Selank Side Effects and Safety: What Russian Trials Report and What Western Data Lack

Selank has no well-characterized side-effect profile in the English-language literature. Its human data come from small Russian trials in anxiety disorders, which report it as well tolerated and, in one study, as reducing the side effects of a benzodiazepine, but whose published abstracts give no adverse-event tables. Western reviewers describe Selank as poorly studied, there are no Western randomized trials, and the main practical concerns are possible interactions with sedatives, unknown long-term effects, and the quality of unregulated product.

This guide explains what is and is not known, how strong each piece of evidence is, and what prescribers should consider before use.

Educational content for licensed healthcare professionals. Not medical advice; dosing and treatment decisions belong to the prescribing clinician.

What Selank Is

Selank is a synthetic seven-amino-acid peptide (Thr-Lys-Pro-Arg-Pro-Gly-Pro). It is an analog of tuftsin, a naturally occurring immunomodulatory tetrapeptide, extended with a Pro-Gly-Pro tail that slows its breakdown [1][2]. It was developed in Russia as an anxiolytic and is registered there as a medicine, which does not confer US approval. Its proposed mechanisms include allosteric modulation of GABA-A receptor binding, effects on enkephalin-degrading activity, and immune cytokine changes [2][3][4]. See the Selank library page for background, and our comparison of Semax and Selank for how it differs from its sister peptide.

Selank Side Effects: Evidence Table

What the Russian Clinical Studies Report

The human evidence is a handful of small, mostly open or comparative studies published in Russian journals:

• Generalized anxiety disorder and neurasthenia (n = 62). Selank was compared with the benzodiazepine medazepam. Anxiolytic effects were similar, and Selank also showed "antiasthenic and psychostimulant" effects. Patients had low levels of a leu-enkephalin measure that rose during treatment [3].
• Anxiety disorders (n = 60). Selank was compared with phenazepam. The authors report a pronounced anxiolytic and mild nootropic effect lasting a week after the last administration and better quality of life; the abstract compares tolerability but does not list specific adverse events [5].
• Add-on to phenazepam (n = 70). Adding Selank to phenazepam reduced the benzodiazepine's undesirable effects, including attention and memory impairment, asthenia, sedation, sexual dysfunction and orthostatism, both during treatment and after withdrawal [6].
• Immune markers. In patients with anxiety-asthenic disorders, two weeks of Selank shifted the Th1/Th2 cytokine balance [4].

These studies are small, not placebo-controlled in the Western regulatory sense, and published mostly in Russian with English abstracts only. They are consistent with good short-term tolerability, but they cannot establish the frequency of uncommon adverse effects or anything about long-term use.

The GABA Interaction Question

Laboratory work suggests Selank acts as an allosteric modulator of GABA-A receptor binding, and that its interaction with benzodiazepines is "not cumulative" and differs from either drug alone; it blocked the modulatory activity of diazepam and olanzapine in that model [2]. In rats under chronic mild stress, combining Selank with diazepam was the most effective condition for reducing anxiety [9].

Clinically, the Russian add-on study suggests the combination may reduce benzodiazepine side effects [6]. The opposite risk, additive sedation, has not been ruled out in any Western study. A 2021 US review of GABA-acting sedative-hypnotics listed Selank with phenibut as "poorly studied Russian drugs with GABAergic mechanisms" sold to US consumers, and called for abuse-potential evaluation before public access [7]. Prescribers should treat co-use with benzodiazepines, Z-drugs, alcohol, gabapentinoids or opioids as an untested combination.

Who Should Avoid Selank

• Pregnancy and breastfeeding, for which there are no data.
• Children and adolescents.
• Patients on benzodiazepines, other sedatives, or with alcohol or sedative use disorders, unless the combination is deliberately supervised.

• Patients with autoimmune disease or on immunomodulating therapy, given the reported cytokine effects [4] and the tuftsin lineage [1].
• Patients with unstable psychiatric illness who need an evidence-based treatment plan.
• Competitive athletes. Non-approved substances fall within WADA's prohibited categories.

Monitoring Considerations for Prescribers

• Document all CNS-active medications and alcohol use before starting, and reassess when they change.
• Track anxiety, sleep and alertness with a simple validated scale so benefit and adverse effects can be separated from baseline symptoms.
• Ask about sedation, activation or insomnia at follow-up, given reports of both anxiolytic and stimulant-like effects.
• Verify product identity and purity with the dispensing pharmacy; seized preparations have contained these peptides without clear labeling [8].

Regulatory Status (October 2026)

Selank is not FDA-approved. It does not appear in any category on FDA's 503A bulk-substance category list (updated May 14, 2026), so it has no Category 1 interim status; confirm availability with your compounding pharmacy and check the FDA Peptide Status Tracker for changes. Selank was not among the peptides considered at the July 2026 PCAC meeting; its sister peptide Semax was, and the committee voted 8–5 (1 abstention) to recommend adding Semax to the 503A Bulks List. That vote is advisory, and Semax is not on the list until FDA completes rulemaking.

Frequently Asked Questions

What are the side effects of Selank?

Small Russian studies describe Selank as well tolerated in anxiety disorders, but their published abstracts do not list adverse-event rates. Reported effects include activating, "psychostimulant" effects and immune cytokine changes. Long-term and rare adverse effects are unknown.

Can Selank be taken with benzodiazepines?

One Russian study found that adding Selank to phenazepam reduced the benzodiazepine's side effects. Laboratory data show the two interact at GABA receptors in complex ways. The combination has not been studied in Western trials and should be treated as untested.

Is Selank addictive?

No study has evaluated Selank's abuse or dependence potential. A US toxicology review grouped it with poorly studied GABAergic agents and recommended that abuse potential be assessed.

Is Selank approved in Russia?

Selank is registered as a medicine in Russia, where it was developed. Russian registration does not mean FDA approval; in the US it is not an approved drug.

Is Selank safer than Semax?

There is no head-to-head safety study. The two peptides target different systems, and both have limited Western data. See our Semax and Selank comparison and the Semax library page.

Newtropin does not prescribe, compound, or dispense. We connect licensed providers with licensed 503A compounding partners; prescribers can start at For Providers. For the wider category, see our nootropic peptides guide.

References

1. Siebert A, et al. Tuftsin - properties and analogs. Curr Med Chem. 2017;24(34):3711-3727. PubMed
2. Vyunova TV, et al. Peptide-based anxiolytics: the molecular aspects of heptapeptide Selank biological activity. Protein Pept Lett. 2018;25(10):914-923. PubMed
3. Zozulia AA, et al. [Efficacy and possible mechanisms of action of a new peptide anxiolytic selank in the therapy of generalized anxiety disorders and neurasthenia]. Zh Nevrol Psikhiatr Im S S Korsakova. 2008;108(4):38-48. PubMed
4. Uchakina ON, et al. [Immunomodulatory effects of selank in patients with anxiety-asthenic disorders]. Zh Nevrol Psikhiatr Im S S Korsakova. 2008;108(5):71-5. PubMed
5. Medvedev VE, et al. [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. 2014;114(7):17-22. PubMed
6. Medvedev VE, et al. [Optimization of the treatment of anxiety disorders with selank]. Zh Nevrol Psikhiatr Im S S Korsakova. 2015;115(6):33-40. PubMed
7. Doyno CR, et al. Sedative-hypnotic agents that impact gamma-aminobutyric acid receptors: focus on flunitrazepam, gamma-hydroxybutyric acid, phenibut, and selank. J Clin Pharmacol. 2021;61 Suppl 2:S114-S128. PubMed
8. Vanhee C, et al. The occurrence of putative cognitive enhancing research peptides in seized pharmaceutical preparations: an incentive for controlling agencies to prepare for future encounters of the kind. Drug Test Anal. 2020;12(3):371-381. PubMed
9. Kasian A, et al. Peptide Selank enhances the effect of diazepam in reducing anxiety in unpredictable chronic mild stress conditions in rats. Behav Neurol. 2017;2017:5091027. PubMed