Semax
Derived from ACTH, minus the hormonal part. Registered in Russia since 1994 for stroke and cognitive conditions. Reported to raise BDNF substantially.
Selank
Derived from tuftsin, a fragment of an antibody. A registered prescription anxiolytic in Russia, taken as a nasal spray.
Side-by-Side Comparison
In Russian clinical practice, given in acute ischemic stroke and for cognitive conditions. Marketed in the West as a nootropic, which is not what it is registered for.
Registered in Russia as a prescription anxiolytic. The claimed advantage is calming without the sedation, tolerance, and dependence of benzodiazepines.
Amino acids 4 to 7 of ACTH plus a stabilising tail. The modification keeps the brain-active portion while removing the part that triggers cortisol release.
Built from tuftsin, a four-amino-acid fragment of immunoglobulin G, with a stabilising sequence added so it lasts long enough to be useful.
Reported to raise BDNF and its receptor in the hippocampus, and to protect neurons during oxygen deprivation, which is the basis for the stroke use.
Affects expression of GABA-related genes rather than binding the receptor directly, and slows the breakdown of enkephalins, your own opioid-like peptides.
The most rigorous published human study enrolled 110 post-stroke patients but was neither randomized nor placebo-controlled, from a single Russian group. Stroke patients recover substantially on their own over the same window.
Russian clinical studies report benefit, but are generally small, published in Russian-language journals, and frequently lack blinding or placebo controls. Anxiety is highly placebo-responsive, which makes unblinded evidence especially weak.
No randomized controlled trial meeting Western regulatory standards has been published for any indication.
Same. Neither compound has been evaluated under the standards a US or EU regulator would require.
Registered in Russia since 1994. On 24 July 2026 an FDA advisory committee voted to recommend it for the permitted 503A compounding list, for selected neurologic uses. Advisory and non-binding.
Registered in Russia. Placed in FDA Category 2 in 2023 and removed in September 2024, but never added to the permitted list, and not among the peptides reviewed in July 2026.
Russian stroke protocols used up to 6,000mcg per day intranasally. Community nootropic use is far lower, typically 300 to 900mcg daily.
Russian clinical use is typically 250 to 300mcg daily intranasally, in courses of 10 to 14 days.
These two get discussed as a pair, and often stacked, but they were built for different jobs.
**Semax** is a stroke and neuroprotection drug in Russia. Its headline mechanism, raising BDNF, is a real and well-validated target for cognition and mood. In the West it is sold as a nootropic, which is not what it is registered for and not what it has been studied for.
**Selank** is an anxiolytic. Its pitch is real anxiety relief without the sedation, tolerance, and dependence that come with benzodiazepines, which is a genuinely valuable thing if it holds up.
The problem is identical for both, and it is not a small one. Neither has ever been tested in a randomized controlled trial meeting Western regulatory standards, for any indication. The supporting research is concentrated in Russian-language literature from a small number of affiliated groups, is frequently unblinded and uncontrolled, and has barely been replicated independently.
That is not the same as saying they do not work. Decades of Russian clinical use without a major safety scandal counts for something. It means that if they work, we do not have the kind of evidence that would let us know it, and both anxiety and cognitive performance are among the most placebo-responsive things anyone measures.
If you are choosing between them, choose on the target: anxiety points to Selank, post-stroke or neuroprotective interest points to Semax. Just go in knowing you are running an experiment, not following evidence.
Which Is Right for You?
- Your interest is neuroprotection or post-stroke recovery, discussed with a neurologist
- You want the compound with a defined mechanism on BDNF
- You are researching what Russian clinical practice actually uses it for
- Anxiety is the target rather than cognition
- You want something claimed not to cause sedation, tolerance, or dependence
- You have already tried treatments with real trial evidence behind them
Important Note
This comparison is for educational purposes only and should not replace medical advice. The best medication for you depends on your individual health profile, medical history, and personal circumstances. Always consult with a healthcare provider who can evaluate your specific situation before starting any medication.
Frequently Asked Questions
What is the difference between Semax and Selank?
Different origins and different targets. Semax comes from ACTH and is registered in Russia for stroke and cognitive conditions. Selank comes from tuftsin, a fragment of an antibody, and is registered in Russia as an anti-anxiety medication. Both are intranasal, both are Russian-registered, and both share the same core problem: no randomized controlled trial meeting Western standards has been published for either.
Can you stack Semax and Selank?
People routinely do, on the theory that one handles focus and the other handles anxiety. The combination has never been studied. Given that neither compound individually has been tested to Western trial standards, stacking them means running two uncontrolled experiments at once and being unable to tell which is responsible for anything you notice.
Are Semax and Selank safe?
Both are generally reported as well tolerated across decades of Russian clinical use, with nasal irritation the most commonly mentioned effect. That is worth something, but "no reported problem" and "demonstrated safety" are different standards. Systematic side effect data outside Russian clinical experience does not exist, and interactions with psychiatric medication have not been studied. If you take anything for mood or anxiety, tell your prescriber.
Which is better for focus and cognition?
Semax, on mechanism, since it is the one with reported BDNF effects and neuroprotective activity. But no controlled human trial has tested Semax for cognitive performance in healthy people, so the honest answer is that nobody knows. Selank can indirectly improve cognitive performance by reducing anxiety, which makes untangling a direct nootropic effect harder rather than easier.
Why is the evidence so weak if they have been used for decades?
Both were developed and studied in Russia under a different regulatory tradition, and most of the research is published in Russian-language journals by a small number of affiliated research groups. Independent replication under blinded, placebo-controlled conditions is how the field separates real effects from lab-specific artifacts, and for these two it has barely happened.