Is hair loss a known side effect of Selank?

Hair loss is not a commonly reported issue in the scientific literature concerning Selank. Based on currently available human and animal studies, there is no evidence to suggest that Selank directly causes hair loss, baldness, or increased shedding [1–4].

Selank is a synthetic heptapeptide derived from the naturally occurring immunomodulatory peptide tuftsin. Its amino acid sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro (TKPRPGP) [5]. Most studies have focused on its impact on anxiety, neurochemical signaling, and cognitive functions, rather than on hormonal pathways that typically influence hair growth and loss.

Is hair loss listed as a side effect of Selank?

Published clinical studies evaluating Selank in individuals with generalized anxiety disorder and neurasthenia did not report hair loss as an observed adverse event [3]. Similarly, experimental studies examining the effects of Selank on neurotransmitters, enkephalin metabolism, and neuroplasticity did not show alopecia or changes in hair growth associated with the peptide's use [1,2].

Reviews of Selank's safety profile typically describe it as well-tolerated, highlighting the absence of many side effects often associated with traditional anxiolytics, such as excessive sedation, cognitive impairment, or dependence development [1].

Can Semax Indirectly Affect Hair Growth?

Currently, there is no evidence to suggest that Selank directly affects hormones commonly associated with hair loss, including:

• Dihydrotestosterone (DHT)
• Testosterone
• Thyroid hormones
• Estrogen
• Cortisol

However, chronic psychological stress and anxiety can contribute to some types of hair loss, particularly telogen effluvium, where a larger number of hair follicles enter the resting phase of the hair growth cycle.

Because Selank exhibits anxiolytic properties and may improve stress adaptation in some individuals [1–3], researchers suggest that curtailing excessive stress responses could theoretically support general well-being. Nevertheless, no studies have directly analyzed the effects of Selank on hair growth, hair loss, or scalp biology.

Does Selank Affect Growth Factors Related to Hair Biology?

Experimental studies have shown that Selank may affect pathways associated with neuroplasticity, including the regulation of brain-derived neurotrophic factor (BDNF) expression in the hippocampus [6]. While growth factors play an important role in many biological processes, there is currently no evidence linking Selank-induced neurotrophic changes to hair growth changes or an increased risk of hair loss.

Current Scientific Findings

Based on currently available data, Selank is not known to be a substance that causes hair loss. Neither clinical trials involving humans nor preclinical studies have identified alopecia or increased hair loss as a recognized adverse effect [1–4]. Furthermore, there is no evidence that Selank directly affects hormonal pathways commonly associated with hair loss.

Since long-term safety studies are still limited, further research is needed to fully characterize the effects of Selank in diverse populations and during prolonged use.

Can Selank Cause Insomnia?

Does Selank cause insomnia?

Insomnia means difficulty falling asleep, staying asleep, or achieving restorative rest despite adequate sleeping conditions. As Selank can affect neurochemical signaling and cognitive functions, some individuals wonder if it might disrupt sleep.

Based on the available scientific literature, insomnia has not been identified as a common side effect of Selank [1-4].

Most studies describe Selank as an anxiolytic peptide that regulates neurochemical systems associated with stress, without causing significant sedation, cognitive impairment, or intoxication [1]. Clinical trials in humans have also shown good tolerability and have not indicated insomnia as a significant adverse effect of therapy [3].

Why Do Some People Ask About Insomnia?

Some of these concerns may stem from observations that Selank has demonstrated anti-asthenic and psychostimulant effects in some clinical studies [3].

In a study involving individuals with generalized anxiety disorder and neurasthenia, Selank demonstrated an anxiolytic effect comparable to medazepam, while simultaneously improving mental energy levels and reducing fatigue [3]. These observations suggest that Selank may support alertness and decrease feelings of mental exhaustion in some individuals.

However, a psychostimulatory effect does not automatically mean that a substance causes insomnia. Current data do not indicate that Selank causes the clear central nervous system stimulation typical of classic stimulants.

Can Selank affect sleep patterns?

Because Selank appears to affect cognitive and emotional processes without causing significant sedation [1,3], individual responses may vary.

Some individuals may experience greater mental clarity or increased alertness after using Selank, particularly if anxiety-related fatigue is reduced. Theoretically, changes in perceived alertness could influence when some individuals fall asleep. However, this possibility has not been systematically studied, and no clinical trials have shown Selank to cause insomnia.

Can Selank Cause Anxiety?

Available scientific data suggest the opposite situation.

Selank was developed specifically as an anxiolytic peptide and has demonstrated anxiolytic effects in both experimental and human studies [1–4]. Clinical studies have shown improvement in anxiety symptoms in individuals with generalized anxiety disorder and neurasthenia [3].

Mechanistic studies suggest that these effects may involve several pathways, including positive allosteric modulation of GABA receptor activity, regulation of endogenous opioid peptides such as enkephalins, influence on neuroplasticity-related pathways, and modulation of stress-responsive neurochemical systems [1,2,6].

These mechanisms are generally associated with reducing anxiety, not causing it.

Can some people experience increased anxiety?

Although available research indicates Selank's anxiolytic profile, individual responses to psychoactive substances can vary.

Currently, no studies have been published showing that Selank routinely causes anxiety or panic attacks. However, because long-term data is limited and individual neurobiology varies, scientists cannot entirely rule out the possibility of unexpected subjective reactions in some individuals.

It should be emphasized that isolated anecdotal reports should not be interpreted as evidence that anxiety or insomnia are confirmed side effects of Selank.

Current Scientific Findings

Current data do not indicate that insomnia is a frequent adverse effect of Selank. Similarly, published studies consistently confirm an anxiolytic, rather than anxiety-provoking, effect [1-4]. While individual responses may vary and long-term data remain limited, neither insomnia nor anxiety exacerbation are recognized as confirmed adverse effects in the available scientific literature.

Disclaimer

This material is for educational and informational purposes only and should not be interpreted as medical advice, diagnosis, or therapeutic recommendation. Selank remains a research peptide in many countries, and a significant portion of available data comes from preclinical studies and limited human trials. Published studies suggest that Selank has a favorable tolerability profile and anxiolytic properties, however, data regarding long-term safety is still limited.

For Research Purposes Only: Selank products offered by Semax Polska are intended exclusively for laboratory and scientific research. They are not approved for human consumption, medical use, or the diagnosis, treatment, or prevention of any diseases. Additional, well-designed human studies are necessary to fully characterize the effects of Selank on sleep, anxiety, hair biology, and other long-term safety outcomes.

References

[1] Vyunova, T. V., Andreeva, L., Shevchenko, K., & Myasoedov, N. F. (2018). Peptide-Based Anxiolytics: The Molecular Aspects of Heptapeptide Selank Biological Activity. Protein and Peptide Letters, 25(10), 914–923. https://doi.org/10.2174/0929866525666180925144642

[2] Zozulya, A. A., Kost, N. V., Sokolov, O. Y., Gabaeva, M. V., Grivennikov, I. A., Andreeva, L. N., Zolotarev, Y. A., Ivanov, S. V., Andryushchenko, A. V., Myasoedov, N. F., & Smulevich, A. B. (2001). The Inhibitory Effect of Selank on Enkephalin-Degrading Enzymes as a Possible Mechanism of Its Anxiolytic Activity. Bulletin of Experimental Biology and Medicine, 131(4), 315–317. https://doi.org/10.1023/A:1017979514274

[3] Zozulia, A. A., Neznamov, G. G., Siuniakov, T. S., Kost, N. V., Gabaeva, M. V., Sokolov, O. Y., Serebriakova, E. V., Siranchieva, O. A., Andriushenko, A. V., Telesheva, E. S., Siuniakov, S. A., Smulevich, A. B., Myasoedov, N. F., & Seredenin, S. B. (2008). Efficacy and Possible Mechanisms of Action of a New Peptide Anxiolytic Selank in the Therapy of Generalized Anxiety Disorders and Neurasthenia. Journal of Neurology and Psychiatry named after S.S. Korsakov, 108(4), 38–48. https://pubmed.ncbi.nlm.nih.gov/18454096/

[4] Kost, N. V., Sokolov, O. Y., Zozulya, S. A., & Myasoedov, N. F. (2025). Combined Action of Benzodiazepine Tranquilizers and Peptide Anxiolytic Selank in BALB/c Mice. Neurochemical Journal, 19, 743–748. https://doi.org/10.1134/S1819712425700783

[5] National Center for Biotechnology Information. (2026). PubChem Compound Summary for CID 11765600, Selank. National Library of Medicine. https://pubchem.ncbi.nlm.nih.gov/compound/Selank

[6] Levitskaya, N. G., Andreeva, L. A., Mezentseva, M. V., Shapoval, I. M., Podchernyaeva, R. Y., Shcherbenko, V. E., Potapova, L. A., Russu, L. I., Ershov, F. I., & Myasoedov, N. F. (2010). Intranasal Administration of the Peptide Selank Regulates BDNF Expression in Rat Hippocampus In Vivo. Doklady Biological Sciences, 431, 79–82. Available from: https://www.researchgate.net/profile/Natalia-Levitskaya/publication/23306196_Intranasal_administration_of_the_peptide_Selank_regulates_BDNF_expression_in_the_rat_hippocampus_in_vivo