Semax and Selank are the two best-known Russian "nootropic" peptides, frequently discussed together because they're often described as complementary. Semax (an ACTH fragment analog) is associated with focus, cognition, and neuroprotection; Selank (a tuftsin analog) is associated with calm and anti-anxiety effects. Both are intranasal and neither is FDA-approved.
At a glance
| Semax | Selank | |
|---|---|---|
| Derived from | ACTH(4–10) fragment analog | Tuftsin analog |
| Associated effects | Focus, cognition, neuroprotection | Calm, anti-anxiety |
| Typical route | Intranasal | Intranasal |
| Origin | Developed/used in Russia | Developed/used in Russia |
| FDA status | Not approved | Not approved |
| Western evidence | Limited independent trials | Limited independent trials |
Which is better, Semax or Selank?
They are usually described as complementary rather than competing, and the choice framing in most discussion is about which effect someone is after.
Semax is associated with focus, alertness and cognitive performance, and much of its clinical research concerns stroke recovery and neurological conditions. Selank is associated with calm and reduced anxiety, with research oriented toward anxiety states rather than cognition. People who use both typically describe Semax as the stimulating one and Selank as the settling one.
The critical caveat applies to both equally: this framing comes from the peptides' proposed mechanisms and from user reports, not from head-to-head controlled trials in healthy adults. There is no study comparing Semax against Selank, so any ranking is inference. Neither is approved in the US, the EU, or the UK.
What the research does and does not show
Both peptides were developed in Russia and both are used clinically there and in some neighbouring countries. That is a real regulatory history, and it is more than most research peptides have. But it comes with a specific limitation worth stating plainly.
The evidence base is geographically concentrated. Most of the supporting research is published in Russian-language journals and originates from a relatively small research community. Independent replication elsewhere is the normal mechanism by which findings become reliable, and for these two compounds it is largely absent. No Western regulator has reviewed either.
Most trials studied impaired brains, not healthy ones. The clinical work concerns stroke, cognitive decline, and anxiety disorders. Demonstrating an effect in a diagnosed condition is not the same as demonstrating enhancement in a healthy adult, and the two are routinely conflated in marketing.
Cognitive and mood outcomes are unusually placebo-prone. Feeling sharper or calmer is exactly the kind of outcome expectation alone reliably produces, which is why uncontrolled personal experience is weak evidence here in particular.
None of this means the compounds do nothing. It means the confident claims made for them outrun what has actually been established.
The bottom line
Bottom line: They're usually framed as a pair rather than rivals — Semax leaning toward stimulation/focus and neuroprotection, Selank toward calm and anxiety reduction. Both are used clinically in Russia but lack large independent Western trials, neither is FDA-approved, and both are typically given as nasal sprays.
Frequently asked questions
What's the difference between Semax and Selank?
Semax is generally associated with focus, cognition, and neuroprotection, while Selank is associated with calm and anti-anxiety effects. They are often described as complementary Russian nootropic peptides.
Are Semax and Selank FDA-approved?
No. Both are used as medicines in Russia but are not FDA-approved, and large independent Western clinical trials are lacking. They are sold elsewhere as research chemicals.
How are they taken?
Both are typically formulated as intranasal sprays, partly because they would be broken down if swallowed. We do not publish dosing protocols.
References
Combined peer-reviewed sources from both peptide guides. Inclusion is not endorsement.
- Dolotov OV, Karpenko EA, Seredenina TS, et al. Semax, an analogue of ACTH(4-10), increases brain-derived neurotrophic factor protein in rat basal forebrain. J Neurochem. 2006. Peer-reviewed study
- Gusev EI, Skvortsova VI, Miasoedov NF, et al. Effectiveness of semax in the acute period of hemispheric ischemic stroke. Zh Nevrol Psikhiatr Im S S Korsakova. 1997. Peer-reviewed study
- Gusev EI, Skvortsova VI, Chukanova EI. Semax in prevention of disease progression in patients with cerebrovascular insufficiency. Zh Nevrol Psikhiatr Im S S Korsakova. 2005. Peer-reviewed study
- Liu R, Chen Y, Huang H, et al. Semax peptide targets the μ opioid receptor gene Oprm1 to promote deubiquitination and functional recovery after spinal cord injury in female mice. Br J Pharmacol. 2025. Peer-reviewed study
- Sciacca MFM, Naletova I, Giuffrida ML, et al. Semax, a Synthetic Regulatory Peptide, Affects Copper-Induced Abeta Aggregation and Amyloid Formation in Artificial Membrane Models. ACS Chem Neurosci. 2022. Peer-reviewed study
- Glazova NY, Manchenko DM, Volodina MA, et al. Semax, synthetic ACTH(4-10) analogue, attenuates behavioural and neurochemical alterations following early-life fluvoxamine exposure in white rats. Neuropeptides. 2021. Peer-reviewed study
- Zozulia AA, Neznamov GG, Siuniakov TS, et al. Efficacy and mechanisms of action of the peptide anxiolytic selank in generalized anxiety disorder and neurasthenia. Zh Nevrol Psikhiatr Im S S Korsakova. 2008. Peer-reviewed study
- Kolik LG, Nadorova AV, Antipova TA, et al. Selank, peptide analogue of tuftsin, protects against ethanol-induced memory impairment by regulating BDNF. Bull Exp Biol Med. 2019. Peer-reviewed study
- Konstantinopolsky MA, Chernyakova IV, Kolik LG. Selank, a Peptide Analog of Tuftsin, Attenuates Aversive Signs of Morphine Withdrawal in Rats. Bull Exp Biol Med. 2022. Peer-reviewed study
- Kasian A, Kolomin T, Andreeva L, et al. Peptide Selank Enhances the Effect of Diazepam in Reducing Anxiety in Unpredictable Chronic Mild Stress Conditions in Rats. Behav Neurol. 2017. Peer-reviewed study
- Vyunova TV, Andreeva L, Shevchenko K, et al. Peptide-based Anxiolytics: The Molecular Aspects of Heptapeptide Selank Biological Activity. Protein Pept Lett. 2018. Peer-reviewed study
- Fomenko EV, Bobyntsev II, Ivanov AV, et al. Effect of Selank on Morphological Parameters of Rat Liver in Chronic Foot-Shock Stress. Bull Exp Biol Med. 2019. Peer-reviewed study