Semax + Selank blend: contents and what is known of the combination

In short

Semax + Selank is a peptide blend sold online in vials and as a nasal spray that sellers declare to contain two peptides developed in Russia. The combination has not been studied: in the only study we found that included both substances, they were given to separate groups.

• Three sellers declare the composition in different ways: equal amounts of Semax and Selank, three times as much Selank, or modified N-acetyl amidate forms. The contents have not been tested by an independent laboratory [2]E, not peer-reviewed.
• The substances have been studied separately in small Russian patient studies: Semax after stroke [4]B and Selank for anxiety [6, 7]B.
• According to a Russian review, both are registered peptide medicines in Russia [12]. Neither has a marketing authorisation in the EU [16]regulator.
• In a laboratory test, both inhibited the same enzymes in human blood [8]D. What the two do together has not been studied.
• Selank and the Semax derivative N-acetyl-semax are on annex 1 A of Finland's medicines list [17]regulator. WADA's list names neither, and according to a review their status in sport is unclear [13, 19].

What is the Semax + Selank blend?

The seller declares the composition as Semax and Selank, and the composition has not been independently verified. Sellers' declarations differ from each other, and the contents have not been tested by an independent laboratory [2]E, not peer-reviewed.

Semax + Selank is a blend of two short synthetic peptides in one vial or nasal spray. On the product pages of three sellers (15 Oct 2026), the composition varied [2]E, not peer-reviewed:

• one seller declared equal amounts of Semax and Selank, 5 mg + 5 mg or 10 mg + 10 mg per vial
• another declared 5 mg + 5 mg, or 30 mg Selank and 10 mg Semax per vial, and also sold the pair as a nasal spray
• a third declared the modified forms N-acetyl Semax amidate and N-acetyl Selank amidate, 10 mg of each.

So the name "Semax + Selank" does not tell which forms are in the vial or in what ratio. Sellers are not named or linked.

The parts are:

• Semax: a seven-amino-acid peptide (Met-Glu-His-Phe-Pro-Gly-Pro) derived from the 4-10 segment of the hormone ACTH [8]D [12].
• Selank: a seven-amino-acid peptide (Thr-Lys-Pro-Arg-Pro-Gly-Pro) [8]D derived from tuftsin, a peptide of the immune system [9]C.

Both end in the same three-amino-acid segment Pro-Gly-Pro [8]D. Semax was developed at the Institute of Molecular Genetics of the Russian Academy of Sciences [12]. On blends in general: Peptide blends: what is in the vial and why the seller's declaration is not enough. All blends: Blends. Basics: What are peptides?. All substances: Peptides A-Z.

Evidence at a glance

Each cell gives the kind of study and its source. The letter is the evidence level, not the result. Rows on the single substances do not apply to the blend.

"-" = no study of this.

What is the combination of Semax and Selank studied for?

Nothing: no study in which the substances were given together has been published, and no Semax or Selank trial at all has been registered in the international trial registry (as of 15 Oct 2026). Separately, they have been studied in Russia:

• Semax: treatment and rehabilitation of stroke [4]B. According to a Russian review, Semax is used in Russia to treat stroke [12].
• Selank: generalised anxiety disorder, neurasthenia and other anxiety disorders [6, 7]B. In the Russian review's list it is an anti-anxiety medicine [12].

Online claims. The blend is sold as a combination for memory and attention and for relieving anxiety. According to a Belgian regulatory laboratory, such putative cognitive-enhancing peptides are freely sold online as injectable powder or in nasal sprays, and the authors were not aware of Semax or Selank having completed clinical trials [11]D. Improved memory in healthy people has not been shown for either substance (see Semax and Selank).

How does the Semax + Selank blend work?

This is not known, because their combined effect has not been measured. One known shared feature is that in a laboratory test both Semax and Selank inhibited enzymes in human blood that break down the body's own enkephalins. The researchers suggested this may be one of the ways the substances act [8]D.

Otherwise the substances are thought to act differently. In stroke patients, blood levels of the growth factor BDNF rose in those given Semax [4]B. In anxiety patients given Selank, the half-life of leu-enkephalin in the blood lengthened during treatment [6]B.

In a brain imaging study in healthy volunteers, Semax and Selank had both shared and separate effects on the connections between the amygdala and the temporal lobe. The substances were given to separate groups, not together [3]B.

Has the combination of Semax and Selank been studied in humans?

No. There is no published study in which the substances were given together (as of 15 Oct 2026). The closest is a study in which healthy volunteers received Semax, Selank or placebo [3]B.

The study that included both substances

52 healthy participants received an injection of Semax, Selank or placebo, and functional connections in the brain were measured by MRI before the injection and 5 and 20 minutes after it. Differences between the groups were seen in the connections between the right amygdala and the right temporal lobe [3]B. The study did not measure memory, anxiety or the combination.

What is known about the substances separately

The following results concern the single substances, not the blend. The studies are small, almost all Russian, and their abstracts describe neither randomisation nor blinding.

• Semax after stroke (2018). 110 patients were divided into early and late rehabilitation groups, and in each some received Semax. Blood BDNF rose in those given Semax, and according to the researchers everyday function improved faster [4]B.
• Semax in healthy people (2018). 14 volunteers received Semax in the nose and 10 placebo. The front part of the brain's resting-state network was larger on MRI in the Semax group [5]B.
• Selank for anxiety (2008). 30 patients received Selank and 32 medazepam. According to the researchers the anti-anxiety effect was similar [6]B.
• Selank and phenazepam (2014). In a comparison of 60 anxiety patients, the researchers reported a clear anti-anxiety effect of Selank that lasted a week after the last dose [7]B.

What is known about the single substances does not carry over to the blend. More: Semax and Selank.

Promising, but so far only in animal and cell studies

These findings concern the blend's parts separately, not the blend. They have not been tested in humans, and results from animal or cell studies cannot be transferred directly to people.

• Anxiety in a Parkinson's disease model no human studies

  In rats whose brain dopamine neurons had been damaged to resemble Parkinson's disease, Selank reduced anxiety in a test where the animal chooses between open and sheltered arms. Semax did not affect anxiety, and neither affected movement [9]C.

  If it held in humans: Selank might also relieve anxiety in people with Parkinson's disease.

  Why it might not translate: the result comes from one rat study in which the substances were given separately, and the rats' behavioural test reflects human anxiety only in part [9]C. Selank's anxiety studies in humans had no placebo group [6, 7]B.

  Evidence now: one rat study from 2017 [9]. No human trial of this use has been registered (as of 15 Oct 2026).

• Developing nerve cells no human studies

  In mouse embryonic stem cells, Semax improved cell survival under nutrient deprivation, and neither substance was toxic to the cells. Selank did, however, reduce the share of cells developing into GABA neurons [10]D.

  If it held in humans: Semax might protect developing cells under nutrient deprivation, but Selank could affect what kind of nerve cells develop. The experiment says nothing about safety in pregnancy or fetal development.

  Why it might not translate: the result comes from a mouse cell culture, not a living animal, and there are no human data on use in pregnancy [10]D.

  Evidence now: one cell study from 2017 [10]. The study did not test the substances together.

Who is researching the combination of Semax and Selank?

No one, as far as we know. Almost all research on both substances is Russian, and Semax was developed at the Institute of Molecular Genetics of the Russian Academy of Sciences [12]. The only study that included both substances was done in the same Russian research setting [3]B. From outside Russia, a regulatory laboratory analysis [11]D and reviews [13, 14, 15] have been published. Other guides: Guides.

Author of this page: the editorial team

This page was written by the Molecular Recovery editorial team. The draft was made with the help of AI, and the claims have been checked against the sources (AI policy). The page has not been medically reviewed. How we work: About us.

What are the harms of the Semax + Selank blend?

There is no research data on the harms of the blend, because it has not been studied. According to Fimea, there is no reliable information on the content, quality and safety of products sold as peptides, and their effect on the body can be unpredictable [1]regulator.

What users report. In the Reddit accounts we compiled (not research), 20 of 54 people (37%) reported some harm, most often: anxiety, irritability or overstimulation (7, 13%), insomnia (5, 9%), fatigue or crash (4, 7%) and emotional blunting or low mood (4, 7%). People tend to post when something goes wrong, so this share does not tell how common harms are. The figures are about Semax and Selank used together, as a ready-made blend or at the same time, not about either one on its own, and the products' contents were not verified. 26 people (48%) also used other substances at the same time. The harms in detail: Semax + Selank blend user experiences.

What is known about the safety of the substances

• According to a 2026 review, the absence of serious adverse events in the Russian literature is encouraging but not enough for firm conclusions, because of publication bias and differing safety monitoring practices [14].
• A US review calls Selank a poorly studied Russian drug that is sold in the United States as a dietary supplement [15].
• According to FDA, Semax and Selank may carry a risk of immune reactions by certain routes, and FDA lacks sufficient safety information on them [18]regulator.
• In injectable products, impurities introduced during manufacture, such as endotoxins, raise the risk of serious harm [1]regulator.

The observed harms of the single substances are on their pages: Semax and Selank.

What users report (anecdote, not research)

In the Semax accounts, 31 of 77 writers also used Selank, and in the Selank accounts 22 of 66 writers also used Semax. In both sets the nasal spray was the most common route reported (Semax 23 nasal and 13 injected, Selank 18 nasal and 9 injected). Other substances named alongside included NAD+ (5 writers in the Semax set and 7 in the Selank set) and DSIP (4 in the Semax set). The accounts cannot show which substance had an effect. The accounts: Semax user experiences and Selank user experiences.

More on the harms of peptides: Side effects and safety.

Interactions and who has no data

Interactions with other medicines have not been studied for the blend. Selank has been given together with the benzodiazepine phenazepam (see Selank), but the interaction between Semax and Selank has not been studied. Both inhibited the same enzymes in the laboratory [8]D, but what follows from using them together cannot be inferred from the single studies, and it has not been measured. There are no data on pregnancy, breastfeeding or children.

What speaks against it and what is unknown

There is not a single study of the combination, and the human studies of each substance are small and poorly described [4, 6]B [14].

Counter-evidence

• In rats Semax did not affect anxiety, although Selank did [9]C. So the substances do not have the same effects.
• Researchers at a Belgian regulatory laboratory considered the substances potentially dangerous and were not aware of them having completed clinical trials [11]D.
• Selank's patient studies had no placebo group, and their authors include the same names [6, 7]B.
• According to a review, the safety data in the Russian literature are not enough for firm conclusions [14].

What the evidence does not support

• "Semax and Selank work better together": this has not been studied. In the only study that included both, they were given to separate groups [3]B.
• "The blend improves memory in healthy people": this has not been shown for either substance or for the blend (see Semax and Selank).
• "Approved in Russia means safe": neither has a marketing authorisation in the EU [16]regulator, and a review has noted the gaps in the safety data [14].
• "The vial contains what the label says": sellers' declarations differ even on the form of the substance [2]E, not peer-reviewed, and according to Fimea an unauthorised product may contain a different substance from the one stated on the package [1]regulator.

It is also unknown whether the substances keep as well in the same solution as separately.

Dosage of the Semax + Selank blend in studies

The blend has no approved or studied dosage, because it has not been studied and neither substance has a marketing authorisation in the EU [16]regulator. The milligram amounts declared by sellers describe the vial's content, not a dose [2]E, not peer-reviewed. The blend itself has no dose page of its own.

The doses used in Semax studies are on its dose page: Semax doses in studies. The abstracts of Selank's patient studies do not give doses (see Selank). They do not concern the blend and are not recommendations. Unit conversions for Semax: Semax calculator; there is no calculator for the blend. Doses of other substances: Dosing.

Semax vs Selank: what is the difference?

Semax and Selank are different substances, even though they are sold together. Both are seven-amino-acid peptides ending in the same segment Pro-Gly-Pro [8]D.

• Origin: Semax is derived from a segment of the hormone ACTH [12], Selank from the peptide tuftsin [9]C.
• Human studies: Semax has been studied in stroke [4]B, Selank in anxiety [6, 7]B.
• Animal study: in rats Selank reduced anxiety, Semax did not [9]C.
• Finland's medicines list: Selank is named in annex 1 A, Semax only as the derivative N-acetyl-semax [17]regulator.

Situation in the United States

In the United States, FDA's page lists Semax and selank acetate among the substances that had been nominated as bulk drug substances for compounding and whose nominations were withdrawn by the nominator. According to FDA's risk description, they may carry a risk of immune reactions, and FDA lacks sufficient safety information (updated 22 Apr 2026) [18]regulator. According to a review, Selank is sold in the United States as a dietary supplement [15].

Is the Semax + Selank blend legal in Finland?

The blend has no marketing authorisation, and Selank is on annex 1 A of Finland's medicines list, whose substances are controlled as medicines [16, 17]regulator.

• Medicines list. Annex 1 A of Fimea's decision 230/2025, which covers drug analogues and prohormones classified as medicines, names Selank, N-acetyl-selank and N-acetyl-semax. Semax itself is not named [17]regulator. One seller declares that its blend contains exactly the N-acetyl forms [2]E, not peer-reviewed.
• Marketing authorisation. EMA's medicine data (14 Oct 2026) contain no product with Semax or Selank [16]regulator.
• Fimea's warning of 29 Jun 2026. Fimea warned against injectable peptides bought online. A "for research use only" label means the product is not intended for humans [1]regulator.
• Import. Peptides and the law in Finland. Elsewhere in Europe: Peptides and the law in Europe. On bringing them back from travel: Travelling with peptides.

This is not legal advice. Disclaimer.

Is Semax + Selank doping?

Not known for certain. WADA's 2026 Prohibited List does not name Semax or Selank [19]regulator. Class S0 bans at all times substances with no approval by any health authority for human therapeutic use [19]regulator, but according to a Russian review both are registered in Russia [12].

According to a Polish review, the status of both in sport is unclear. The review's authors consider that Semax could be treated like tetracosactide in class S2 because of its structure or effect [13]. Athletes should ask their own anti-doping organisation.

How can you judge the quality of a Semax + Selank product?

There is no certainty about a product's content without independent analysis. A Belgian regulatory laboratory identified Semax and Selank in two unknown seized preparations and developed its own method to identify them [11]D.

A certificate of analysis (COA) for the blend should identify each substance separately by mass spectrometry (MS), say whether it is the plain or the N-acetyl form, state the amount of each and cover the same batch as the vial. For a nasal spray, the certificate does not show how well the substances keep in solution after opening. More: How to read a COA and check a test result. Handling: Mixing and handling.

FAQ

Read the research yourself: sources

Every source opens the original publication or the regulator's page. The level shows what the source itself reports.

1. Fimea. Fimea warns: do not use injectable peptides purchased online (29 Jun 2026). Fimea regulator
2. Seller product pages for Semax/Selank blends, 3 sellers, read 15 Oct 2026: one declares Semax and Selank 1:1 (5 mg + 5 mg or 10 mg + 10 mg per vial); one declares 5 mg + 5 mg or 30 mg Selank + 10 mg Semax per vial and also sells a nasal spray of the pair; one declares the modified forms N-acetyl Semax amidate and N-acetyl Selank amidate, 10 mg + 10 mg. Sellers' own claims, not tested by an independent laboratory. Not linked: this site does not link to shops. E, not peer-reviewed
3. Panikratova YR, Lebedeva IS, Sokolov OY, et al. Functional Connectomic Approach to Studying Selank and Semax Effects. Dokl Biol Sci. 2020;490(1):9-11. PMID 32342318 B
4. Gusev EI, et al. The efficacy of semax in the treatment of patients at different stages of ischemic stroke. Zh Nevrol Psikhiatr Im S S Korsakova. 2018;118:61-68. (In Russian.) PMID 29798983 B
5. Lebedeva IS, et al. Effects of Semax on the default mode network of the brain. Bull Exp Biol Med. 2018;165:653-656. PMID 30225715 B
6. Zozulia AA, et al. Efficacy and possible mechanisms of action of a new peptide anxiolytic selank in the therapy of generalized anxiety disorders and neurasthenia. Zh Nevrol Psikhiatr Im S S Korsakova. 2008;108:38-48. (In Russian.) PMID 18454096 B
7. Medvedev VE, et al. A comparison of the anxiolytic effect and tolerability of selank and phenazepam in the treatment of anxiety disorders. Zh Nevrol Psikhiatr Im S S Korsakova. 2014;114:17-22. (In Russian.) PMID 25176261 B
8. Kost NV, et al. Semax and selank inhibit the enkephalin-degrading enzymes from human serum. Bioorg Khim. 2001;27:180-183. (In Russian.) PMID 11443939 D
9. Slominsky PA, et al. Peptides semax and selank affect the behavior of rats with 6-OHDA induced PD-like parkinsonism. Dokl Biol Sci. 2017;474:106-109. PMID 28702721 C
10. Kobylyanskii AG, et al. Studying the Toxic Effects of Some Biologically Active Peptides on the Model of Mouse Embryonic Stem Cells. Bull Exp Biol Med. 2017;163:731-736. PMID 29063333 D
11. Vanhee C, et al. 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. Drug Test Anal. 2020;12:371-381. PMID 31667971 D
12. Deigin VI, et al. Development of Peptide Biopharmaceuticals in Russia. Pharmaceutics. 2022;14(4):716. PMID 35456550 (review)
13. Pokrywka A, et al. "Brain doping" substances: prohibited or not in sports? Biol Sport. 2025;42(4):189-201. PMID 41048238 (review)
14. Mavrych V, Shypilova I, Bolgova O. Therapeutic peptides in gerontology: mechanisms and applications for healthy aging. Front Aging. 2026;7:1790247. PMID 42021992 (review)
15. Doyno CR, White CM. Sedative-hypnotic agents that impact gamma-aminobutyric acid receptors: focus on flunitrazepam, gamma-hydroxybutyric acid, phenibut, and selank. J Clin Pharmacol. 2021;61 Suppl 2:S114-S128. PMID 34396551 (review)
16. European Medicines Agency. Medicine data (data set generated 14 Oct 2026): no product with Semax or Selank. EMA regulator
17. Finland. Lääkeluettelo (Fimea medicines list), 230/2025, annex 1 A: "Selank", "N-asetyyli-selank" and "N-asetyyli-semax"; Semax itself is not named. Finlex regulator
18. U.S. Food and Drug Administration. Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks: "Selank acetate (TP-7)" and "Semax (heptapeptide)" under "Bulk drug substances nominated but withdrawn" (content current as of 22 Apr 2026, read 15 Oct 2026). FDA regulator
19. World Anti-Doping Agency. 2026 Prohibited List, S0 Non-approved substances and S2 (read 15 Oct 2026 in the Finnish Center for Integrity in Sports SUEK's published 2026 list): Semax and Selank are not named. SUEK regulator

Research, registry and regulator sources and seller product pages read on 15 Oct 2026. The 2026 WADA list read as published by SUEK. Sellers are not named or linked.

Evidence levels: A = randomised human trial or meta-analysis · B = observational human study or case series · C = animal study · D = cell or laboratory study · E = not peer-reviewed · regulator = a regulator's assessment or decision, not research evidence. The marker official means official product information (summary of product characteristics or label); it is not research evidence. For a review, the level shows what kind of research the statement rests on. No level: statements that something has not been studied, reviews' interpretations, named hypotheses and the general rules in our certificate-of-analysis guide.

Content is general information about research, not medical advice. If you have symptoms, contact a healthcare professional.