What are Semax and Selank?

Both are short synthetic peptides developed in Russia. Semax derives from a fragment of ACTH and is used there in neurology; Selank derives from tuftsin and was developed as an anxiolytic. Outside Russia they are sold as research chemicals and marketed as nootropics.

Is the research on Semax and Selank real?

Yes, and it is narrower than either its promoters or its critics suggest. There are real clinical studies, published in real journals, from a genuine research programme. They are also overwhelmingly Russian-language, largely from one tradition, mostly two decades old, and not independently replicated in the literature most readers can access.

Do Semax and Selank work for focus, memory or anxiety?

That is what they are studied and used for in their home tradition. What is missing is the independent replication that would let anyone outside it check the result. We would rather tell you the evidence exists and is hard to verify than pretend it is either conclusive or absent.

Are Semax and Selank legal?

They are not approved for human use in the US, and are sold through research-chemical channels where nobody verifies what is in the vial. In Russia they have been used clinically, which is why you will see confident claims that they are approved medicines - true there, not here.

What dose do the studies use?

The clinical work is largely in Russian-language journals that are difficult to obtain and appraise, and we are not going to transcribe dosing out of papers we cannot fully read. That limitation is itself the most useful thing we can tell you about dosing these two.

Research peptides

Semax and Selank: Where That Russian Research Actually Sits

Both rest on a real but narrow literature: mostly Russian-language, mostly two decades old, never independently replicated. We counted it rather than repeating it.

Written bySebastian Hunter, Founder and Editor

Published August 23, 2026

Start here

Plain English

Semax and Selank are peptides developed in Russia and used there clinically, sold elsewhere as nootropics. Their human evidence is real but narrow: mostly Russian-language journals, mostly two decades old, and not replicated in the wider literature. That is a specific limitation, not a dismissal.

Of 231 Semax records on PubMed, 105 are Russian-language. For Selank it is 33 of 135.
The controlled trials are old and have not been independently replicated.
Neither is approved for human use outside that tradition, and both sell as research chemicals.

Everyone who writes about Semax and Selank says the same sentence: “the research is mostly older Russian studies.” It gets repeated as either a dismissal or a wink, depending on who is selling what, and almost nobody checks it.

We checked it. It is true, and the specifics are more useful than the sentence.

What they are

Both are short synthetic peptides developed in Russia and used clinically there. Semax derives from a fragment of ACTH and is used in neurology. Selank derives from tuftsin and was developed as an anxiolytic. Elsewhere they are sold as research chemicals and marketed as nootropics.

What the literature actually looks like

Semax on PubMed, by language of publication

Russian-language recordsof 231 total
105
Tagged as a clinical trialacross the whole corpus
4
Tagged as a randomised trialRussian-language, 2007
1

Counted on PubMed in August 2026. Almost half the Semax literature is Russian-language, and the concentration is heavier still among the clinical studies rather than the laboratory work.

Selank is the same shape at a smaller scale: 135 records, 33 of them Russian-language, six tagged as clinical trials and three as randomised.

And those three do not survive inspection intact. One is a muscular strength and hypertrophy paper that appears to be a false positive of the search rather than a Selank trial at all. The other two are Russian-language papers in the Korsakov journal of neurology and psychiatry, from 2015 Medvedev 2015 - Medvedev VE, Tereshchenko ON, Kost NV et al. [Optimization of the treatment of anxiety disorders with selank]. Zh Nevrol Psikhiatr Im S S Korsakova. 2015;115(6):33-40. (opens PubMed in a new tab) and 2008 Zozulia 2008 - Zozulia AA, Neznamov GG, Siuniakov TS 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(4):38-48. (opens PubMed in a new tab). Semax’s single randomised record is in the same journal, from 2007, and concerns chronic partial denervation Serdiuk 2007 - Serdiuk AV, Levitskiĭ GN, Miasoedov NF et al. [The study of chronic partial denervation and quality of life in patients with motor neuron disease treated with semax]. Zh Nevrol Psikhiatr Im S S Korsakova. 2007;107(4):29-39. (opens PubMed in a new tab).

What that means, said carefully

This is the part where most pages pick a side, so we will be explicit about not doing that.

It does not mean the studies are worthless. Non-English research is research, and waving away a national research tradition because it published in its own language is its own kind of bias. These compounds were developed in a serious programme and used in clinical practice.

It does mean three specific things, and each of them matters to you:

The work has not been independently replicated in the literature most readers, clinicians and regulators can access and appraise.
The clinical trials are roughly two decades old.
You cannot easily check them yourself, and neither can we — which is why you will not find us summarising their results as though we had.

Modern English-language work on these peptides does exist, but it is mechanistic rather than clinical — for instance on how synthetic ACTH-derived peptides alter gene expression patterns Filippenkov 2023 - Filippenkov IB, Remizova JA, Stavchansky VV et al. Synthetic Adrenocorticotropic Peptides Modulate the Expression Pattern of Immune Genes in Rat Brain following the Early Post-Stroke Period. Genes (Basel). 2023;14(7). (opens PubMed in a new tab). Interesting, and not an answer to whether they help you concentrate.

Dose

We are not transcribing dosing out of papers we cannot fully read.

That is not evasion, it is the same standard we apply everywhere: we report doses where a study establishes one and we can verify what the study did. Here the clinical work sits in journals that are difficult to obtain and appraise, and passing along numbers filtered through vendor translations would give them a provenance they do not have.

Status

US legal status - Research use only · not for human use

Sold for laboratory research use only. Not approved by the FDA for human use, and cannot be lawfully marketed as a supplement or a medicine. Products sold this way are not made to pharmaceutical quality standards, and their contents are not verified by anyone.

Neither peptide is approved for human use in the US, and both are sold through research-chemical channels where the contents of the vial are not verified by anyone. You will encounter confident claims that they are “approved medicines” — that is true in Russia and not where you are buying them, and vendors rarely make the distinction.

References

Bibliographic detail is fetched from PubMed, not written by us - so a citation here cannot drift from the paper it names. Study design comes from PubMed's own tags rather than our judgement.