Underground Biohacking
Cognition

Semax

Chris Hallewell, founder of Underground Biohacking

By , Founder, Underground Biohacking

Last reviewed

Prescription medication in Russia and Ukraine. Research compound elsewhere. Not FDA-approved.

Semax is a lab made peptide based on a fragment of ACTH, a human hormone. Russia registered it as a drug for stroke and poor brain blood flow. The human evidence is real but thin. Most trials are Russian, small, and not blinded to modern standards. Western regulators have never reviewed it. The FDA says it does not have enough safety information to know whether Semax would harm people. Treat it as promising but unproven.

What is Semax?

Semax is a peptide built from seven amino acids. Its chemical string is Met-Glu-His-Phe-Pro-Gly-Pro. Russian researchers designed it from a piece of ACTH, the hormone that tells your adrenal glands to release cortisol. The copied piece covers positions four to seven of that hormone. The last three units are proline, glycine and proline. That tail is not part of the natural hormone. Chemists added it when they built the peptide. Semax is called an ACTH analogue, but the published work describes it as having no hormone activity of its own. Researchers group it with nootropics and neuroprotective agents. A nootropic is a substance studied for its effects on thinking and memory. Structure is the whole point here. Papers describe Semax as the ACTH(4-7) fragment joined to a Pro-Gly-Pro tail. Russian trials gave Semax into the nose, both in stroke patients and in healthy volunteers. Russia registered it as a medicine, and that registration applies in Russia only. It has never been through an approval review in the United States or Europe.

What is Semax used for?

  • In 110 people recovering from ischemic stroke, Semax raised blood BDNF levels and sped up functional recovery and motor scores.[1]Human study
  • In 30 patients treated during acute ischemic stroke, Semax added to standard care sped the recovery of damaged neurological function.[2]Human study
  • In 187 people with cerebrovascular insufficiency, Semax improved symptoms and lowered the reported risk of stroke and transient ischemic attacks.[3]Human study
  • A 1997 review by the peptide's own developers reported that Semax improved memory and attention in healthy men working under extreme conditions.[4]Human study
  • In healthy adults scanned before and after an intranasal dose, one resting brain network was larger in the Semax group than in the placebo group.[5]Human study
  • In rats with a blocked brain artery, Semax turned down inflammation genes and turned up genes used for nerve signalling.[6]Animal or lab study only
  • In rats with induced damage to the prefrontal cortex, Semax protected brain tissue and prevented the expected memory loss.[7]Animal or lab study only
Semax dosage chart
Typical dose200-600mcg per day intranasal, split into 2-3 doses
Cycle length10-20 days on, 10 days off
FormIntranasal spray

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How does Semax work?

Semax copies a short stretch of ACTH, the hormone that tells your adrenal glands to make cortisol. Chemists kept the brain active fragment and added three amino acids to the end. The result no longer drives cortisol release. It is usually given into the nose. In rat hippocampus, semax raises BDNF and its receptor TrkB. BDNF is a protein that helps neurons grow and form new connections. In rats it also shifts dopamine handling, and after a stroke it changes immune and blood vessel gene activity. In blood, semax slows the enzymes that break down enkephalins, your own opioid like peptides. These mechanism findings come from animals and cells.

How much Semax should you take?

200-600mcg per day intranasal, split into 2-3 doses

How long should you run Semax?

10-20 days on, 10 days off

How is Semax supplied?

Intranasal spray

What are the side effects of Semax?

EffectHow seriousWhat to watch
No independent, modern, blinded safety trial of Semax has been run outside Russia, so the true risk profile is unknown.UnknownNone
Bursts of abnormal electrical activity appeared on EEG in some patients with brain injury from oxygen loss after a Semax injection.[8]Potentially seriousBrain electrical activity at the first dose, plus any seizure like symptoms.
In a Russian study of 187 patients with cerebrovascular insufficiency, side effects were reported as few. The drug was described as well tolerated, including in older people.[3]Mild as reportedGeneral tolerance, especially in older adults.
A review by the peptide's developers reported no negative effects or complications across their own studies, which is an unblinded source with an obvious interest.[4]None reportedDo not read this as a safety clearance.

Is Semax legal in 2026?

Semax has no FDA approval in the United States for any use. It is registered as a medicine in Russia, and that is a Russian decision that carries no weight with United States regulators. Semax was nominated as a bulk drug substance for pharmacy compounding. The FDA placed it in category 2, the group flagged for possible significant safety risks. The nominator later withdrew it, so it now sits on the FDA's withdrawn list. The FDA's stated reason is blunt. Compounded semax may pose a risk for immunogenicity. The agency has no or limited safety information for the proposed routes of administration. It says it lacks enough information to know whether the drug would harm people. Checked 6 August 2026.

Status checked against the primary source.

Where to buy Semax

Running Semax in your next protocol cycle?

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Where to source it

The hard part with Semax isn't the protocol. It's finding a supplier that can prove what's in the vial. We assessed dozens against per-batch, third-party testing. A handful passed.

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Semax protocols

Deep dives on Semax

Frequently Asked Questions

Does Semax improve memory in healthy people?
Maybe, but the proof is weak. A 1997 review by the peptide's developers said Semax improved memory and attention in healthy men under hard conditions. That review gives no trial details you can check. A placebo controlled brain scan study in healthy adults did show a change in one resting brain network. A scan change is not the same as better recall. No modern, blinded, independently run cognitive trial exists. So nobody has proven it.
Is Semax legal or approved in the United States?
No. Semax has no FDA approval for any condition. It is registered as a medicine in Russia, and that is a Russian decision only. It was nominated for use in pharmacy compounding, then placed in the FDA's category 2 for possible significant safety risks. The nominator withdrew the nomination, so it now sits on the FDA's withdrawn list. Nothing in that history makes it an approved or lawfully compounded drug in America.
Why is nearly all the Semax research Russian?
Semax was designed in Russia and is sold there as a registered medicine. Russian institutes funded and ran almost all the trials. Many results appear in Russian language journals with short abstracts and few method details. Some studies came from the same teams that created the peptide. That is not proof of bias. It does mean no independent group elsewhere has repeated the key results. Until that happens, the evidence base stays narrow.
Is Semax safe?
Nobody can answer that with confidence. Russian trials report few side effects and good tolerance, including in older patients. One follow up study in brain injured patients saw bursts of abnormal electrical activity on EEG after injection. Those authors advised watching brain activity at the first dose. The FDA states it has no or limited safety data and cannot say whether Semax would harm people. There is no long term safety record from any independent regulator.
Does Semax help after a stroke?
The Russian evidence says yes, but it is not strong evidence. A trial in 110 people after ischemic stroke found faster recovery, better motor scores and higher blood BDNF. An earlier comparison in 30 patients found quicker regression of neurological deficit. Both were small and not blinded to modern standards. No large randomised trial outside Russia has tested it. Standard stroke care remains the proven route, and Semax is not part of it outside Russia.
Does Semax raise cortisol, since it comes from ACTH?
It should not. Semax copies only a short middle piece of ACTH, positions four to seven. Published work describes that piece as having no hormone activity of its own. The part of ACTH that drives cortisol release is not included. So Semax is grouped as a nootropic and neuroprotective peptide, not as a hormone. The abstracts of the Russian trials do not report cortisol measurements, so this point rests mainly on the chemistry rather than on measured human data.

References

  1. 1.Gusev EI, et al. (2018). [The efficacy of semax in the tretament of patients at different stages of ischemic stroke]. Zhurnal nevrologii i psikhiatrii imeni S.S. Korsakova. PMID: 29798983. DOI: 10.17116/jnevro20181183261-68.
  2. 2.Gusev EI, et al. (1997). [Effectiveness of semax in acute period of hemispheric ischemic stroke (a clinical and electrophysiological study)]. Zhurnal nevrologii i psikhiatrii imeni S.S. Korsakova. PMID: 11517472.
  3. 3.Gusev EI, et al. (2005). [Semax in prevention of disease progress and development of exacerbations in patients with cerebrovascular insufficiency]. Zhurnal nevrologii i psikhiatrii imeni S.S. Korsakova. PMID: 15792140.
  4. 4.Asmarin IP, et al. (1997). [A nootropic adrenocorticotropin analog 4-10-semax (l5 years experience in its design and study)]. Zhurnal vysshei nervnoi deiatelnosti imeni I P Pavlova. PMID: 9173745.
  5. 5.Lebedeva IS, et al. (2018). Effects of Semax on the Default Mode Network of the Brain. Bulletin of experimental biology and medicine. PMID: 30225715. DOI: 10.1007/s10517-018-4234-3.
  6. 6.Filippenkov IB, et al. (2020). Novel Insights into the Protective Properties of ACTH(4-7)PGP (Semax) Peptide at the Transcriptome Level Following Cerebral Ischaemia-Reperfusion in Rats. Genes. PMID: 32580520. DOI: 10.3390/genes11060681.
  7. 7.Romanova GA, et al. (2006). Neuroprotective and antiamnesic effects of Semax during experimental ischemic infarction of the cerebral cortex. Bulletin of experimental biology and medicine. PMID: 17603664. DOI: 10.1007/s10517-006-0445-0.
  8. 8.Alekseeva GV, et al. (1999). [Use of semax at a follow-up of patients with posthypoxic encephalopathy]. Anesteziologiia i reanimatologiia. PMID: 10199046.

This content is for educational purposes only. These compounds are intended for research use. Nothing here is medical advice.