Semax and Selank are the two best-known peptides to come out of Russian neuroscience, and they are constantly mentioned together. Both were developed at the same institute, both are given as nasal drops, and both share a protective Pro-Gly-Pro tail. But they are built for different jobs: Semax leans toward focus, memory and brain protection, while Selank leans toward calm and anxiety relief.
This guide compares the two head to head — how they work, what the evidence says, how they differ, and which one matches which goal. For the full picture on each, see our Semax guide and Selank guide.
Quick Comparison
| Semax | Selank | |
|---|---|---|
| Built from | ACTH(4–7) fragment | Tuftsin (immune peptide) |
| Main goal | Focus, memory, brain protection | Anxiety, stress, calm |
| Key mechanism | Raises BDNF; dopamine and serotonin; neuroprotection | GABA and serotonin systems; enkephalins; BDNF |
| Feel reported | Alert, stimulating | Calm without sedation |
| Best-studied use | Stroke recovery, cognition | Generalized anxiety |
| Form | Nasal drops (Russia) | Nasal drops (Russia) |
| Approved? | Russia only | Russia only |
What They Share
Both peptides were developed at the Institute of Molecular Genetics of the Russian Academy of Sciences, and both use a Pro-Gly-Pro tail that slows breakdown in the body. Both are delivered as nasal drops, which skips the digestive system and may give more direct access to the brain. And both are registered medicines in Russia but are not approved in the US, EU or UK, where they are sold as research compounds.
They even overlap at the molecular level: both inhibit the enzymes that break down enkephalins, the body's natural opioid peptides tied to stress and emotional balance.
How They Differ
Semax: the focus and recovery peptide
Semax is built on a fragment of ACTH. Its signature effect in animal research is raising BDNF (brain-derived neurotrophic factor) and its receptor in the hippocampus — the growth-factor signaling behind learning and memory. It also modulates dopamine, which is why users often describe it as alert or mildly stimulating. Its strongest clinical evidence is in ischemic stroke recovery, where Russian studies report better neurological outcomes.
Selank: the calm and anxiety peptide
Selank is built on tuftsin. Rather than acting as a stimulant, it works through the brain's GABA system — the same calming network benzodiazepines act on — but in a different way that avoided sedation in studies. Its best-studied use is generalized anxiety, where one Russian trial found it comparable to the benzodiazepine medazepam, with less drowsiness. Because of its tuftsin origin it also touches immune signaling.
Which One Fits Which Goal
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Focus, memory, mental fatigue: Semax is the one studied for cognition and attention.
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Anxiety and stress: Selank is the one designed and studied as an anxiety treatment.
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Brain protection after injury: Semax has the stroke-recovery evidence.
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Calm without feeling drugged: Selank's profile is non-sedating.
This is also why the two are so often discussed as a pair: the common idea is that Selank handles the anxiety side while Semax handles focus. No clinical trial has tested them together, so that combination is based on how they work individually, not on evidence that stacking them is safe or effective.
Safety at a Glance
Both are described as well tolerated in Russian clinical use, with side effects mostly limited to the nasal route — irritation, dryness, occasional headache. Neither showed dependence in short studies, but those studies were small and short-term, so long-term safety outside Russia is not established. Anyone taking psychiatric or neurological medication, or who is pregnant or breastfeeding, should not use either without a physician.
Legal Status
Neither is FDA approved. In July 2026, an FDA advisory committee recommended Semax for compounding, but Selank was not among the peptides reviewed. That recommendation is advisory only and does not make Semax a legal compounded or approved drug yet. Both remain registered medicines in Russia and unapproved elsewhere.
Frequently Asked Questions
Can you take Semax and Selank together?
They are often discussed as a stack — Selank for calm, Semax for focus — but no clinical trial has tested the combination, so its safety and effects together are unknown.
Which is better for anxiety, Semax or Selank?
Selank is the one developed and studied specifically as an anti-anxiety peptide. Semax is oriented toward focus, memory and brain protection.
Are Semax and Selank the same thing?
No. They come from the same institute and share a Pro-Gly-Pro tail, but Semax is based on an ACTH fragment (cognition, stroke) and Selank is based on tuftsin (anxiety).
Are they legal in the US?
Neither is FDA approved. Semax received an advisory compounding recommendation in July 2026, but that is not the same as approval, and Selank was not reviewed.
Disclaimer
This article is for educational and informational purposes only. Neither Semax nor Selank is approved by the FDA. Information here reflects Russian clinical practice and published research and is not a recommendation for use. Nothing here is medical advice. The Peptide Library is operated in connection with ZenoPeps. Research products are not intended for human consumption.