Semax: what the evidence shows

What Semax is

Semax is a synthetic peptide of seven amino acids: Met-Glu-His-Phe-Pro-Gly-Pro. It is an analogue of a fragment of adrenocorticotropic hormone, the stretch known as ACTH 4-10.

The two differ in the last three amino acids. Adding Pro-Gly-Pro makes the molecule much harder for the body's enzymes to break down, which is why the analogue exists at all.

Semax is a registered drug in Russia, sold there as nasal drops at 0.1 percent and 1 percent. It has never held FDA approval, and what circulates in the United States comes through the research-chemical channel or a compounding pharmacy.

Why the evidence question here is different

For most compounds in this market, the honest summary is that the human research does not exist. Semax is the case where it exists and cannot easily be read.

When Semax came before the FDA Pharmacy Compounding Advisory Committee in July 2026, the agency found references on its use in cerebral ischemia published in Russian, some with English abstracts. It did not consider them.

The reason is procedural rather than scientific. A federal rule requires that foreign-language material submitted to the agency be accompanied by a verified English translation together with the translator's name and qualifications. None was supplied, so those references sat outside the evaluation.

Nothing about that says the studies were bad. It says they were not in a form the agency could formally weigh. Anyone reporting the outcome of that review as proof that no Semax research exists is drawing a conclusion the review does not support.

What the review could weigh, and what it found

Two references survived that filter. Both are small and neither is controlled.

One is a meeting abstract from 2002 in which Semax was given to rats and to an unstated number of people with chronic ischemic brain disease, intranasally for ten days. FDA noted that the authors did not say which subjects the laboratory measurements came from, did not give full results, and did not report clinical function before or after.

The other is a 1996 study in adults with migraine, trigeminal neuralgia or dental plexalgia. Twelve people in the migraine group received a single intranasal dose. Four of the twelve reported their headache stopped within 90 to 120 minutes. In the other eight the authors described the effect as weaker, with pain reduced but not eliminated.

FDA listed the limitations: small sample, no blinding, no control group, no reported scores or standard deviations, and insufficient detail on how the study was designed and run. Its conclusion was that the evidence is insufficient to support Semax for headache pain in migraine.

Professional society guidelines for treating cerebral ischemia and for treating migraine do not mention Semax at all.

The census, and what its zero is measuring

A PubMed search in September 2026 returns 207 records naming Semax. Forty-six carry the index tag for humans, four are tagged as clinical trials of any type, and one is tagged as a randomized controlled trial. That one is a 2007 study of motor neuron disease published in a Russian neurology and psychiatry journal.

Through the identical filters in the same session, aspirin returns 7,015 clinical trials and 5,085 randomized controlled trials, and a nonsense term returns zero. The search itself is working.

ClinicalTrials.gov returns no registered study naming Semax as an intervention. Aspirin returns 2,181 through the same query in the same session.

Read that registry zero carefully. ClinicalTrials.gov is a United States registry, and a drug developed, approved and studied in Russia has no particular reason to appear in it. The zero is a fact about which registry was searched as much as a fact about the compound.

The safety picture, including one finding worth knowing

FDA stated that it could not find pharmacokinetic studies in humans for Semax by any route, and that there are no safety data for the subcutaneous route the nomination proposed. The only route discussed in the literature it reviewed was intranasal.

One reference raised a specific clinical concern. A study discussing possible antithrombotic properties led the agency to flag a bleeding risk, particularly for people already at risk of bleeding or taking other medications that increase it. Compounded products do not carry labeling that would warn about that.

The nonclinical work carries a separate flag. In rodents Semax shows neuroprotective, antithrombotic, analgesic and anxiety-reducing effects through mechanisms that are poorly understood. In mice it also increased amphetamine-driven dopamine release in the striatum, which the reviewers noted is the kind of response typically produced by drugs of abuse. FDA found no toxicity studies addressing abuse potential.

That is a mouse observation and it belongs in that category. It is reported here because it is in the public record and it does not appear in any consumer description of the compound.

What is reviewed and what is sold

Regulators evaluated Semax for cerebral ischemia, migraine and trigeminal neuralgia. The proposed products were an intranasal spray or a subcutaneous injection.

FDA's survey of how it is actually marketed in the United States runs much wider. It lists anxiety, depression, attention and memory improvement, stroke, nerve regeneration, diabetic neuropathy and attention deficit disorder. It also lists opioid withdrawal, motor neuron disease, Parkinson's disease, Alzheimer's disease, optic nerve atrophy, pain and gastric protection.

The agency noted that a nomination for attention deficit disorder was not evaluated because supporting literature for that use was not found. A nomination for use as a nootropic was folded into the cerebral ischemia assessment, because there is no diagnostic code and no treatment guideline for it.

How this compound is graded here

Semax sits in the lowest of the three evidence tiers used on this site: no controlled human evidence. The tier describes what has been published in a form that can be checked, and it is not a judgment on Russian medicine.

A longer human history than most compounds in this market is real and it is worth acknowledging. It has not produced the controlled, translated, inspectable trial base this site requires before grading a compound higher.

FDA proposed not adding either form of Semax to the compounding list, citing chemical characterization gaps, missing endotoxin data for injection, immunogenicity concerns and insufficient evidence of effectiveness for the three conditions it assessed. The Semax board carries the dated regulatory position.

Sources

Each document below is named as it names itself, with the date printed on that document rather than the day it was read.

1. FDA Briefing Document for Semax-Related Bulk Drug Substances, Pharmacy Compounding Advisory Committee — U.S. Food and Drug Administration, May 2026
2. Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks — U.S. Food and Drug Administration, April 2026
3. Meeting of the Pharmacy Compounding Advisory Committee — agenda and uses evaluated — U.S. Food and Drug Administration, July 2026
4. The study of chronic partial denervation and quality of life in patients with motor neuron disease treated with semax — Zhurnal Nevrologii i Psikhiatrii imeni S.S. Korsakova, January 2007
5. PubMed literature census for Semax, run with a positive control through the same filters — National Library of Medicine, September 2026
6. Registered study census for Semax, run with a positive control through the same query — ClinicalTrials.gov, National Library of Medicine, September 2026