Semax is a synthetic peptide derived from a fragment of ACTH, developed in Russia and studied there as an approved nasal-spray product for cognitive and neuroprotective indications. It is not approved by the FDA or EMA and is sold elsewhere strictly as a research compound.
Benefits
Semax is a synthetic heptapeptide, an analog of ACTH(4-10). It's an approved pharmaceutical in Russia, used clinically there for decades including in stroke care — giving it a real human trial history unlike most research-only peptides, though the trial below is non-randomized and not placebo-controlled, a meaningfully weaker design than a standard RCT.
Mechanism — animal studies (single intranasal dose): produced a 1.4-fold increase in a key brain-growth protein (BDNF), elevated downstream receptor signaling, and improved learning performance in treated animals. Dolotov et al., Brain Res, 2006
Human trial — post-stroke rehabilitation (n=110, non-randomized, no placebo control): patients received Semax 6,000mcg/day intranasally in two 10-day courses. This was associated with increased BDNF, accelerated functional recovery, and improved motor scores — with earlier-rehabilitation patients (89±9 days post-stroke) showing a larger effect than later-rehabilitation patients (214±22 days post-stroke). Gusev et al., Zh Nevrol Psikhiatr Im S S Korsakova, 2018
Dosage
Human (intranasal, stroke rehabilitation trial): 6,000mcg/day, two 10-day courses with a 20-day gap. Community-use cognitive-enhancement protocols commonly discussed (250-1,000mcg intranasally, 1-3x/day) are a different, smaller dosing pattern than the stroke-rehabilitation trial — this smaller pattern wasn't what was clinically tested.
Side Effects
The stroke-rehabilitation trial's available abstract doesn't detail a structured adverse-event breakdown. Broader safety commentary describes intranasal Semax as generally well-tolerated with occasional mild nasal irritation — this specific claim wasn't independently verified against a primary source in this research pass.
Results Timeline
Human stroke trial: earlier intervention post-stroke was associated with a better response — a real, if population-specific, timing signal. No timeline data exists for the smaller cognitive-enhancement dosing pattern commonly discussed in research-use contexts.
Is Semax approved anywhere?+
Yes, it has regulatory approval in Russia as a prescription nasal spray, but it is not approved by the FDA or EMA.
What is Semax researched for?+
Cognitive function, focus, and neuroprotection are the most common research themes, largely from Russian-language clinical literature.
Is Semax the same as Selank?+
No, they are different peptides developed by the same research group, with Semax more associated with cognitive research and Selank more associated with anxiolytic research.
What is it actually doing in the brain?+
Its main claim to fame is rapidly boosting BDNF — brain-derived neurotrophic factor, a protein central to memory formation, neuroplasticity, and neuron survival. A single dose has been shown to raise BDNF and its receptor activity in the hippocampus within hours.
Is it related to ACTH — does that mean hormonal side effects?+
It's derived from a fragment of ACTH (the hormone that triggers cortisol release), but with the hormonally active piece stripped out and a stabilizing tail added instead. So the lineage is there, but Semax isn't functioning as a hormone in your body — the ACTH connection explains its origin, not its effects.
How is it typically dosed?+
As a nasal spray, typically 200-600mcg, once to three times daily, often first thing in the morning. A commonly cited cycle runs 10-14 days on, then roughly a week off, rather than continuous daily use indefinitely.
How fast does it actually reach the brain?+
Quickly — intranasal delivery gets it into the hippocampus and cortex within 30-60 minutes, with measurable changes from a single dose rather than something needing weeks to build up.
Does it do anything besides memory/BDNF?+
Yes — it also touches dopamine and serotonin activity, and gene-expression studies have found it affects hundreds of genes clustered around immune response and blood vessel function, beyond the neuroplasticity angle it's best known for.
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