, charted
Fig. 1 · evidence composition
2of 5 citations (40%) are in people
Counted from the citation list on this page. The Human count is the same number shown in the badge at the top. Both understate any literature larger than the sources we cite.
Fig. 2 · evidence over time
Evidence spans 5 distinct years, 2003 to 2020, counted from the citation list on this page. The newest citation on file is from 2020, more than five years ago; the published record may have gone quiet.
Fig. 3 · legal status at a glance
US
Not approved
UK
Not approved
AU
Not approved
CA
Not approved
Not approved in any of the four jurisdictions shown. A jurisdiction's classification is a regulatory fact, not a verdict on the science; see Legal status below for the full text and any notes.
Fig. 4 · dose response
No human dose response curve exists
We draw this figure where the data supports it. For this compound in humans it does not, so the panel stays empty rather than borrowing an animal curve and implying it transfers.
Key studies & citations
- Animal2006
Semax, an analog of ACTH(4-10) with cognitive effects, regulates BDNF and trkB expression in the rat hippocampus
A single dose of 50 micrograms per kilogram raised hippocampal BDNF protein 1.4-fold, trkB phosphorylation 1.6-fold and BDNF mRNA 3-fold in rats, alongside improved conditioned avoidance learning. Rats, Semax alone, one dose. The mechanistic basis of the Semax half, not evidence about the pair.
Brain Research - Human2018
The efficacy of semax in the treatment of patients at different stages of ischemic stroke
Russian clinical study of 110 post-stroke patients. Semax courses raised plasma BDNF and were associated with faster Barthel index improvement. This was not a blinded placebo-controlled trial, and no Selank was given.
Zhurnal Nevrologii i Psikhiatrii imeni S.S. Korsakova - Human2008
Efficacy and possible mechanisms of action of a new peptide anxiolytic selank in the therapy of generalized anxiety disorders and neurasthenia
62 patients with generalised anxiety disorder or neurasthenia randomised to Selank, 30 patients, or the benzodiazepine medazepam, 32 patients. Anxiolytic effects were similar between the two, and Selank additionally showed anti-asthenic and psychostimulant effects. An active comparator design with no placebo arm, and no Semax given.
Zhurnal Nevrologii i Psikhiatrii imeni S.S. Korsakova - Animal2003
Selank and short peptides of the tuftsin family in the regulation of adaptive behavior in stress
In rats and mice under conflict-induced emotional stress, Selank and related tuftsin-family peptides produced positive emotional and anti-stress effects. Rodents, Selank alone.
Neuroscience and Behavioral Physiology - Review2020
The occurrence of putative cognitive enhancing research peptides in seized pharmaceutical preparations: An incentive for controlling agencies to prepare for future encounters of the kind
Two unknown suspicious preparations seized in Belgium in 2017 and 2018 were analysed and found to contain Selank and Semax. The authors state that to their knowledge neither peptide has completed any clinical trials, and note the pair is freely sold online as lyophilised powder and as nasal sprays. A national control laboratory built an LC-MS/MS method specifically because these were circulating unidentified.
Drug Testing and Analysis
What users report
Self-reported experiences, not evidence. Nothing below was measured under controlled conditions, and reports like these cannot separate a real effect from placebo, from the training or diet change that accompanied it, or from what the product actually contained. They are here because knowing what people describe, including what goes wrong, is worth reading alongside the studies.
- Sharper focus and easier verbal recall within 20 to 40 minutes of a Semax spray, which is the most consistent report on the pair.
- A flatter, calmer mood attributed to the Selank, described as taking the edge off without sedation.
- Better stress tolerance over a course of several weeks rather than acutely.
- Overstimulation, irritability and trouble sleeping when Semax is dosed late in the day, which is the most common complaint and the reason people add Selank in the first place.
- Headache and nasal irritation, stinging or a runny nose, which users attribute to the volume and the preservative rather than to the peptides.
- A metallic or bitter taste at the back of the throat after a spray.
- No effect at all, which is frequent and is usually blamed on vendor quality given that seized samples have been found circulating unlabelled.
- Losing the ability to tell which peptide is doing what, which is specific to the combined bottle and does not happen with two separate sprays.
Sources: None of this is from a trial. There are no exit interviews for the combination because there is no trial of the combination. These reports come from nootropic and peptide user forums including r/Nootropics and r/Peptides, and from vendor and clinic write-ups. The Russian studies cited on this page did not collect side effect data in a form comparable to a Western adverse event table.
Frequently asked questions
Has Semax with Selank ever been studied?
No. Not together, in anyone, anywhere. The Russian clinical studies used one peptide at a time. The idea that one balances the other is a reasonable guess that nobody has tested.
How much of each is in a combined spray?
Combined bottles are commonly compounded at 2.5 mg per mL of each, so a 0.1 mL spray delivers about 250 micrograms of each. That is 50:50 by mass and, because the two molecules weigh almost the same, close to 50:50 by molecule count too. Note that it is not the ratio either drug is registered at in Russia, where Semax runs at 1 mg per mL and Selank at 1.5 mg per mL.
Should I buy the combined spray or two separate ones?
Two separate sprays, if you are going to do this at all. The entire point of the pair is balancing stimulation against calm, and a fixed ratio in one bottle is the one thing that makes balancing impossible. It also means you can never tell which peptide produced an effect.
Is either of these approved anywhere?
Both are registered medicines in Russia, Semax for stroke recovery and cognitive disorders and Selank as an anxiolytic. Neither is approved by the FDA or the EMA. In the US, Semax was removed from FDA Category 2 in April 2026 and an advisory committee voted in July 2026 to recommend it for compounding, but that vote changes nothing until the FDA completes rulemaking.
Is Selank addictive like a benzodiazepine?
The published research does not describe the tolerance and dependence pattern typical of benzodiazepines, and the one randomised study put it head to head with medazepam rather than against placebo. That is a thin basis for a safety claim. Human evidence outside Russia is essentially nonexistent.
How do I know what is actually in the bottle?
You mostly do not. A Belgian national control laboratory analysed two seized preparations and found Semax and Selank in them, and built a detection method precisely because these circulate unidentified. There is no registration, no batch testing requirement and no independent assay behind a combined spray bought online.