Peptides for anxiety: selank, semax and the evidence gap

What selank and semax are

Both peptides come from the same Russian research tradition and share a design trick. Selank is seven amino acids: tuftsin, an immune peptide the body makes, with a Pro-Gly-Pro tail added to slow its breakdown. Semax is also seven amino acids, built from a fragment of ACTH, the stress hormone, with the same Pro-Gly-Pro tail. Both are approved medicines in Russia, selank for generalised anxiety and adjustment disorders and semax as nasal drops used in stroke and optic-nerve disease, and neither is approved by the FDA or the EMA, as our entries on selank and semax record.

Online, selank is sold as a non-sedating anxiety peptide and semax as a nootropic for calm focus, usually as nasal sprays or powders labelled for research use. The pitch is attractive: relief without the drowsiness or dependence associated with older anti-anxiety drugs. Whether the evidence supports that pitch is the question this article answers.

Selank: what the anxiety trials found

Selank's clinical case rests on a handful of Russian studies. The most cited compared it with medazepam, a benzodiazepine, in 62 patients with generalised anxiety disorder or neurasthenia: anti-anxiety effects on the Hamilton, Zung and clinical global scales were similar, and selank also reduced fatigue (comparative trial) ¹. In 60 patients with phobic-anxiety and somatoform disorders compared with phenazepam, another benzodiazepine, selank had a pronounced anti-anxiety effect that lasted a week after the last dose (comparative trial) ². Added to phenazepam in 70 patients, it made the benzodiazepine's benefit arrive sooner and reduced its effects on attention and memory (comparative trial) ³.

Those are real clinical observations, but none is a placebo-controlled trial, and anxiety improves substantially on placebo in most trials. Showing that selank did about as well as a benzodiazepine in a small study cannot separate a drug effect from the improvement that happens with time, attention and expectation. A 2021 US review of GABA-acting sedatives described selank as a poorly studied Russian drug with GABA-related effects, sold to US consumers as a dietary supplement (review) ⁴.

The rest of selank's literature is mechanism and animals: changes in GABA-related genes and enkephalin breakdown, and anti-anxiety effects in rodents that appeared only in strains that start out more anxious (animal study) ⁵.

Semax: not an anxiety drug

Semax is often bundled with selank, but its human studies are not about anxiety. They are small Russian studies in stroke, optic-nerve disease and other conditions, few described as randomised. In 110 stroke patients, adding two 10-day courses of semax during rehabilitation was associated with higher BDNF levels and better daily-living scores (comparative study) ⁶. In 24 healthy adults, a single nasal dose changed resting brain-network activity on fMRI compared with placebo (randomised study) ⁷, and a 52-person study comparing selank, semax and placebo found differences in amygdala connectivity (randomised study) ⁸.

A brain-scan change in healthy volunteers is not a treatment effect in anxious patients, however interesting it is for understanding how these peptides act on the brain. When FDA's compounding advisers reviewed semax in July 2026, the uses its staff evaluated were cerebral ischaemia, migraine and trigeminal neuralgia, not anxiety (FDA meeting page) ⁹. The committee narrowly recommended it for the 503A list; FDA has not acted, so it cannot lawfully be compounded in the US as of October 4, 2026, as our guide to the vote explains.

The evidence gap, explained

The difference between these studies and what Western regulators require is not about where they were done. It is about design. To approve an anxiety drug, regulators expect randomised, double-blind trials against placebo, large enough to detect a modest effect and long enough to show it lasts, with pre-specified outcomes. Selank's trials are comparisons with benzodiazepines in a few dozen patients each; semax has no anxiety trials at all.

Placebo matters more in anxiety than in many conditions, and it is the single biggest reason small comparative studies mislead. Symptoms fluctuate, people often seek treatment at their worst and improve afterwards whatever they take, and expectation itself reduces anxiety. Without a placebo group, a trial cannot tell how much of the improvement the drug caused. That is why an equivalence result against a benzodiazepine, in a small open or partly blinded study, falls short.

The mechanism story, and its limits

Selank's proposed mechanism is more developed than its clinical evidence. In blood samples, people with generalised anxiety had a markedly shortened half-life of enkephalins, the body's own calming opioid peptides, and lower activity of the enzymes that break them down, while people with panic disorder did not; selank slowed enkephalin breakdown in those samples (laboratory study in patients' blood) ¹⁰. In the medazepam trial, enkephalin measures shifted with treatment, mostly in the generalised-anxiety patients (comparative trial) ¹. In blood cells from patients with depression, selank suppressed the gene for IL-6, an inflammatory signal (laboratory study) ¹¹.

Semax's most cited finding is in rats: a single nasal dose raised BDNF, a growth factor for nerve cells, in the hippocampus by up to 1.4 times (animal study) ¹². BDNF is linked to mood and learning, which is where the calm-focus marketing comes from. But a growth-factor change in a rat brain is several steps from an anti-anxiety effect in people.

The withdrawal studies in animals

Some of selank's most striking results are in rats withdrawn from alcohol or morphine. In rats that had drunk alcohol as their only fluid for 24 weeks, one injection eliminated withdrawal anxiety in two behavioural tests (animal study) ¹³. In morphine-dependent rats, one injection cut the withdrawal score by about 40%, slightly less than diazepam (animal study) ¹⁴. These findings are sometimes cited online as reasons to use selank during alcohol or opioid withdrawal. Withdrawal from either can be medically dangerous, and no human trial supports using selank for it; it needs supervised medical care.

How to judge an anxiety study

• Was there a placebo group? Without one, improvement cannot be attributed to the treatment.
• Was it double-blind? Anxiety ratings are subjective; if patients or raters know the treatment, expectations colour the scores.
• How many patients, for how long? A few dozen people over weeks can show a signal, not a reliable effect or long-term safety.
• Who was studied? Results in healthy volunteers, rats or blood cells do not show benefit for anxious people.

Selank's trials fail the first test, semax has none in anxiety, and the approved options pass all four.

Sold as supplements in the US

The 2021 US review placed selank alongside phenibut, another Russian drug sold to US consumers as a dietary supplement, and noted rising poison-centre calls about phenibut (review) ⁴. Being sold that way did not involve any safety review. A product's presence on a supplement shelf or website says nothing about whether it has been tested for safety or what it contains.

What works for anxiety

The approved options have a very different evidence base. A 2019 network meta-analysis in The Lancet pooled 89 randomised trials with 25,441 people with generalised anxiety disorder. Duloxetine, pregabalin, venlafaxine and escitalopram were more effective than placebo with relatively good acceptability; quetiapine had the largest effect but was poorly tolerated, and benzodiazepines and paroxetine were effective but also poorly tolerated (meta-analysis) ¹⁵.

Psychological treatment has placebo-controlled evidence too. A 2018 meta-analysis of randomised trials comparing cognitive behavioural therapy with placebo conditions found a moderate effect on the target anxiety disorder, with nearly three times the odds of response, and large effects for generalised anxiety, obsessive-compulsive disorder and acute stress disorder (meta-analysis) ¹⁶. CBT has the added advantage of no drug side effects, and its skills can be used long after treatment ends.

Why the benzodiazepine comparison matters

Selank is often marketed as a benzodiazepine alternative without the sedation or dependence. The Russian trials hint at fewer side effects than phenazepam (comparative trial) ³, but they are too small and short to show anything about dependence or withdrawal, which develop over months. The 2019 meta-analysis found benzodiazepines effective but poorly tolerated compared with placebo (meta-analysis) ¹⁵. A peptide that performed like a benzodiazepine in a short trial has not shown it avoids the problems that limit benzodiazepines.

What a Russian approval does and does not tell you

Selank's and semax's Russian approvals are real and are recorded in our dataset (dataset) ¹⁷. They show that a national regulator accepted the evidence submitted to it. They do not show that the evidence would satisfy the FDA or the EMA, which would ask for placebo-controlled trials of the kind described above, and we could not find such trials in the published literature. The practical consequence is that a European or American clinician has no approved product to prescribe and no trial results of the standard they are trained to rely on.

The same gap appears with other peptides developed and marketed mainly in Russia, such as the short bioregulator peptides from the St Petersburg group. Our encyclopedia records each compound's status by country so the distinction stays visible.

Nasal sprays and the dose question

Selank and semax are usually sold as nasal sprays, following the Russian products. In mice, the route mattered: daily nasal or injected selank for five days produced anti-anxiety and memory effects only in a strain that starts out more anxious, and only the injected form raised GABA-receptor binding sites in the brain (animal study) ⁵. That makes it hard to know what a given spray, at a given dose, does in a person, and no placebo-controlled human trial has settled a dose for anxiety.

Combining with other medicines

The one Russian study of selank added to a benzodiazepine reported that the combination worked faster and with fewer memory and attention effects than phenazepam alone (comparative trial) ³. That is not a reason to combine products at home. Adding anything with proposed effects on GABA or enkephalin systems to prescribed sedatives, antidepressants, alcohol or opioids carries interaction risks that have not been studied, and the prescriber of those medicines needs to know.

Risks of trying anxiety peptides

Selank and semax sold online are research-grade products outside any quality control; testing of comparable gray-market peptides has found missing, wrong or contaminated contents, as our marketplace article describes. No dose has been established in a placebo-controlled trial, and long-term safety is unknown outside the Russian clinical experience, which is not reported in detail in the literature we could read.

Anxiety can also be a symptom of other conditions, including thyroid disease, heart rhythm problems, depression or substance use. Self-treating with an unproven peptide can delay a diagnosis. And anyone taking prescribed anxiety or mood medicines should not add a product with proposed GABA-related effects without talking to their prescriber.

What a fair trial of selank would look like

It is possible that selank has a real anti-anxiety effect; small comparative studies are not evidence that it does not. The way to find out is straightforward and has not been done in the published literature: a randomised, double-blind trial in a few hundred people with generalised anxiety disorder, comparing selank with placebo and ideally with an established drug such as escitalopram, over at least eight weeks, with a pre-registered primary outcome and follow-up for withdrawal effects. That is the standard the approved medicines in the 2019 meta-analysis met (meta-analysis) ¹⁵.

Until such a trial exists, the honest position is uncertainty, not either 'it works' or 'it doesn't'. What is not uncertain is that a research-grade spray bought online is not the Russian pharmaceutical product, and carries the quality risks of any unregulated peptide.

Side by side

• Selank: approved in Russia; three small trials against or alongside benzodiazepines (60-70 patients each); no placebo-controlled trial found; not lawfully available as a medicine in the US.
• Semax: approved in Russia; small studies in stroke and other conditions; no anxiety trials; backed by FDA's advisers in 2026 for other uses, with FDA yet to act.
• Approved GAD medicines: 89 randomised trials, 25,441 patients, several drugs better than placebo with good acceptability.
• CBT: placebo-controlled trials showing moderate to large effects across anxiety disorders.

If you are struggling with anxiety

1. Talk to a clinician. They can check for physical causes and help decide between psychological therapy, medicine or both.
2. Ask about CBT, which is available in person, by telehealth and through structured digital programmes.
3. If medicine is suggested, ask how long it takes to work, what side effects to expect and how it will be stopped if needed.
4. If you are in crisis or having thoughts of harming yourself, contact emergency services or, in the US, call or text 988, the Suicide and Crisis Lifeline.

Questions to ask about an anxiety peptide

• Has it beaten placebo in a randomised, double-blind trial in people with my kind of anxiety?
• How large was the trial, and how long did it last?
• What is known about dependence or withdrawal after months of use?
• Where would it come from, and who has checked what is in it?

How it adds up (as of October 4, 2026)

Selank and semax are approved medicines in Russia, but their evidence for anxiety does not meet the standard Western regulators use. Selank's human trials are small comparisons with benzodiazepines rather than placebo, and a 2021 US review called it poorly studied; semax has no anxiety trials and was reviewed by FDA for other uses. Neither is approved in the US or EU, and neither can lawfully be compounded in the US as of October 4, 2026. Approved medicines for generalised anxiety and cognitive behavioural therapy have beaten placebo in trials with thousands of patients. For someone struggling with anxiety now, those are the treatments to start with; for selank, the open question is whether anyone will run the placebo-controlled trial that would settle it.

Frequently asked questions

Is selank good for anxiety?

Small Russian trials found it worked about as well as benzodiazepines, but none was placebo-controlled, so its true effect is unknown; a 2021 US review called it poorly studied.

Is selank approved?

It is approved in Russia for generalised anxiety and adjustment disorders, but not by the FDA or the EMA.

Does semax help anxiety?

Its human studies are in stroke and other conditions, not anxiety; FDA's 2026 review evaluated it for cerebral ischaemia, migraine and trigeminal neuralgia.

What is the best peptide for anxiety?

None has placebo-controlled evidence for anxiety. Approved medicines and cognitive behavioural therapy have far stronger data.

Is selank a benzodiazepine alternative?

It performed similarly to benzodiazepines in small, short Russian trials, which cannot show whether it avoids dependence or withdrawal.

Related on Grey Peptides

• Selank
• Semax
• The July 2026 PCAC votes
• Peptides for sleep

Sources

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2. Medvedev, V. E., et al. (2014). [A comparison of the anxiolytic effect and tolerability of selank and phenazepam in the treatment of anxiety disorders]. Zh Nevrol Psikhiatr Im S S Korsakova, 114(7), 17-22. PMID: 25176261
3. Medvedev, V. E., et al. (2015). [Optimization of the treatment of anxiety disorders with selank]. Zh Nevrol Psikhiatr Im S S Korsakova, 115(6), 33-40. PMID: 26356395
4. Doyno, C. R., et al. (2021). Sedative-Hypnotic Agents That Impact Gamma-Aminobutyric Acid Receptors: Focus on Flunitrazepam, Gamma-Hydroxybutyric Acid, Phenibut, and Selank. J Clin Pharmacol, 61 Suppl 2, S114-S128. PMID: 34396551
5. Vasil'eva, E. V., et al. (2016). [COMPARISON OF PHARMACOLOGICAL EFFECTS OF HEPTAPEPTIDE SELANK AFTER INTRANASAL AND INTRAPERITONEAL ADMINISTRATION TO BALB/c AND C57BL/6 MICE.]. Eksp Klin Farmakol, 79(9), 3-11. PMID: 29787664
6. Gusev, E. I., et al. (2018). [The efficacy of semax in the tretament of patients at different stages of ischemic stroke]. Zh Nevrol Psikhiatr Im S S Korsakova, 118(3. Vyp. 2), 61-68. PMID: 29798983
7. Lebedeva, I. S., et al. (2018). Effects of Semax on the Default Mode Network of the Brain. Bull Exp Biol Med, 165(5), 653-656. PMID: 30225715
8. Panikratova, Y. R., et al. (2020). Functional Connectomic Approach to Studying Selank and Semax Effects. Dokl Biol Sci, 490(1), 9-11. PMID: 32342318
9. Food and Drug Administration. July 23-24, 2026 Meeting of the Pharmacy Compounding Advisory Committee: substances and uses evaluated; read October 4, 2026. Source
10. Zozulya, A. A., et al. (2001). The inhibitory effect of Selank on enkephalin-degrading enzymes as a possible mechanism of its anxiolytic activity. Bull Exp Biol Med, 131(4), 315-7. PMID: 11550013
11. Uchakina, O. N., et al. (2008). [Immunomodulatory effects of selank in patients with anxiety-asthenic disorders]. Zh Nevrol Psikhiatr Im S S Korsakova, 108(5), 71-5. PMID: 18577961
12. Dolotov, O. V., et al. (2006). Semax, an analog of ACTH(4-10) with cognitive effects, regulates BDNF and trkB expression in the rat hippocampus. Brain Res, 1117(1), 54-60. PMID: 16996037
13. Kolik, L. G., et al. (2014). Efficacy of peptide anxiolytic selank during modeling of withdrawal syndrome in rats with stable alcoholic motivation. Bull Exp Biol Med, 157(1), 52-5. PMID: 24913576
14. Konstantinopolsky, M. A., et al. (2022). Selank, a Peptide Analog of Tuftsin, Attenuates Aversive Signs of Morphine Withdrawal in Rats. Bull Exp Biol Med, 173(6), 730-733. PMID: 36322304
15. Slee, A., et al. (2019). Pharmacological treatments for generalised anxiety disorder: a systematic review and network meta-analysis. Lancet, 393(10173), 768-777. PMID: 30712879
16. Carpenter, J. K., et al. (2018). Cognitive behavioral therapy for anxiety and related disorders: A meta-analysis of randomized placebo-controlled trials. Depress Anxiety, 35(6), 502-514. PMID: 29451967
17. Grey Peptides dataset (assets/peptides-data.json), selank and semax rows: approval details recorded as approved in Russia, not approved by the FDA or EMA; read October 4, 2026.

Educational information, not medical advice. Each dose in this guide names its source, an approved label or a published study. None is a recommendation for you. An unapproved compound has no established safe or effective human dose, and products sold for “research use only” are not made or tested for people. Talk to a doctor before acting on anything on this site, including before you start, stop or change any medicine or dose.