Are Semax and Selank the same thing?

No. They are two different peptides from the same Russian research lab that share a heptapeptide design and a stabilizing Pro-Gly-Pro tail, but they are derived from different parent molecules. Semax is based on a fragment of the ACTH hormone and targets cognition and neuroprotection, while Selank is based on the immune peptide tuftsin and targets anxiety. They are cousins in design, not the same molecule.

Which one is for focus and which is for anxiety?

Semax is the cognition-oriented peptide, associated with attention, memory, and neuroprotection through a rise in BDNF and TrkB signaling. Selank is the anxiety-oriented peptide, associated with a calming effect through GABAergic and enkephalin systems, reported to work without the sedation of a benzodiazepine. If a source treats them as interchangeable nootropics, it is glossing over that they were built for different jobs.

Can you take Semax and Selank together?

They are sometimes combined in practice because they address different symptoms, cognition versus anxiety, rather than the same one. We do not report doses or endorse stacking, because the human evidence for each peptide individually is small and largely Russian-language, and there are essentially no controlled studies of the two used together to speak to safety or benefit of the combination.

Is either Semax or Selank FDA-approved?

No. Both are registered medicines in Russia but neither is approved by the FDA for any indication. Outside Russia they are sold only as research-use-only chemicals, which means they sit outside the pharmacy channel and carry none of the identity, purity, and sterility assurances of an approved drug, and the online products are not the registered Russian formulations.

What does the human evidence actually show?

For Semax, small mostly Russian-language studies, including a placebo-controlled study in acute ischemic stroke, support a cognitive and neuroprotective role. For Selank, a study in generalized anxiety disorder suggested an anxiolytic effect comparable to a benzodiazepine comparator. In both cases the trials are small and have not been reproduced in the large multicenter format Western regulators require, so the signals are promising rather than proven.

Comparison· Compounds

Semax versus Selank, what actually separates the two peptides

Semax vs Selank on the evidence: two Russian heptapeptides from the same lab, one built for cognition and one for anxiety, what the mechanisms and the trials actually show, and their regulatory status.

By The PepVise Editorial Team · Reviewed July 31, 2026 · 10 min read

Side-by-side comparisons on PepVise rank by weight of evidence, not by bodybuilding forum consensus. Tier badges on every entry.

Methodology

How we read the literature

Evidence tier: We grade the literature on four tiers, High (replicated RCTs or meta-analyses), Moderate (multiple trials with mixed findings), Low (a single pilot or case series), and Anecdotal (preclinical only, no human data). The tier appears on every compound profile beside the claim it supports.
Trial stage: Where a compound sits in the human development pipeline is recorded as Preclinical, Phase 1, Phase 2, or Phase 3+. We pull the current stage from ClinicalTrials.gov and the EU Clinical Trials Register on access date and re-verify quarterly.
Regulatory status: We state the FDA posture plainly, approved for indication X, or labeled for research use only, or removed from the 503A list, or investigational under a specific IND. Regulatory status changes; every post carries a review date.
Where we're uncertain: Every compound profile closes with a named uncertainty section, the question we can't answer from the current literature, the trial we'd want to see, the effect size we'd treat as a real signal. Uncertainty is not a failure mode here; it's load-bearing.

Frequently asked

What readers ask us next.

Are Semax and Selank the same thing?: No. They are two different peptides from the same Russian research lab that share a heptapeptide design and a stabilizing Pro-Gly-Pro tail, but they are derived from different parent molecules. Semax is based on a fragment of the ACTH hormone and targets cognition and neuroprotection, while Selank is based on the immune peptide tuftsin and targets anxiety. They are cousins in design, not the same molecule.
Which one is for focus and which is for anxiety?: Semax is the cognition-oriented peptide, associated with attention, memory, and neuroprotection through a rise in BDNF and TrkB signaling. Selank is the anxiety-oriented peptide, associated with a calming effect through GABAergic and enkephalin systems, reported to work without the sedation of a benzodiazepine. If a source treats them as interchangeable nootropics, it is glossing over that they were built for different jobs.
Can you take Semax and Selank together?: They are sometimes combined in practice because they address different symptoms, cognition versus anxiety, rather than the same one. We do not report doses or endorse stacking, because the human evidence for each peptide individually is small and largely Russian-language, and there are essentially no controlled studies of the two used together to speak to safety or benefit of the combination.
Is either Semax or Selank FDA-approved?: No. Both are registered medicines in Russia but neither is approved by the FDA for any indication. Outside Russia they are sold only as research-use-only chemicals, which means they sit outside the pharmacy channel and carry none of the identity, purity, and sterility assurances of an approved drug, and the online products are not the registered Russian formulations.
What does the human evidence actually show?: For Semax, small mostly Russian-language studies, including a placebo-controlled study in acute ischemic stroke, support a cognitive and neuroprotective role. For Selank, a study in generalized anxiety disorder suggested an anxiolytic effect comparable to a benzodiazepine comparator. In both cases the trials are small and have not been reproduced in the large multicenter format Western regulators require, so the signals are promising rather than proven.

What would change our reading

A new Phase 2 trial for any of the ranked compounds. A regulatory action changing FDA status. A published replication failure in an independent lab. Any of those would move entries on this list within a week, with a dated note on what changed.

The sources

References cited on this page.

PubMed, ClinicalTrials.gov, and FDA documents only. Secondary sources appear when needed to characterize public discourse, never as a source for a clinical claim.

The masthead

About The Pepvise Editorial Team

The Pepvise Editorial Team is a small group of researchers and science writers reading the peer-reviewed peptide literature and translating it into calm, cited analysis. We do not sell peptides, recommend peptides, or tell readers what to administer. We describe what has been measured, by whom, at what scale, with what effect size.

Compound reviews are signed off by Dr. Priya Narang, MD, MPH (endocrinologist) and Dr. Marcus Haley, PharmD, BCPS (board-certified clinical pharmacist). Both hold verifiable state-board licenses and have signed editorial-independence letters with us. See the full editorial board →

Adjacent in the literature.

Compounds · Compound profile

BPC-157, What the Evidence Shows

Evidence Ledger for BPC-157: 50+ preclinical studies, 1 human pilot (Chang 2014, n=12), 1 active Phase trial, FDA removed from 503A list in 2023.

16 min read

Compounds · Compound profile

TB-500, The Field Guide

TB-500 vs Thymosin Beta-4 (same compound), mechanism, the preclinical tendon and recovery literature, and where the human data is thin.

14 min read

Compounds · Compound profile

GHK-Cu, Evidence and Hype

Copper peptide signaling, the topical RCT evidence for hair and skin, and the gap between topical and injectable claims.

13 min read

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