Semax
Met-Glu-His-Phe-Pro-Gly-Pro (ACTH(4-10) analogue)
A Russian-developed ACTH fragment studied for attention, stroke recovery and BDNF expression, without the hormonal activity of ACTH itself.
Last reviewed · 2 references
How it works
Semax is a synthetic fragment of adrenocorticotropic hormone with the hormonal portion removed. Within an hour of intranasal dosing, rodent studies show sharp increases in BDNF and its receptor TrkB in the hippocampus. It also appears to slow the breakdown of enkephalins and to modulate dopaminergic and serotonergic tone. In Russia it holds regulatory approval for stroke and cognitive indications; elsewhere it is unapproved.
Early human data. Some human data exists, usually small, open-label, or from a single research group.
What the research reports
- Increased BDNF and TrkB expression in hippocampus (rodent, within 1h)
- Improved attention and working memory in small human studies
- Neuroprotection and functional recovery in ischaemic stroke trials conducted in Russia
- Reduced anxiety-like behaviour without sedation in animal models
What it has not been shown to do
- No large multi-centre trial outside Russia has replicated the stroke results
- Not demonstrated as a treatment for major depressive disorder
- Long-term safety beyond a few months is uncharacterised
Dosing reference
Research literature commonly reports 200–600 mcg/day intranasally, split across doses. Clinical stroke protocols used substantially higher amounts under supervision.
Calculate my dose for Semax- Routes studied
- Intranasal, Subcutaneous
- Half-life
- Very short in plasma (minutes); central effects reported to outlast it considerably
- Cycle length in the literature
- Studies typically run 10–14 days, then a break
Working out a draw volume from a vial? Use the free reconstitution calculator.
Side effects and contraindications
Reported side effects
- Nasal irritation with intranasal use
- Headache
- Overstimulation or irritability at higher amounts
- Sleep disruption if dosed late in the day
Do not use if
- Pregnancy and breastfeeding
- Uncontrolled anxiety or bipolar disorder — stimulating effects can destabilise
- Concurrent MAOIs or stimulants without clinical oversight
The practice that shares the mechanism
BDNF opens a plasticity window; it does not decide what gets encoded. That is the argument for pairing a BDNF-raising compound with deliberate mental rehearsal rather than passive use. Focused practice during the window is what turns raised plasticity into a changed pattern.
What amplifies it
- Deep sleep — BDNF-dependent consolidation happens overnight, not during the dose
- Adequate protein: the compound cannot outrun a shortage of amino acid substrate
- Zone-2 cardio independently raises BDNF and stacks additively
Mechanism hubs
- BDNF & neuroplasticityHow BDNF-raising peptides open a plasticity window — and why what you do during that window determines whether anything changes.
- Dopamine & driveWhat dopamine actually governs, why anhedonia is a motivation problem rather than a pleasure problem, and where peptides and practice fit.
Stacks that include it
- Cognitive clarityA plasticity-first approach to fog and flat focus: what the BDNF compounds do, what they cannot do alone, and the practice that fills the window.
- Mood & motivationFor anhedonia and flat drive: the inflammation and plasticity angles, and why the practice half carries most of the weight here.
Common questions
- It is registered in Russia for stroke and certain cognitive indications. It is not approved by the FDA, EMA or MHRA, and outside Russia it is sold only as a research chemical.
- Both come from the same Russian research programme, but they pull in different directions. Semax is derived from ACTH and skews stimulating and pro-attention. Selank is derived from tuftsin and skews anxiolytic and calming. People researching both often report using them at opposite ends of the day.
- There is no trial evidence that it treats depression. The interest comes indirectly: depression research has moved toward a neuroplasticity model, and Semax raises BDNF in animals. That is a mechanistic rationale, not a demonstrated outcome.
Sources & evidence notes
Some human data exists, usually small, open-label, or from a single research group.
Confidence score 27/100
Limited confidence
Animal or mixed preclinical work. Enough to justify interest, not enough to predict an outcome in a person.
Showing 2 of 2 sources
- 1.
Neuroscience Letters, 2006 · Source (opens in a new tab)
Animal studyLimited gradeRodent or other animal model. Frequently fails to replicate in people. - 2.
Zhurnal Nevrologii i Psikhiatrii, 2011 · Source (opens in a new tab)
Human trialModerate gradeHuman data, but open-label, uncontrolled, or from a single group.