What is Semax?
Semax is a synthetic peptide made of seven amino acids: Met-Glu-His-Phe-Pro-Gly-Pro. The first four come from adrenocorticotropic hormone (ACTH), a pituitary hormone involved in the stress response. The last three, Pro-Gly-Pro, were added to make the peptide more resistant to breakdown. Unlike full ACTH, this fragment is not known to drive the adrenal glands to make cortisol, so it is studied for its effects on the brain rather than on stress hormones.
Semax was developed by scientists at the Institute of Molecular Genetics in Moscow, and it has been used clinically in Russia, mainly as nasal drops. Modified versions, such as N-acetyl Semax amidate, also circulate. These have much less published research, and claims that they are stronger or longer lasting rest mostly on anecdote rather than solid data.
How does Semax work?
Researchers do not fully understand how Semax works. In rat studies, it raised levels of brain-derived neurotrophic factor (BDNF) and its receptor, TrkB, in the hippocampus, a brain area involved in memory. BDNF supports the survival of nerve cells and the formation of new connections between them. Animal research also suggests Semax affects dopamine and serotonin signaling. In rat models of stroke, researchers reported changes in the activity of many genes, including ones tied to blood vessels, inflammation and nerve cell survival.
What has research looked at?
- Stroke recovery
- Russian clinical studies in people recovering from ischemic stroke reported better recovery of movement and daily function in groups given Semax. These studies were generally small and did not meet the standards of large modern trials.
- Memory and attention
- Rat studies reported better performance on learning and memory tasks. Small human studies, mostly in Russia, reported effects on attention and memory, but these have not been confirmed in large independent trials.
- Nerve protection
- In animal and cell models of reduced blood flow and nerve damage, researchers reported that Semax helped nerve cells survive. This is early-stage evidence.
- Mood and stress
- In rodent studies, Semax reduced some stress-related and depression-like behaviors. Human data on mood are very limited.
Overall, the evidence is limited in quality. Most studies come from a small number of Russian research groups, and many are published only in Russian. Large, independent, placebo-controlled trials have not been done, so it is not known how well these findings hold up.
Semax vs Selank
Semax and Selank are often mentioned together because both are short Russian peptides that share the same stabilizing Pro-Gly-Pro tail. They come from different starting points. Semax is built on a fragment of ACTH and is researched mostly for stroke recovery, memory and attention. Selank is built on tuftsin, a small immune peptide, and is researched mostly for anxiety. Both have limited data from outside Russia.
Side effects and cautions
In the Russian clinical literature, Semax is generally described as well tolerated, but long-term safety has not been studied in large trials. Most other reports come from informal accounts, which are not reliable data. Russian prescribing information lists acute psychosis, anxiety disorders, a history of seizures, pregnancy and breastfeeding as reasons not to use it. Anyone considering a brain-active compound should talk to a qualified clinician.
- Nasal irritation
- Semax is usually given as nasal drops in its clinical use, and local irritation of the nose can occur.
- Anecdotal reports
- Informal reports describe headache, irritability, anxiety, fatigue and trouble sleeping. These have not been measured in controlled studies.
- Limited data outside Russia
- Few studies have been done elsewhere, and interactions with other medicines are largely unknown.
Further reading
This page summarizes the research in plain words. To read the studies yourself:
- Published studies on Semax PubMed, US National Library of Medicine
