Selank vs Semax: same Russian lab, different jobs, and only one made the HHS list

The short answer: Selank was built as an anti-anxiety peptide and Semax as a brain-protection and cognition peptide. Both came out of the same Russian institute, both are registered in Russia as nasal drops, and neither is FDA-approved.

The news most comparison pages missed: on October 30, HHS published an interim compounding policy that covers Semax, nasal only. Selank isn't on it, and it isn't on FDA's review lists either.

Status as of November 6, 2026: Neither peptide is FDA-approved. Semax is one of six peptides under the HHS interim enforcement policy, which is not an approval and doesn't add it to the 503A bulks list. Selank is not covered. The human evidence for both is small and almost entirely Russian. Nothing here is medical advice or a dosing guide.

Key takeaways

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They're cousins, not twins. Each is a seven-amino-acid peptide ending in Pro-Gly-Pro (Kost et al., 2001), a tail thought to slow breakdown (FDA briefing, 2026).

Semax is an analog of a fragment of ACTH, the stress-axis hormone. FDA's reviewers describe it as "devoid of the hormonal corticotropic and melanotropic properties" of the full protein. FDA's briefing traces trial supply to the Institute of Molecular Genetics in Moscow.

Selank is an analog of tuftsin, a natural immune peptide. It came from the same institute, working with Moscow's Zakusov pharmacology institute (Volkova et al., 2016).

Sources: Russian listings (Selank, Semax), DLA Piper, HHS policy, Oct 2026.

Semax now has a narrow federal pass. Selank doesn't. Neither is an approved drug: a search of FDA's approved-drug data returns nothing for either name.

HHS says it "does not intend to take enforcement action" against state-licensed pharmacies, federal facilities or licensed physicians compounding a listed peptide (Federal Register, Oct 30, 2026). The HHS policy's Appendix A lists the six as BPC-157, Epitalon, KPV, MOTS-c, Semax and TB-500, and Appendix B limits Semax to the free base, for "intranasal use" (HHS policy, Oct 2026). The full rundown is in the HHS peptide pass.

Three limits matter:

The comment period closes November 13 (Regulations.gov docket).

Why Semax and not Selank? The paper trail shows how, not why. Both nominations were withdrawn. FDA then evaluated Semax "at its discretion." I found no such review of Selank. It wasn't on the July agenda, and it appears in no category of FDA's 503A list (version updated May 14, 2026). BHN's compounding tracker has no Selank row for the same reason. FDA's only stated position: it "lacks important information regarding any safety issues raised by selank acetate administered to humans" (FDA, current as of Apr 22, 2026).

That doesn't make Selank worse. It means no US agency has published a full look at it, and "research use only" labels don't fill that gap.

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Selank, and it isn't close. That doesn't make the evidence good.

Selank has three published anxiety trials, all Russian-language, from overlapping research groups. Semax has none that I could find, only "anxiolytic-like" effects in rodents. Its Russian listings name anxiety disorders as a contraindication (Vidal). So the US sites FDA found marketing Semax for anxiety are selling it for something its home-country listing warns against.

"As good as a benzodiazepine" comes from the 2008 trial below. Thirty people per arm can't prove two drugs are equal, and without a placebo arm, nobody can tell how much improvement came from either drug.

Almost none. I found no ADHD trial of either peptide in PubMed.

Fewer than the marketing implies, and most are small. Nearly all are Russian-language, and for most I had the abstract only, so silence on blinding means the abstract doesn't say.

That last row is the only direct comparison I found. It measured brain connectivity within minutes, not anxiety or focus as a treatment outcome.

One caveat on FDA's verdict. Its reviewers concluded "insufficient evidence," but they skipped the Russian stroke papers: "Because the full references were not available in English, these references were not considered as part of this evaluation." So FDA never graded those trials. It didn't reject them. FDA also noted the clinical papers don't say whether they used the free base or a salt, which matters now that the policy names one form.

Mostly unknown. FDA's own phrase for Semax is "poorly understood mechanisms of action." Nearly every mechanism you'll read comes from animals or cells.

Every paper behind this table is linked in Sources below.

Safety data is just as thin. Selank's Russian listing mentions unpleasant taste and possible allergy. Semax's mentions mild nasal irritation. For Semax, FDA found most papers "did not discuss safety" and flagged possible bleeding risk, mouse data on amphetamine-driven dopamine release, and immune reactions to impurities. Hall Render reports HHS called the Semax concerns "mechanistic rather than based on observed harm" (Hall Render, Nov 4, 2026). No harm seen isn't safety shown when most papers never looked.

Nobody has measured how well it works in people. On Semax, FDA said: "We were not able to find pharmacokinetic studies in humans." I found none for Selank either.

The nose-to-brain idea comes from rats. Radiolabeled Semax reached the brain at about 0.072% of the dose by nose vs about 0.005% by IV. That's better, and still tiny, and it's rat data.

FDA rulemaking decides whether Semax joins the bulks list, and the pass lasts until then unless HHS pulls it. The FDA panel vote post covers what's still required. For Selank, nothing is scheduled that I could find.

If a placebo-controlled Selank trial, human pharmacokinetic data or a proposed FDA rule on Semax lands, I'll update this post.

If you've used either one, reply and tell me what you noticed.

HHS says it won't take enforcement action against state-licensed pharmacies compounding Semax free base for nasal use, under its conditions. That's discretion, not approval, and state rules still apply.

The claim comes from small Russian trials against medazepam and phenazepam, with no placebo. Lab work suggests it may influence GABA signaling, but that hasn't been shown in people.

Nobody knows. I found no trial comparing them for focus, and no clinical trial of either in people with attention problems. The one head-to-head study measured brain scans in 52 healthy volunteers.

I found no clinical trial of the combination. Blends are sold, but the HHS policy requires a single active ingredient, and Selank isn't covered.

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