Semax
Synthetic ACTH fragment analogue · No UK brand. Approved as a medicine in Russia
- UK status
- Unlicensed in the UK
- Availability
- Research use only
- Evidence base
- Russian clinical use, limited Western trial data
- Controlled drug
- No
Sequence
Heptapeptide, an analogue of ACTH fragment 4-10 with an added tripeptide tail.
The short version
What it does
Sold for focus, memory, mental clarity and recovery after a stroke. In Russia it is a licensed medicine for post-stroke cognitive recovery.
How it does it
Copies a fragment of a hormone your body makes under stress, minus the stress-hormone effects. It appears to raise a protein in the brain that helps nerve cells survive and form new connections.
The catch
It has decades of real medical use, but almost all of it in Russia and Eastern Europe, with the kind of trial data Western regulators do not accept. The FDA found the available studies small, uncontrolled or contradictory.
Everything below goes into the detail, with sources.
Semax is the awkward case in this register. It is not a research chemical invented for the wellness market. It is a licensed medicine in Russia with decades of clinical use behind it, and Western regulators still will not have it.
01What it is
ACTH is a hormone released under stress, which drives cortisol production. Researchers noticed that a short fragment of it, residues 4 to 10, had effects on learning and memory without the hormonal effects. Semax is a synthetic analogue of that fragment with an added tripeptide tail that makes it far more stable.
It is usually given as a nasal spray, which is unusual and practical: the nasal route gets a peptide closer to the brain than swallowing it would.
02How it came about
Semax was developed in the Soviet Union in the 1980s at the Institute of Molecular Genetics in Moscow and has been in clinical use in Russia since the 1990s. Its approved Russian indication centres on post-stroke cognitive recovery, and it has also been used for transient ischaemic attack and optic nerve conditions.
It had been evaluated by the FDA's compounding advisory committee before, and that earlier review resulted in withdrawal from positive listing. The July 2026 meeting was a re-evaluation, and this time it passed.
03UK legal and licensing status
Semax has no MHRA marketing authorisation and no FDA or EMA approval. It cannot be lawfully supplied for human use in the UK without one.
Russian approval is real regulatory approval under a real system, and dismissing it entirely would be wrong. But regulators differ substantially in the trial evidence they require, and the MHRA has not assessed this compound. There is no UK SPC, no approved patient information, and no Yellow Card coverage.
04How it works
The most cited mechanism is an increase in brain-derived neurotrophic factor, BDNF, a protein involved in nerve cell survival and in forming new connections. Effects on dopamine and serotonin signalling have also been reported, along with antioxidant activity.
Because it derives from an ACTH fragment stripped of the hormonal portion, it is not expected to raise cortisol.
05What it is not
Claims that attach themselves to this compound and do not hold up.
- Not licensed in the UK, the EU or the US. Russian approval does not transfer.
- Not a proven cognitive enhancer in healthy people. Its Russian indication is recovery after stroke, which is a different question from sharpening a healthy brain.
- Not backed by the trial evidence Western regulators require. The FDA described the available studies as small, uncontrolled or contradictory.
06What the evidence shows
There is a substantial Russian-language clinical literature, and decades of prescribing. That is more real-world use than almost anything else in this register can claim.
The FDA's assessment was that available studies were small, uncontrolled or contradictory. Long clinical use tells you a drug has not obviously killed anyone, which is worth something. It does not establish effect size, and without controls you cannot separate the drug from expectation, from natural recovery, or from everything else a stroke patient receives.
There is a real critique that this bar is biased towards Western trial designs and that Eastern European evidence gets discounted unfairly. That critique deserves engaging with rather than dismissing. It also does not conjure controlled data that does not exist.
Effect size in healthy adults, long-term safety outside supervised Russian practice, and any Western controlled trial data. Product identity and purity from grey-market sources is unverifiable as usual.
07Reported harms
Russian clinical use reports a benign profile, and it is prescribed to stroke patients, which implies tolerability. But without a UK or US licence there is no authoritative frequency table and no Yellow Card route.
The FDA specifically noted limited safety information for the proposed routes of administration, and nasal delivery of an unregulated product carries its own contamination concerns.
08Interactions and cautions
No Western interaction dataset. Effects reported on dopamine and serotonin signalling mean anyone on antidepressants or other psychiatric medication should treat this as genuinely unknown territory rather than assume it is inert.
09Stopping
No withdrawal syndrome described in the available literature.
10Monitoring
In Russian practice, a clinician oversees it. Bought online for self-directed cognitive enhancement, nobody is overseeing anything.
11Questions worth asking
Take these to a doctor or pharmacist. A good clinician will not mind being asked, and the answers are specific to you in a way nothing on this page can be.
- Is my situation anything like the stroke recovery population it is actually approved for?
- Am I taking anything that affects serotonin or dopamine?
- What would I accept as evidence that it works in healthy people?
12Common questions
Is Semax approved anywhere?
Yes, in Russia, where it has been a licensed medicine since the 1990s, principally for post-stroke cognitive recovery. It has no MHRA, EMA or FDA approval.
Does Semax improve focus in healthy people?
Not established. Its clinical use is in recovery after stroke and related conditions. Improving an impaired brain and enhancing a healthy one are different questions, and the second has not been properly tested.
Why did the FDA reject it before?
An earlier advisory committee review resulted in withdrawal from positive listing for compounding. The July 2026 meeting was a re-evaluation with the opportunity to present new evidence, and it passed 8 to 6.
13Sources
Links go to the authoritative source. Where a document sits behind a paywall or moves around, the full citation is given so you can find it yourself.
- Bulk drug substances review, SemaxFDA
- PCAC July 2026 meeting materialsFDA
- Semax clinical literaturePubMed
- Unlicensed medicines guidanceMHRA
14Change history
Every substantive change to this record is logged here with its date. Corrections are made openly, not quietly.
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