Health Library

Semax

Not FDA-approved

Also known as: ACTH(4-7)-Pro-Gly-Pro, Met-Glu-His-Phe-Pro-Gly-Pro

M E H F P G P
Structure source: PubChem CID 9811102

Semax is a lab-made chain of seven amino acids, based on a short piece of ACTH, a hormone made by the pituitary gland. It was developed in Russia to support thinking and protect the brain. Rat studies show it raises a brain growth factor; its human studies are small and come from Russia.

How it works

  • It is built from part of ACTH (amino acids 4 to 7) plus three more amino acids, proline-glycine-proline.
  • In rats, a single nasal dose raised BDNF, a growth factor that supports nerve-cell connections, about 1.4-fold in the hippocampus, a memory area.
  • In the same rats, it activated TrkB, the receptor BDNF works through, and improved a learned avoidance task.
  • In rat brain membranes it bound to specific sites, and a nasal dose raised BDNF in the basal forebrain within three hours.
  • In rats, it changed the activity of genes for two nerve growth factors, BDNF and NGF, differently in different brain areas.

Evidence

Brain protection and recovery after stroke

Early human evidenceCEBM Level 3-4

Small Russian studies in stroke patients reported faster recovery. Russian reports of better memory and attention in people exist, but they are uncontrolled or poorly described. No trial is registered in Western countries, and the growth-factor findings come from rats.

Caveats

  • The rat growth-factor results come from a single dose. They do not show how large any effect would be in people, or whether repeated use improves thinking.
  • No study has measured how it is absorbed or how long it lasts in people, by any route.
  • In rats it increased the blood's clot-dissolving activity, so it may add to bleeding risk. Anyone on a blood thinner or with a bleeding disorder needs a physician's review first.
  • It may strengthen the effects of stimulants and of MAO-inhibitor medicines.
  • Reported side effects include nasal irritation and mild headache. One unconfirmed report described eye pain and burning after the nasal drops, lasting at least a year.
  • In one Russian report, some patients showed seizure-like brain-wave activity after a dose.
  • There are no human safety data in pregnancy.

References

  1. Dolotov OV, et al. Brain Res. 2006;1117:54-60.
  2. Dolotov OV, et al. J Neurochem. 2006;97 Suppl 1:82-86.
  3. Shadrina M, et al. J Mol Neurosci. 2010;41:30-35.
  4. Gusev EI, et al. Zh Nevrol Psikhiatr Im S S Korsakova. 2018;118:61-68.
  5. Cherkasova KA, et al. Bull Exp Biol Med. 2001;132:625-626.

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Reviewed by Shubham Gupta, MD — Founder & President · October 31, 2026

This page is for education only. It is not medical advice. Decisions about any treatment belong with a physician who knows your history.