Selank and Semax: Russia's Cognitive Peptides Examined

Selank and Semax are short synthetic peptides developed in Russia and approved there as medicines: Selank for anxiety, and Semax for stroke recovery and certain cognitive disorders. Both are typically given as nasal sprays and act on brain signaling systems, including brain-derived neurotrophic factor (BDNF). Neither is FDA-approved, and the human evidence behind them is small, mostly Russian-language and largely unreplicated elsewhere.

Where Selank and Semax Come From

Both peptides came out of Russian research institutes in the late Soviet and post-Soviet era, and both were built by modifying a naturally occurring peptide fragment and adding a short "Pro-Gly-Pro" tail to slow breakdown in the body.

• Selank is a seven-amino-acid analog of tuftsin, a small peptide naturally involved in immune function. It was developed as an anti-anxiety agent.
• Semax is a seven-amino-acid analog of a fragment of adrenocorticotropic hormone, ACTH(4-10). Importantly, it keeps some of that fragment's brain effects but lacks ACTH's hormonal activity on the adrenal glands.

Because they were developed and approved within the Russian regulatory system, most of the clinical literature is published in Russian journals. That does not make it wrong, but it does mean much of it has not been independently reproduced or evaluated by US or European regulators.

How They Are Thought to Work

Selank

Based on the available research, Selank appears to influence several systems at once:

• It modulates GABA signaling, the same calming system targeted by benzodiazepines, but without binding directly to GABA receptors
• It affects the enkephalin system (the body's own opioid-like peptides) and serotonin signaling
• It has been reported to increase BDNF expression in the hippocampus of rats
• As a tuftsin relative, it also shows immune-modulating effects on cytokines

Semax

Semax is described primarily as a neurotrophic and neuroprotective agent:

• In rat studies, it increases BDNF and its receptor (TrkB) in brain tissue
• It modulates dopamine and serotonin systems, which may relate to attention and motivation
• In models of stroke, it appears to reduce injury from excitotoxicity, the cascade that damages neurons after blood flow is interrupted

Both are generally given intranasally. The proposed rationale is that nasal delivery allows some of the peptide to reach the brain through olfactory and trigeminal nerve pathways, bypassing much of the breakdown that would occur in the bloodstream.

What the Evidence Shows

It helps to sort the evidence honestly.

What has been studied in humans:

• A Russian clinical trial in generalized anxiety disorder reported that Selank reduced anxiety to a degree comparable with a benzodiazepine (medazepam), without the cognitive dulling.
• A Russian multicenter trial reported improved functional recovery when Semax was added to standard care after acute ischemic stroke.
• A small study in healthy adults reported improvements in attention and working memory measures with Semax.

What is mostly animal or mechanistic:

• BDNF increases, neuroprotection in ischemia models, and anti-stress effects largely come from rodent studies.

What is unknown:

• Long-term safety with repeated use
• Effects in healthy people using them for "optimization" rather than illness
• Interactions with antidepressants, stimulants, anti-anxiety medications or other psychiatric drugs
• Whether the Russian results hold up in larger, independent, placebo-controlled trials

FDA Status of Selank and Semax

Neither peptide is FDA-approved for any use in the United States. Their compounding status has been in flux:

• In 2023, FDA flagged both, along with many other peptides, as raising potential safety concerns for compounding (the so-called "Category 2" list), citing limited safety data and concerns about immune reactions and impurities.
• In April 2026, Semax was among 12 peptides FDA moved off that list so its Pharmacy Compounding Advisory Committee (PCAC) could review it.
• In July 2026, the PCAC narrowly voted to recommend adding Semax to the list of substances that may be compounded. That vote is advisory. FDA rulemaking is still pending, and compounding is not yet authorized.
• Selank was not among the peptides the committee voted on in July 2026. It is not FDA-approved, and there is currently no authorized pathway for US pharmacies to compound it.

Because this landscape has changed several times since 2023, check current FDA guidance before relying on any status statement, including this one. For the broader picture, see The Future of Peptide Regulation in the United States.

Who Might Be Interested, and What to Do First

People usually ask about Selank and Semax for one of three reasons: persistent anxiety, "brain fog," or a desire for sharper focus at work. Each of those deserves a medical look before a peptide conversation:

• Anxiety: thyroid overactivity, excess caffeine, alcohol, stimulant medications, poor sleep and untreated depression are common contributors. Cognitive behavioral therapy and established medications have strong evidence.
• Brain fog: low B12, iron deficiency, hypothyroidism, sleep apnea, perimenopause, low testosterone, blood sugar swings and medications with anticholinergic effects are frequent and treatable causes.
• Focus and performance: sleep, aerobic fitness and alcohol reduction have far more evidence for cognitive performance than any peptide.

In my practice, I start with labs and a careful history. Only when the foundation is addressed, and only with an honest discussion of the evidence and regulatory status, does it make sense to talk about investigational compounds. Any such discussion is individualized; I do not use generic dosing protocols. You can read compound summaries for Selank and Semax in our peptide library, and compare them with another Eastern European neuropeptide in Cerebrolysin: The Neurotrophic Peptide Complex for Brain Health.

The Bottom Line

Selank and Semax are interesting molecules with a real, if limited, clinical history in Russia. Their mechanisms, especially effects on BDNF and calming neurotransmitter systems, make biological sense. But the evidence base is small, regional and not independently confirmed, long-term safety is unknown, and US regulatory status remains unsettled. At Laeeq M.D., they are a topic for careful discussion, not a starting point.

Sources

• US Food and Drug Administration. "Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks." FDA, updated 2026. https://www.fda.gov/drugs/human-drug-compounding/certain-bulk-drug-substances-use-compounding-may-present-significant-safety-risks
• "FDA Panel Backs 6 Peptides for Compounding." AJMC, July 31, 2026. https://ajmc.com/view/fda-panel-backs-6-peptides-for-compounding

Book a Consultation

If anxiety, focus or brain fog is affecting your life, start with a thorough evaluation. You can book a consultation with Dr. Laeeq for a 60-minute visit, virtual or in person in Falls Church, VA, to look for treatable causes and talk through every option honestly.

This article is for educational purposes and is not medical advice. Discuss any treatment with a licensed physician who knows your history.