Comparison
Semax vs. Selank
Semax or Selank – what is actually proven about the Russian peptides?
The short answer
Selank has more human data: three Russian studies with 62, 60 and 70 patients with anxiety disorders found an anxiolytic effect similar to that of benzodiazepines, and as an add-on to phenazepam its side effects decreased. Semax's strength is the mechanism: the rise in BDNF and NGF has been shown preclinically at several institutions. Its clinical studies on stroke and reduced blood flow to the brain, however, were neither randomised nor placebo-controlled, and there are no human studies on NA-Semax amidate, the version mostly sold. Both lack a placebo-controlled patient trial and an independent replication outside Russia. There is no direct comparison; one can only put the studies side by side. Neither is approved in Germany – the decision belongs in medical hands.
The numbers side by side
| Axis | Semax | Selank | Difference |
|---|---|---|---|
| Human evidenceHow much and how good the data in humans are | 3 | 4 | Selank better studied |
| MechanismHow well the chain of action is understood | 4 | 4 | even |
| Safety dataHow well safety has been studied – not how safe it is | 2 | 3 | Selank better studied |
| Hype gap10 means: the advertising stays level with the data | 2 | 2 | even |
| Track record of useHow much documented use in humans exists – does not measure whether it works | 5 | 4 | Semax in use longer |
| Rating | Hype far ahead of evidence · Thin human evidence | ||
“Track record of use” measures how long and how widely something has been used in humans – not whether it works. The BK-Score is a subjective assessment by Biohacking Kompakt based on published scoring rules (German). It is not a scientific rating, not the consensus of a professional society and not a medical recommendation.
Why these numbers
Semax
Registered as a medicine in Russia but not in the West – and the evidence explains why: the clinical studies that can be found, such as Gusev et al. 1997 with 30 patients after ischaemic stroke versus 80 controls and 2005 with 187 patients with chronic cerebral hypoperfusion, are almost exclusively in Russian and come essentially from the same two research groups. No independent double-blind replication in an international journal was found. BDNF elevation as the mechanism of action has been shown preclinically and measured in humans in only one non-randomised study (Gusev 2018, BDNF in blood); a clinical benefit resulting from it has not. No Western pharmacovigilance. And the evidence applies to Semax, not to the NA-Semax amidate commonly sold. The only placebo-controlled human study found: Lebedeva 2018 (24 healthy subjects, 14 Semax/10 placebo, fMRI after 5 and 20 min, change in the default mode network; surrogate, developer as co-author). FDA briefing 2026: ischaemia-related literature only in Russian, uncontrolled migraine study, “insufficient evidence of effectiveness”, no acute or repeat-dose toxicity studies submitted.
Selank
Unusually many human data for a scene peptide, but small and almost entirely from Russian-language journals: Zozulia et al. 2008 compared Selank with medazepam in 62 patients with anxiety disorders, Medvedev et al. 2014 with phenazepam in 60 patients, Medvedev et al. 2015 phenazepam alone versus phenazepam plus Selank in 70 patients. The anxiolytic effect was comparable; as an add-on, benzodiazepine side effects decreased. The comparison was always against a benzodiazepine, not against placebo – a design that cannot reliably prove efficacy. No independent Western replication was found. The GABA modulation and the BDNF involvement come from animal models. Tolerability has only been recorded short-term in these patient studies; not an approved medicine in Germany.
Frequently asked questions
What is the difference between Semax and Selank?
Both are peptides made of seven amino acids, developed in the same Moscow research environment and designed for uptake through the nose. Semax is a fragment of the hormone ACTH without its hormonally active part and is meant to raise BDNF and NGF; in Russia it has been registered since 1994 for circulatory disorders of the brain. Selank is a modified version of the immune peptide tuftsin and is approved in Russia as an anti-anxiety medicine. In the scene, Semax is seen as stimulating, Selank as calming.
Which peptide is better studied, Semax or Selank?
In humans, Selank. It was compared with benzodiazepines in three Russian studies in anxiety patients and had a similar anxiolytic effect. The clinical Semax studies were not randomised and had no placebo; the only placebo-controlled human study found is an imaging study in 24 healthy people. In the BK-Score, human evidence is 4 for Selank and 3 for Semax. Neither was tested against placebo in patient studies, and an independent replication outside Russia is missing for both.
Can you combine Semax and Selank?
The combination is common in the scene, Semax for focus and Selank for calm. That is community practice: there are no studies on the combination, and even the individual substances lack placebo-controlled patient trials. In addition, Selank contributes to diazepam's GABA binding in the lab – combining it with sedatives therefore belongs in medical hands. Neither peptide is approved in Germany.
Do Semax or Selank help healthy people with focus and stress?
There are no reliable data for either. The clinical Semax studies come from patients after stroke or with chronic reduced blood flow to the brain; the only study in healthy people measured changes in brain imaging after a single administration, not performance. The Selank data come from people with anxiety disorders; there are no studies in healthy people under stress. For both, a benefit for healthy people is so far speculation.
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Information only, not medical advice and not a usage or dosage recommendation. Prescription-only and unapproved substances belong in a doctor's hands.