Synthetic neuropeptide (ACTH(4-10) analog)
Met-Glu-His-Phe-Pro-Gly-Pro (MEHFPGP)
Semax is a synthetic heptapeptide derived from a fragment of adrenocorticotropic hormone (ACTH(4-10)), modified with a Pro-Gly-Pro tail to resist enzymatic breakdown. It was developed in the Soviet Union and later Russia, where it has been studied since the 1980s and is registered as a medication.
It is classified as a nootropic and neuroprotective peptide. In Russia and Ukraine it is an approved prescription medicine used in neurology — for example, in the management of ischemic stroke and certain cognitive and optic-nerve conditions. Outside these countries it has no marketing approval and is most often encountered as a grey-market "research chemical."
DrugText.org provides this information for educational, harm-reduction purposes. It is not medical advice and is not an endorsement to acquire or use Semax. Much of the peer-reviewed evidence originates from Russian-language research, and large independent Western trials are limited.
Semax is reported to increase expression of brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF), along with their receptors, particularly in the hippocampus. These neurotrophins support neuronal survival, growth, and synaptic plasticity, which underlies the peptide's proposed neuroprotective and cognitive effects.
Research suggests Semax modulates the dopaminergic and serotonergic systems and influences the melanocortin system (consistent with its ACTH-fragment origin). These actions are thought to contribute to its reported effects on attention, mood, and stress resilience.
Semax has been shown to inhibit enkephalin-degrading enzymes, prolonging the action of the body's endogenous enkephalins (opioid-like peptides). This is one proposed route for its analgesic and anti-stress properties.
Pharmacokinetic note: Semax has a very short plasma half-life (degraded within minutes), yet its central nervous system effects are reported to persist for hours. The Pro-Gly-Pro modification slows enzymatic degradation relative to the unmodified ACTH fragment.
Important distinction: The approved clinical uses above are supported by Russian medical research and regulatory approval. The nootropic/off-label effects are largely based on user reports and small studies, and have not been validated by large independent Western trials.
The information below is descriptive of what is reported in the literature and by users. It is not a dosing recommendation and not a substitute for medical supervision.
The primary and clinically established route is intranasal (drops or spray), which delivers the peptide to the CNS while bypassing first-pass metabolism. Some researchers also use subcutaneous injection. Oral administration is considered ineffective because the peptide is broken down in the digestive tract.
The original heptapeptide. Shorter duration of action; the form used in the Russian clinical formulations (0.1% and 1% intranasal solutions).
Reported dose range
Anecdotal nootropic range: ~200–600 mcg/day intranasal, often split into doses. Clinical formulations use defined concentrations under medical supervision.
A modified analog with an acetyl group on the N-terminus and an amide on the C-terminus. Reported to be more stable, more potent, and longer-acting than plain Semax.
Reported dose range
Anecdotal range is lower than plain Semax due to increased potency; users commonly report ~100–300 mcg/day intranasal. Data are limited.
In Russian clinical use, Semax is generally described as well-tolerated with a low incidence of side effects. The most commonly reported issue is mild nasal irritation or discomfort from intranasal administration.
Most adverse-event data reflect pharmaceutical-grade product used under medical supervision. Grey-market peptides may differ substantially in purity, dose accuracy, and contamination, which can change the risk profile.
Semax is an approved, registered prescription medicine used in clinical neurology.
Semax is not approved by the FDA for any use and is not a recognized dietary ingredient. It is sold only as a "research chemical, not for human consumption." It is not currently a federally scheduled controlled substance, but selling it for human use is not lawful.
In most other countries Semax has no marketing authorization and its status ranges from unregulated to prohibited. Import rules vary. Always verify your local laws before assuming legality.
Sourcing reality: Because the legitimate supply is concentrated in a few countries, most product sold elsewhere comes from grey-market vendors with no regulatory oversight of purity or labeling.
Reputable suppliers provide a recent Certificate of Analysis (COA) from an independent lab showing identity and purity. Treat the absence of a COA as a red flag.
Lyophilized (freeze-dried) peptide is typically reconstituted with bacteriostatic water and kept refrigerated. Reconstituted peptide degrades over time; follow storage and stability guidance and use sterile technique.
If used, begin at the low end of reported ranges to assess individual response before considering any increase. More is not necessarily better with neuropeptides.
Counterfeit and under-dosed peptides are common in the grey market. Prefer vendors with consistent COAs, transparent sourcing, and a verifiable reputation.
Because interactions are poorly studied, be cautious when combining Semax with other CNS-active substances or medications, and consult a qualified clinician where possible.
Semax is an approved prescription medicine in Russia and Ukraine. It is not approved by the FDA in the United States and is not an approved medicine in most Western countries, where it is sold only as a 'research chemical, not for human consumption.' Legal status varies by jurisdiction — check your local laws.
In Russian clinical use Semax is generally reported to be well-tolerated, with nasal irritation being the most commonly noted side effect. However, long-term and large-scale safety data outside of Russian studies are limited, and drug interactions are largely unstudied. Grey-market products carry additional risks from unknown purity and contamination.
Plain Semax is the original heptapeptide and has a shorter duration of action. N-Acetyl Semax Amidate is a chemically modified version (acetylated N-terminus, amidated C-terminus) reported to be more stable, more potent, and longer-acting, so it is typically used at lower doses.
Russian clinical research supports its use for conditions such as ischemic stroke and certain cognitive and optic-nerve disorders. Nootropic/off-label benefits (focus, mental clarity, stress resilience) are reported anecdotally but have not been validated by large independent Western trials. Evidence outside of Russia remains limited.
This profile was compiled by the DrugText.org editorial team from published pharmacological literature, regulatory information, and documented user reports. Because much of the primary research on Semax is Russian-language and independent Western trials are limited, claims are framed accordingly.
Purpose: Educational, non-judgmental harm-reduction information. This page is not medical advice and does not encourage illegal acquisition or use.
Last reviewed: June 5, 2026
Corrections: If you have peer-reviewed data that improves this profile, contact us. We update profiles as new evidence becomes available.