Semax and Selank: Nootropic Peptides - Evidence, Dosage, Legal Status in the US

Key takeaways

• Semax and Selank are seven-amino-acid peptides developed in Russia and registered there as nasal drops: Semax, built from a fragment of the stress hormone ACTH, for stroke and other neurological disease; Selank, built from the immune peptide tuftsin, for mild anxiety. FDA has never approved either.
• The human evidence is small, mostly in Russian and hard to check: non-blinded stroke studies of Semax, small trials of Selank against benzodiazepines in anxiety, and brain-scan studies in a few dozen healthy volunteers. We found no placebo-controlled trial of either for focus or memory in healthy people.
• The studied doses (Semax 6 to 18 mg a day in stroke patients; Selank 2.7 mg a day in an anxiety trial) were of Russian pharmaceutical products. Seller charts mostly quote smaller amounts for sprays and vials whose content nobody verifies.
• The Russian reports describe both as well tolerated, but they come largely from the developers' institutions, and FDA flagged both for immune-reaction risk and missing human safety data.
• Neither can be legally prescribed or compounded in the US in October 2026. FDA's advisory committee recommended Semax 8-5-1 in July 2026, but no rule has followed; Selank was never put to the committee and sits in no FDA category.

Semax and Selank at a glance

Also called

Semax (Met-Glu-His-Phe-Pro-Gly-Pro; an ACTH(4-10) analog), Selank (Thr-Lys-Pro-Arg-Pro-Gly-Pro; selank acetate; TP-7), N-acetyl semax amidate (a modified variant with no human study)

Class

Synthetic heptapeptides developed in Russia: Semax is built from a fragment of adrenocorticotropic hormone (ACTH), Selank from the immune peptide tuftsin; both end in Pro-Gly-Pro

Route

Nasal drops in Russia, where both are registered; online products are nasal sprays and injectable vials; no US-approved route

FDA status

Neither is FDA-approved. Semax left FDA's Category 2 list on April 15, 2026 when its nomination was withdrawn, and FDA's advisory committee voted 8-5-1 in July 2026 to recommend it for compounding; no rule has been issued. Selank is listed by FDA as previously in Category 2 with its nomination withdrawn, sits in no FDA category and has never gone to the committee.

FDA Category 2 (compounding restricted)

No

Available by prescription (US)

No: no US pharmacy may compound either peptide, and no approved product exists

Best-studied use

Semax: recovery after ischemic stroke in small, non-blinded Russian studies. Selank: generalized anxiety disorder and neurasthenia in small Russian trials against benzodiazepines

Typical monthly cost (telehealth, 2026)

No legal US product exists to price; research vials are unapproved drugs and we do not list their prices

"Nootropic peptides" usually means two molecules, Semax and Selank. Both were developed in Russia, both are sold there as nasal drops, and both are sold online in the US as research chemicals for focus, memory and calm. This page covers what they are, what the human studies found, the doses that were studied, the risks and the legal status as of October 2026. If you are choosing between them, our Semax versus Selank comparison answers that directly, and our guide to peptides for cognitive function ranks everything that has been tested for memory and thinking, including the peptides with real trials behind them. For the basics of what a peptide is, start with what are peptides.

What Semax and Selank are and how they work

Both are heptapeptides, chains of seven amino acids, and both end in the same three: proline, glycine, proline.

Semax (Met-Glu-His-Phe-Pro-Gly-Pro) borrows its first four amino acids from adrenocorticotropic hormone (ACTH), the pituitary hormone that signals the adrenal glands. Its developers describe it as an analog of the ACTH(4-10) fragment and report that, given into the nose at 0.015 to 0.05 mg per kilogram, it improved memory and attention in animals and people for 20 to 24 hours (Ashmarin 1997). The mechanism most often cited is brain-derived neurotrophic factor (BDNF), a protein that supports the survival and adaptability of neurons. In rats, a single intranasal dose of 50 mcg/kg raised BDNF protein in the hippocampus 1.4-fold and activation of its receptor, trkB, 1.6-fold, and the treated rats learned an avoidance task faster (Dolotov 2006). In Russia, Semax is used mainly for stroke and other neurological disease (Renke 2026).

Selank (Thr-Lys-Pro-Arg-Pro-Gly-Pro) is tuftsin, a four-amino-acid peptide with immune activity, extended by the same Pro-Gly-Pro tail. In Russia it is registered for mild anxiety (Renke 2026). Two mechanisms are proposed. In human serum in a test tube, both Selank and Semax block the enzymes that break down enkephalins, the body's own opioid peptides (Kost 2001), and in a Russian anxiety trial, patients with generalized anxiety had unusually fast enkephalin breakdown that slowed during Selank treatment (Zozulia 2008). Selank is also described as acting on GABA signaling, the system benzodiazepines act on, which is why a US clinical pharmacology review grouped it with GABA-acting sedatives and called it a poorly studied Russian drug that is being sold to American consumers as a dietary supplement (Doyno 2021).

Both are given through the nose on the theory that this route carries peptides toward the brain. We found no English-language study measuring how much of either reaches the human brain. The honest summary of the mechanism is plausible effects in rats and test tubes; the question that matters is whether either peptide changes anything a person can feel or measure.

What the evidence actually shows

Almost all clinical work on both peptides was done in Russia, much of it by groups connected to their developers, and published in Russian journals with short English abstracts. We read every PubMed abstract cited below and, where it was available, the Russian full text. FDA's reviewers hit the same wall: at the July 2026 advisory committee they said the literature, much of it in Russian, often lacked the routes of administration, doses and study details needed to verify its claims (Hyman Phelps 2026).

Semax and Selank claims, graded by the evidence behind them

Claim	Grade	What the evidence shows	Sources
Semax speeds recovery after ischemic stroke	C	In 30 patients with acute hemispheric stroke, adding Semax at 12 mg a day (moderate strokes) or 18 mg a day (severe) for 5 to 10 days was reported to speed recovery of general and motor deficits compared with 80 patients on usual care. In 110 patients in stroke rehabilitation, two 10-day courses of 6 mg a day were reported to raise plasma BDNF and improve the Barthel index of daily function. Neither study was blinded or placebo-controlled.	Gusev 1997; Gusev 2018
Semax improves memory, attention or focus in healthy people	C	The developers report better memory and attention in healthy men working under extreme conditions, with no numbers in the abstract. The only indexed healthy-volunteer study gave one nasal dose of 1% Semax to 14 adults and placebo to 10 and measured brain-network activity on functional MRI, not memory or attention.	Ashmarin 1997; Lebedeva 2018
Semax raises BDNF, a brain growth factor	C	In rats, one 50 mcg/kg dose raised hippocampal BDNF 1.4-fold. In stroke patients, plasma BDNF rose with Semax in a non-blinded comparison. Whether this changes thinking in a healthy brain has not been tested.	Dolotov 2006; Gusev 2018
Selank relieves anxiety	B	In 62 patients with generalized anxiety disorder or neurasthenia, Selank (30 patients) and the benzodiazepine medazepam (32) reduced anxiety to a similar degree, and Selank was reported to have added anti-fatigue and stimulant effects. No placebo group is described.	Zozulia 2008
Selank reduces benzodiazepine side effects	B	70 patients with anxiety disorders were randomized to phenazepam 2 mg a day alone or with Selank 2.7 mg a day for 14 days. The combination was reported to work faster and to cause less sedation and fewer attention and memory complaints. No placebo or blinding is described.	Medvedev 2015
Selank sharpens focus or memory	C	Cognition was a secondary measure at most: Stroop and verbal-fluency tests in a benzodiazepine add-on trial, and investigators' descriptions of stimulant effects. No trial used a cognitive primary outcome.	Zozulia 2008; Medvedev 2015
Both act on the brain's opioid and GABA systems	D	In human serum in a test tube, Semax and Selank inhibited enkephalin-degrading enzymes at 10 and 20 micromolar. Selank's GABA effect comes from rat-brain and cell studies; a US review classes it with GABA-acting sedatives.	Kost 2001; Doyno 2021
Safe for regular long-term use	D	No long-term safety study in English. The developers report no negative effects in their experience; FDA cited a risk of immune reactions from aggregation and peptide impurities and said it lacked human safety information for both.	Ashmarin 1997; FDA Category 2
Treats ADHD, depression or dementia	D	We found no human trial of either peptide in ADHD, depression or dementia, and no registered trial of either on ClinicalTrials.gov.	Our PubMed and ClinicalTrials.gov searches, October 10, 2026

Three things stand out.

No one has tested the marketed use. Semax's human data are about stroke; Selank's are about clinical anxiety. The claim on most product pages, sharper focus and memory in a healthy adult, rests on a developer summary without numbers and on brain scans taken minutes after a single dose.

The designs cannot separate the drug from expectation. None of the trials we could read had a placebo group with blinding. In the stroke studies, patients who received Semax were compared with patients who did not, which is how a real effect and a hopeful assessor look the same.

The products studied are not the products sold. The Russian trials used registered pharmaceutical nasal drops. The sprays and vials sold online are made by unknown manufacturers, and a Belgian medicines-control laboratory found Semax and Selank in seized preparations of unknown origin and noted how freely such products are sold as powders for injection and as nasal sprays (Vanhee 2020).

What you are promised versus what is documented

Product pages for Semax and Selank tend to promise the same list: laser focus, better memory, faster learning, calm without sedation, better mood, protection against brain aging, a "BDNF boost," and help with ADHD and brain fog. The evidence sorts them into three bins.

• Documented in people, weakly: Selank relieved clinical anxiety about as much as a benzodiazepine in small trials without a placebo; Semax added to stroke care was associated with better recovery in non-blinded studies; both change brain-scan measures after one dose.
• Plausible but untested in people: better focus or memory in healthy adults; neuroprotection through BDNF; anxiety relief without sedation or dependence over months.
• Not supported: treatment of ADHD, depression or dementia; long-term safety; and any claim that an online spray or vial delivers what the Russian studies used.

Semax and Selank versus the realistic alternatives

The comparison is uncomfortable for the peptides. Anxiety and ADHD have treatments that were tested in large trials and that a clinician can prescribe and adjust. The one peptide with a randomized cognitive signal in older adults is tesamorelin, and even that rests on a single trial, as our cognitive-function guide explains. If sleep is part of the problem, our sleep guide and DSIP profile cover the peptides sold for that, with the same caution.

Dosage: what was studied versus what sellers circulate

And what circulates online, as claims:

Two cautions apply to every row. The Russian doses were measured in a labeled pharmaceutical product, so 6 mg meant 6 mg; a research spray's label means whatever its seller wrote. And a microgram figure for a nasal spray depends on the concentration and the volume of each spray, neither of which anyone checks.

Why there is no reconstitution example

Our compound pages normally show how a prescribed vial is mixed and drawn up. We do not do that here, because there is no legal Semax or Selank product in the United States to reconstitute, no pharmacy label to check the arithmetic against, and FDA's 2026 warning letters treated reconstitution help bundled with research vials as evidence that they were drugs sold for human use, as our legal tracker records. The reconstitution calculator is built for medications a pharmacy has dispensed with a labeled concentration; neither of these has one.

Side effects and who should not use them

The Russian literature describes both peptides as well tolerated. Semax's developers wrote that it produced no negative effects in their experience (Ashmarin 1997), and a 2026 review lists mild nasal irritation and transient agitation as the occasional side effects reported for Semax and calls Selank non-sedating and non-addictive (Renke 2026). Read those statements for what they are: summaries by or of the developers, from small, short studies, without systematic adverse-event reporting in English.

FDA's own assessment is the counterweight. When it placed both in Category 2, it said compounded versions may risk immune reactions because peptides can aggregate and carry synthesis impurities, and that it lacked human safety information for the routes proposed (FDA Category 2). Repeated exposure to an immunogenic product is exactly the situation a months-long "cycle" creates.

Then there are the risks that come from the product rather than the peptide: unknown content and dose, possible contamination, and, for anything injected, no sterility assurance. Our peptide side effects guide covers these in general.

Do not use either, or do so only with a clinician who knows, if you:

• are pregnant, trying to conceive or breastfeeding (no data);
• are under 18 (no data we could verify in English);
• take benzodiazepines, sleep medicines, alcohol regularly or other sedatives (Selank is described as GABA-acting, and its main trial combined it with a benzodiazepine under supervision);
• have a diagnosed anxiety disorder, ADHD, depression, a seizure disorder or a memory problem being treated: do not replace or stop that treatment for a research peptide;
• have had a stroke or have stroke symptoms now: stroke is an emergency, and the Russian studies added Semax to standard care, never used it instead.

Legal status in the United States

Neither peptide can be legally prescribed and dispensed in the United States in October 2026, and their paths differ.

• Semax. FDA placed it in Category 2, the list of nominated substances that may present significant safety risks, and took it off that list on April 15, 2026 after its nomination was withdrawn. On the second day of its July 23-24, 2026 meeting, FDA's Pharmacy Compounding Advisory Committee voted 8 in favor, 5 against with 1 abstention to recommend adding Semax to the list of substances 503A pharmacies may use, for the uses evaluated: cerebral ischemia, migraine and trigeminal neuralgia (Kelley Drye 2026). FDA's staff had recommended against all of the peptides on the agenda (Kelley Drye 2026), and the committee's acting chair flagged that the name is easy to confuse with semaxanib, an unrelated compound (Hyman Phelps 2026). The vote is advice. FDA must publish a proposed rule, take comments and finalize it before any pharmacy may compound Semax, and as of our last check in October 2026 no proposed rule had appeared.
• Selank. FDA lists selank acetate among the substances that were in Category 2 until their nominators withdrew them, with the same immunogenicity concern and a note that it lacks safety information on human use (FDA Category 2). In FDA's list updated May 14, 2026, Selank appears in none of the three categories (FDA categories 2026), it is not on the list of substances pharmacies may use, and it was not on the advisory committee's agenda in 2024 or July 2026 or on the list due for review by February 2027. Nothing pending would make it compoundable.
• What that means for sellers and buyers. Possessing either peptide is not a crime. Selling either for human use is selling an unapproved drug, whether the label says "research use only" or "dietary supplement." The legal tracker records the 2026 warning letters and will record any rule on Semax.

Cost and how to get it prescribed

There is no legal product to price, and we do not list prices for research vials or sprays. What you can legitimately pay for is a clinician's evaluation of the problem you hoped a nootropic would fix. If the issue is anxiety, attention, memory or fatigue, a primary-care clinician, psychiatrist or neurologist can look for treatable causes and prescribe approved treatment; our peptide therapy cost guide shows what telehealth visits and labs typically cost in 2026, and our page on what telehealth can prescribe explains why no legitimate service will ship you Semax or Selank. For the end-to-end process of evaluation, prescription and monitoring for the peptides that are legal, see the complete guide to peptide therapy.

Women, older adults and pregnancy

Women were well represented in the Semax stroke-rehabilitation study (67 of 110 patients) and in the healthy-volunteer brain-scan study (13 of 24) (Gusev 2018) (Lebedeva 2018), and no sex-specific effect was reported in the abstracts. Older adults appear only as stroke patients; no study has tested either peptide for age-related memory decline or dementia. There are no data in pregnancy or breastfeeding, and neither should be used then.

Bottom line

Semax and Selank are real drugs in Russia, with real if small clinical literatures: Semax as an add-on after stroke, Selank as an anxiolytic that matched benzodiazepines in short trials. What they are not is proven nootropics. No controlled trial has shown that either sharpens focus or memory in a healthy person, the trials that exist were not blinded, much of the evidence is untranslated and developer-linked, and FDA's reviewers could not verify the details. In the United States, neither can be legally prescribed in October 2026; Semax has a committee recommendation and no rule, and Selank has nothing pending. If you want better focus or less anxiety, the treatments with evidence are a clinician away, and the peptides with actual cognitive trials are ranked in our cognitive-function guide.

Frequently asked questions

+−What is a nootropic peptide?

A nootropic is anything sold to improve thinking: focus, memory, learning or mental energy. In the peptide market the term almost always means Semax and Selank, two seven-amino-acid peptides developed in Russia and registered there as nasal drops, Semax for stroke and other neurological disease and Selank for mild anxiety. The label is a marketing category, not a drug class. Neither peptide has a placebo-controlled trial showing better focus or memory in healthy people, and neither is approved in the United States.

+−Is Semax legal in the US?

It is not FDA-approved, and as of October 2026 no licensed US pharmacy may compound it. FDA took Semax off its Category 2 safety-risk list on April 15, 2026 after the nomination was withdrawn, and FDA's advisory committee voted 8 to 5 with one abstention in July 2026 to recommend adding it to the list of substances pharmacies may use, over the objection of FDA's reviewers. A recommendation is not a rule: FDA has to propose and finalize one, and none had appeared by early October 2026. Possessing it is not a crime; selling it for human use is.

+−Is Selank legal in the US?

No legal source exists. Selank is not FDA-approved, it is not on the list of substances US pharmacies may compound, and FDA lists it among peptides that were in Category 2 until their nominations were withdrawn. Unlike Semax, it was not reviewed by FDA's advisory committee in 2024 or July 2026 and is not on the list FDA plans to bring to the committee by February 2027, so nothing pending would change its status.

+−What is Semax used for?

In Russia, mainly as an add-on treatment after ischemic stroke and in other neurological conditions, given as nasal drops. The supporting studies are Russian and small: 30 stroke patients compared with 80 on usual care in 1997, and 110 patients in stroke rehabilitation in 2018, neither blinded or placebo-controlled. Online it is sold for focus, memory and 'brain fog', uses that have not been tested in a controlled trial.

+−Is there a peptide for anxiety?

Selank is the peptide sold for anxiety. In small Russian trials it relieved anxiety in patients with generalized anxiety disorder about as much as the benzodiazepines it was compared with, without a placebo group, and it cannot be legally obtained in the US. Anxiety disorders have FDA-approved medicines and psychotherapy with large randomized trials behind them; a clinician can match one to you. Do not stop a prescribed anxiety medicine to try a research peptide.

+−Can a doctor prescribe Semax or Selank?

A US clinician can write anything on a prescription pad, but no licensed pharmacy may fill it: neither peptide is FDA-approved, neither is a component of an approved drug, neither has a USP monograph, and neither is on FDA's list of bulk substances for compounding. A clinic that ships you Semax or Selank in October 2026 is supplying a research product, whatever paperwork comes with it.

+−What dose of Semax or Selank was studied?

In Russian stroke studies, Semax was given at 12 to 18 mg a day for 5 to 10 days in the acute phase and at 6 mg a day in two 10-day courses during rehabilitation; the developers summarized cognitive effects at 0.015 to 0.05 mg per kilogram intranasally. In an anxiety trial, Selank was given at 2.7 mg a day for 14 days alongside a benzodiazepine. These are studied doses of Russian pharmaceutical products, not a protocol, and they say nothing about what is in an online spray or vial.

+−Are nootropic peptides safe?

Nobody has shown that they are. The Russian reports describe Semax and Selank as well tolerated, with occasional nasal irritation, but those reports come largely from the developers' institutions, and there are no long-term safety data in English. FDA flagged both for possible immune reactions to impurities and aggregated peptide and said it lacked human safety information. Online products add their own risk: their content, purity and sterility are not verified by anyone.

Sources

1. ReviewAshmarin (Asmarin) IP et al. A nootropic adrenocorticotropin analog 4-10, Semax (15 years experience in its design and study). Zh Vyssh Nerv Deiat Im I P Pavlova 1997;47:420-30. In Russian. (1997)
2. StudyGusev EI et al. Effectiveness of Semax in acute period of hemispheric ischemic stroke (a clinical and electrophysiological study). Zh Nevrol Psikhiatr Im S S Korsakova 1997;97:26-34. In Russian. (1997)
3. StudyGusev EI et al. The efficacy of Semax in the treatment of patients at different stages of ischemic stroke. Zh Nevrol Psikhiatr Im S S Korsakova 2018;118:61-68. In Russian. (2018)
4. StudyLebedeva IS et al. Effects of Semax on the default mode network of the brain. Bull Exp Biol Med 2018;165:653-656. (2018)
5. StudyDolotov OV et al. Semax, an analog of ACTH(4-10) with cognitive effects, regulates BDNF and trkB expression in the rat hippocampus. Brain Res 2006;1117:54-60. (2006)
6. StudyZozulia 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;108:38-48. In Russian. (2008)
7. StudyMedvedev VE et al. Optimization of the treatment of anxiety disorders with Selank. Zh Nevrol Psikhiatr Im S S Korsakova 2015;115:33-40. In Russian. (2015)
8. StudyKost NV et al. Semax and Selank inhibit the enkephalin-degrading enzymes from human serum. Bioorg Khim 2001;27:180-3. In Russian. (2001)
9. ReviewDoyno CR, White CM. 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. (2021)
10. StudyVanhee 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;12:371-381. (2020)
11. ReviewRenke G, Chinellato L. Therapeutic peptides in aesthetic, metabolic and endocrine conditions: effects, safety, clinical applications, and future perspectives. Int J Mol Sci 2026. (2026)
12. RegulatoryFDA. Certain bulk drug substances for use in compounding may present significant safety risks: Category 2 list and bulk drug substances nominated but withdrawn (Semax, selank acetate). Content current as of April 22, 2026. (2026)
13. RegulatoryFDA. Bulk drug substances nominated for use in compounding under section 503A: Category 1, 2 and 3 lists and updates (updated May 14, 2026). (2026)
14. NewsSnow CD, Palmer KL, Bass M. PCAC adds two more bulk drug substances for the 503A list (epitalon, Semax; emideltide rejected). FDA Law Blog, Hyman Phelps & McNamara, July 28, 2026. (2026)
15. NewsKelley Drye. FDA advisory committee recommends several peptides for compounding despite staff opposition: what stakeholders need to know (uses evaluated for Semax: cerebral ischemia, migraine and trigeminal neuralgia). July 30, 2026. (2026)