What It Is
Semax is a synthetic seven-amino-acid ACTH-fragment analogue with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. FDA treats Semax free base and Semax acetate as distinct bulk drug substances and found inconsistent naming in compounding nominations, so the exact material cannot be inferred from the word Semax alone.[1]
Semax is registered in Russia as nasal drops, but neither form is a component of an FDA-approved drug. Russian registration does not establish approval, product equivalence, or an accepted indication in the United States.[1]
How It Works
Mechanistic claims are primarily preclinical. Rat studies report changes in BDNF and TrkB expression and in immune- and vascular-related gene expression after experimental brain ischemia.[2][3] These observations show biological activity in specific animal models; they do not establish a clinical mechanism, cognitive benefit, or neuroprotection in people.
What the Research Shows
FDA's 2026 source review found insufficient evidence for Semax free base or acetate in cerebral ischemia, migraine, or trigeminal neuralgia. The clinical material available for those uses was sparse, poorly described, small, and in some cases showed no meaningful pain resolution; professional guidelines did not discuss Semax.[1]
A small placebo comparison reported short-term fMRI network changes after intranasal Semax, but a neuroimaging signal is not proof of improved memory, attention, mood, or daily function.[4] An older stroke publication is available only as limited Russian-language clinical literature and does not overcome the methodological gaps identified by FDA.[5]
Safety and Unknowns
There is no FDA-approved label or established U.S. human dose. FDA found no human pharmacokinetic study by any route, no safety data for the proposed subcutaneous route, and inadequate adverse-event reporting in most intranasal references. The agency also identified a possible bleeding concern from reported antithrombotic activity and unresolved risks from aggregation, impurities, and immunogenicity.[1]
Absence of reported adverse events in small or poorly reported studies is not evidence of safety. Pregnancy, lactation, interaction, repeated-use, pediatric, and long-term safety remain inadequately characterized.
Regulatory Status
Semax is not FDA-approved. In July 2026, FDA proposed not adding either Semax free base or Semax acetate to the section 503A Bulks List because of characterization gaps, inadequate effectiveness evidence, and safety uncertainties.[1][6] An advisory-committee proposal is not itself a final rule, but it is also not an approval or endorsement.