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Semax

Research use

Synthetic peptide (ACTH fragment analogue)

Last updated 29 October 2026

Semax is a synthetic peptide of seven amino acids, based on a fragment of the natural hormone ACTH. It was developed in Russia, where a nasal spray form has been used for years as a medicine for conditions such as stroke recovery. Outside Russia it is sold as a nootropic, and the independent evidence for that use is thin.

Key points

Semax is a short peptide, a heptapeptide, derived from a fragment of ACTH, with a small tail added so it lasts longer in the body.
In Russia a nasal form is an approved medicine, used mainly in stroke and some other neurological conditions.
It is not licensed in the UK, and most of the human research comes from one region, which makes it hard to judge independently.
As a focus or memory aid, the honest position is that good quality evidence is limited.

Quick facts

What it is: Synthetic peptide, seven amino acids (ACTH fragment)
Studied for: Stroke recovery and neuroprotection; marketed as a nootropic
UK status: Not a licensed medicine; sold for research use
Elsewhere: A nasal form is an approved medicine in Russia
Human evidence: Mainly small studies from one region

How it works

Semax is thought to work differently from common nootropics, which tend to act on neurotransmitters directly. Research suggests it influences brain growth factors such as BDNF and NGF, the signals that help nerve cells survive and form connections, along with calming effects on inflammation. Most of this work is in animals and cell studies, so the picture in healthy people is far from settled.

What the evidence shows

The strongest human evidence comes from small studies in Russia, largely in people recovering from ischaemic stroke, where it has been used as a medicine. There is also animal and laboratory work on nerve protection and repair. What is missing is the larger, independent trials, especially in healthy people using it for focus or memory, that would be needed to license it or to recommend it with confidence.

What it does not settle

Little independent evidence exists outside its country of origin.
Benefits for memory or focus in healthy people are not well established.
Long term safety in wide use, and the quality of products sold online, are not assured.

Side effects

Common

Semax is usually reported to be well tolerated, with few side effects noted in the studies so far. Because those studies are small and mostly from one region, this is not a complete picture.

Less common but serious

There is no UK licensed product, so the dose, purity and contents of material bought online cannot be verified.

Report any suspected side effect through the MHRA Yellow Card scheme.

UK legal status and access

Semax has no UK marketing authorisation, so it is not a licensed medicine here and is not offered by registered clinics or pharmacies. The approved nasal medicine exists in Russia, not the UK. Products sold online are usually labelled for research use.

Common questions

What is Semax?

A synthetic seven amino acid peptide based on a fragment of the hormone ACTH, developed in Russia where a nasal form is an approved medicine.

Does it improve memory or focus?

It is marketed that way, but independent evidence in healthy people is limited, so the honest answer is that it is not well established.

Is it a licensed medicine in the UK?

No. A nasal form is approved in Russia, but Semax is not licensed in the UK.

The licensed route

There is no UK licensed Semax. A registered clinician can advise on memory, focus or mood concerns, and on options with stronger evidence behind them.

Factual reference only, not medical advice. We give no dosing for unlicensed compounds.

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