Evidence · Small human studies
Semax
What it is
A synthetic seven-amino-acid peptide based on a fragment of ACTH (a pituitary hormone). It was developed in Russia, where it is registered as a medicine, including for stroke.
How it’s thought to work
Animal studies report increases in BDNF (a nerve-growth signal) and effects on several neurotransmitter systems.
What the research shows
- —Clinical studies are mostly Russian, small, and not run to the standard FDA would require.
- —Little independent research outside Russia.
Risks and side effects
- —Limited safety data. Nasal irritation is the most commonly reported problem.
- —FDA cites possible immune reactions and says it has too little information to know whether it causes harm.
Regulatory status
- —Not approved by FDA for any use.
- —FDA put it in “category 2” of its compounding policy — substances that may present significant safety risks. The nomination was later withdrawn, and in April 2026 FDA moved it to the “nominated but withdrawn” list on the same page, which still sets out its safety concerns. Withdrawal does not make it approved, and it does not place it in category 1 (the substances FDA is still evaluating for compounding).
- —It was one of the peptides reviewed at FDA’s Pharmacy Compounding Advisory Committee in July 2026. The committee’s votes are recommendations only; as of 2 October 2026 FDA has not added it to the list of substances pharmacies may compound.
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