Semax
Grey marketNot approved for human use in the US, and sold anyway.
Two Russian studies reported faster recovery after ischemic stroke when semax was added to standard care, but their abstracts describe no randomization and give no effect sizes. No controlled human research on focus or memory was sourced. Semax is not FDA-approved. FDA found too little safety information to characterize it and raised a possible bleeding risk.
Add to Bio HackChecked 2026-11-09
- Status
- Not FDA-approved for any use in the US. Registered as a drug in Russia, as nasal drops. FDA removed semax from compounding category 2 on April 22, 2026, after its nominations were withdrawn, and did not place it in category 1. Under a draft, interim HHS policy announced October 30, 2026, HHS does not intend to take enforcement action against state-licensed pharmacies, federal facilities or licensed physicians compounding with semax while the 503A bulks list is developed through rulemaking.
- Also called
- semax acetate, ACTH 4-10 analog, ACTH(4-10) Pro-Gly-Pro, Met-Glu-His-Phe-Pro-Gly-Pro, heptapeptide semax
- Taken for
- focus, memory, cognition, stroke recovery, brain health, anxiety, mood, ADHD
Strong several reviews agree · Moderate one review or consistent trials · Limited one or a few small studies · Untested no study in people, listed with what it rests on
Shown to help1
Reported risks4
- LimitedFDA states it has no or limited safety information on semax. It removed semax from category 2 in April 2026 after nominations were withdrawn.How often is not known
- LimitedFDA states there is too little clinical information to describe semax's safety profile, raises bleeding and immune reaction concerns, and weighed against allowing it for compounding.How often is not known
- LimitedHHS states it does not intend to take enforcement action against licensed compounding with semax for now. Compounded drugs are not FDA-approved.How often is not known
- LimitedCase reports: FDA's database held one report, eye pain and burning after semax nasal drops, with hospitalization. One voluntary report cannot show cause.How often is not known
What people take it for, and what was found
Shown to help1
Recovery after ischemic stroke
Limited evidence: two Russian studies reported faster recovery after ischemic stroke with semax added to standard care, without effect sizes, randomization or blinding described.
The numbers and sources
- Effect
- In the acute period of hemispheric ischemic stroke, adding semax to intensive therapy was reported to increase the rate of recovery of general and focal deficits, especially motor deficits, compared with patients on conventional therapy [1]. After ischemic stroke, patients who received semax during rehabilitation had higher blood BDNF levels throughout the study, and faster improvement and a better final score on the Barthel index of daily living activities, than those who did not [2]. Neither abstract gives effect sizes.
- Population
- 30 patients on semax and 80 controls with acute hemispheric ischemic stroke [1]. 110 patients after ischemic stroke, mean age 58, split into semax and no semax subgroups within early and late rehabilitation groups, with two 10-day courses [2].
- Sources
- [1], [2]
- Caveats
- Both studies were published in Russian with English abstracts, and neither abstract describes randomization or blinding. Semax was given alongside standard therapy. FDA did not evaluate the Russian-language stroke studies because full English versions were not available, and found that professional society stroke guidelines do not discuss semax [3].
Mixed results1
Focus, memory and mental performance
Limited evidence: one placebo-controlled study found a nasal dose changed resting brain networks on fMRI in healthy adults. No memory or attention results were sourced.
The numbers and sources
- Effect
- In 24 healthy volunteers, a single nasal dose of semax enlarged the medial frontal part of the brain's default mode network on resting-state fMRI, against placebo [9]. A 2007 hypothesis paper states that semax has been found to stimulate memory and attention in rodents and humans after nasal use [10]. FDA found that the human studies of its nootropic effects were in healthy adults or written in Russian, and did not evaluate the Russian-language reports [3].
- Population
- 24 healthy adults, mean age 43.9, 14 on semax and 10 on placebo [9].
- Sources
- [9], [10], [3]
- Caveats
- The fMRI study measured brain activity at rest, not focus, memory or performance [9]. The human memory and attention reports could not be read in full, and the hypothesis paper gives no figures [10].
Claimed, not studied in people2
Anxiety and mood
Not studied in people. In rats under chronic stress, semax reversed loss of interest in sweetened water, a depression-like sign, and restored hippocampal BDNF.
No study in people. This rests on animal studies, how it acts in the body.
The numbers and sources
- Effect
- In male rats under chronic unpredictable stress, daily semax injections reversed or reduced stress-induced anhedonia, the stress-related slowing of weight gain, adrenal enlargement and the fall in hippocampal BDNF. It did not change immobility in the forced swim test [11]. FDA's review notes antidepressant-like and anxiety-reducing effects in rodents [3]. In 52 healthy adults, a single dose of semax or the related peptide selank changed resting connectivity between the right amygdala and temporal cortex on fMRI, against placebo [12].
- Population
- Male Sprague-Dawley rats [11]. Rodent studies reviewed by FDA [3]. 52 healthy adults [12].
- Sources
- [11], [3], [12]
- Caveats
- Rodent models of stress do not show what happens to anxiety or mood in people. The fMRI study measured brain connectivity, not symptoms [12]. FDA lists a meeting abstract of semax given with therapy to 120 children with depression, with no full results available [3].
ADHD
Not studied in people. A Russian expert council lists semax as an ADHD add-on with a limited evidence base, and animal work shows dopamine and BDNF effects.
No study in people. This rests on documented traditional use, animal studies, how it acts in the body.
The numbers and sources
- Effect
- In 2026 an expert council of Russian pediatric neurologists placed semax in its group of add-on ADHD medicines with a limited evidence base, used in Russian practice, below a group backed by a double-blind trial. It stated that add-on therapy is not a substitute for atomoxetine in eligible patients [13]. A 2007 hypothesis paper proposed semax for ADHD because in animal studies it increased the effect of stimulants on brain dopamine release and raised brain BDNF [10].
- Population
- Clinical practice in Russia, as assessed by an expert council [13]. Animal studies, reviewed [10].
- Sources
- [13], [10]
- Caveats
- A consensus statement and a hypothesis paper, not trial results. No trial of semax in ADHD was located.
Risks
Reported risks4
FDA compounding category 2 listing
FDA states it has no or limited safety information on semax. It removed semax from category 2 in April 2026 after nominations were withdrawn.
The numbers and sources
- How common
- How often is not known: the sources give no rate.
- Effect
- FDA states that it has no, or limited, safety-related information on semax for the proposed routes of administration. Semax appears on FDA's list of substances previously in category 2 whose nominations were withdrawn by the nominators [4]. FDA removed semax from category 2 on April 22, 2026, because the nominations were withdrawn, and semax does not appear in category 1 of that update [5].
- Population
- Compounded drug products in the US [4][5].
- Sources
- [4], [5]
- Caveats
- A regulatory assessment of compounded products, not a study of harm.
FDA's 2026 safety review
FDA states there is too little clinical information to describe semax's safety profile, raises bleeding and immune reaction concerns, and weighed against allowing it for compounding.
The numbers and sources
- How common
- How often is not known: the sources give no rate.
- Effect
- FDA's briefing document for its Pharmacy Compounding Advisory Committee concluded that there is insufficient clinical information to characterize the safety profile of semax. FDA found no human pharmacokinetic studies by any route and no safety data for injection. The published human record, all by the nasal route, covered about 33 to 47 healthy adults, 69 adults with medical conditions and 451 children, and most of those reports did not discuss adverse events. One report described possible anti-clotting properties, which FDA said raises concern about bleeding, particularly in people at risk of bleeding or taking other medicines that increase it. FDA described semax as not well characterized, raised concern about immune reactions to injected and nasal spray forms, and concluded that the balance of criteria weighs against placing semax on the list of substances allowed for pharmacy compounding [3].
- Population
- FDA review of published literature, adverse event databases and the nominations [3].
- Sources
- [3]
- Caveats
- The advisory committee considered semax on July 24, 2026 [5], and its votes are advice to FDA, which makes the final determination [3]. Trade press reported that the committee voted 8 to 5, with 1 abstention, for semax in both acetate and free base forms [6]. No FDA-published tally was located for this page.
HHS interim compounding policy
HHS states it does not intend to take enforcement action against licensed compounding with semax for now. Compounded drugs are not FDA-approved.
The numbers and sources
- How common
- How often is not known: the sources give no rate.
- Effect
- In a notice of a draft, interim policy, HHS states that it does not intend to take enforcement action against a State-licensed pharmacy, Federal facility or licensed physician compounding with a peptide listed in the policy's Appendix A while the 503A bulks list is developed through rulemaking [7]. Semax is on that list [8]. The notice states: "Compounded drugs are not FDA-approved, which means FDA does not review their safety, effectiveness, or quality before they are marketed." HHS may revisit the policy "if, among other things, a safety signal or product quality issue arises" with a compounded product it covers, and the policy is "not binding on HHS or the public" [7].
- Population
- Compounded drug products in the US [7][8].
- Sources
- [7], [8]
- Caveats
- A statement of enforcement intent, not an FDA approval and not a study of harm. FDA's future rulemaking may or may not add semax to the 503A bulks list [7].
Reported adverse events
Case reports: FDA's database held one report, eye pain and burning after semax nasal drops, with hospitalization. One voluntary report cannot show cause.
The numbers and sources
- How common
- How often is not known: the sources give no rate.
- Effect
- FDA's adverse event database held one report for semax through December 3, 2025. A consumer reported eye pain and burning after using semax nasal drops in May 2024, with hospitalization, and the eye pain had not resolved when it was reported a year later. FDA found no case reports of adverse events in the published literature [3].
- Population
- Voluntary reports to FDA [3].
- Sources
- [3]
- Caveats
- A single voluntary report cannot establish cause or a rate. Reporting is voluntary and incomplete [3].
Possible, not studied in people1
Abuse potential signal
Animal studies only: in mice, semax boosted the dopamine release amphetamine produces. FDA found no human study of abuse potential.
No study in people. This rests on animal studies.
The numbers and sources
- How common
- How often is not known: the sources give no rate.
- Effect
- FDA reported that in mice, semax increased the dopamine release that amphetamine produces in the striatum, a response FDA notes is typically induced by drugs of abuse. FDA found no studies that would inform semax's abuse potential [3].
- Population
- Animal studies (mice) reviewed by FDA [3].
- Sources
- [3]
- Caveats
- An animal finding. No human study of abuse potential was located by FDA [3].
Sources
- Gusev EI, Skvortsova VI, Miasoedov NF, et al. Effectiveness of semax in acute period of hemispheric ischemic stroke (a clinical and electrophysiological study). Zhurnal Nevrologii i Psikhiatrii imeni S.S. Korsakova. 1997. https://pubmed.ncbi.nlm.nih.gov/11517472/
- Gusev EI, Martynov MY, Kostenko EV, Petrova LV, Bobyreva SN. The efficacy of semax in the treatment of patients at different stages of ischemic stroke. Zhurnal Nevrologii i Psikhiatrii imeni S.S. Korsakova. 2018. https://doi.org/10.17116/jnevro20181183261-68
- U.S. Food and Drug Administration. FDA Briefing Document: Semax-Related Bulk Drug Substances (Semax (free base) and Semax acetate). Pharmacy Compounding Advisory Committee, July 23-24, 2026. 2026. https://www.fda.gov/media/193348/download
- U.S. Food and Drug Administration. Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks. 2026. https://www.fda.gov/drugs/human-drug-compounding/certain-bulk-drug-substances-use-compounding-may-present-significant-safety-risks
- U.S. Food and Drug Administration. Bulk Drug Substances Nominated for Use in Compounding Under Section 503A of the Federal Food, Drug, and Cosmetic Act. Updated April 22, 2026. 2026. https://web.archive.org/web/20260422215502/https://www.fda.gov/media/94155/download
- Bascom E. FDA committee recommends looser restrictions for several peptides. Healio. 2026. https://www.healio.com/news/primary-care/20260724/fda-committee-recommends-looser-restrictions-for-several-peptides
- U.S. Department of Health and Human Services. Enforcement Discretion Policy Regarding 503A Compounding Using Certain Peptide Bulk Drug Substances. Federal Register 91:68526. 2026. https://www.federalregister.gov/documents/2026/10/30/2026-22192/enforcement-discretion-policy-regarding-503a-compounding-using-certain-peptide-bulk-drug-substances
- U.S. Department of Health and Human Services. HHS Enforcement Discretion Policy Regarding 503A Compounding Using Certain Peptide Bulk Drug Substances, with Appendices A and B. 2026. https://www.hhs.gov/sites/default/files/hhs-503a-peptide-enforcement-discretion-policy-appendix-b.pdf
- Lebedeva IS, Panikratova YR, Sokolov OY, et al. Effects of Semax on the Default Mode Network of the Brain. Bulletin of Experimental Biology and Medicine. 2018. https://doi.org/10.1007/s10517-018-4234-3
- Tsai SJ. Semax, an analogue of adrenocorticotropin (4-10), is a potential agent for the treatment of attention-deficit hyperactivity disorder and Rett syndrome. Medical Hypotheses. 2007. https://doi.org/10.1016/j.mehy.2006.07.017
- Inozemtseva LS, Yatsenko KA, Glazova NY, et al. Antidepressant-like and antistress effects of the ACTH(4-10) synthetic analogs Semax and Melanotan II on male rats in a model of chronic unpredictable stress. European Journal of Pharmacology. 2024. https://doi.org/10.1016/j.ejphar.2024.177068
- Panikratova YR, Lebedeva IS, Sokolov OY, et al. Functional Connectomic Approach to Studying Selank and Semax Effects. Doklady Biological Sciences. 2020. https://doi.org/10.1134/s001249662001007x
- Lapochkin OL, Zykov VP, Zavadenko NN, et al. [Expert Council resolution: adjunctive pharmacotherapy for hyperkinetic disorders (attention deficit hyperactivity disorder) in children and adolescents]. Zhurnal Nevrologii i Psikhiatrii imeni S.S. Korsakova. 2026. https://doi.org/10.17116/jnevro2026126092126