Cognitive / Nootropic
Semax
Met-Glu-His-Phe-Pro-Gly-Pro · ACTH(4-10) analog
What it is
Semax is a seven-amino-acid synthetic peptide developed at Moscow State University in the 1980s. It's a fragment of ACTH (adrenocorticotropic hormone) with one extra Pro-Gly-Pro tail that protects it from breakdown enzymes. In Russia, it's an approved drug for stroke recovery, transient ischemic attacks, and several cognitive disorders — and is widely used as a "Limitless"-style nootropic by biohackers worldwide.
How it works
Semax has two main effects:
- Boosts BDNF (brain-derived neurotrophic factor) — BDNF is sometimes called "fertilizer for the brain" because it supports new neuron growth, synaptic plasticity, and learning. Animal studies show Semax increases BDNF protein 1.4x and BDNF mRNA 3x in the hippocampus within hours.
- Modulates the dopamine and serotonin systems — produces alertness, focus, and motivation similar to stimulants but without dopamine receptor overstimulation. This is why users describe it as "Adderall without the crash."
Because it's delivered intranasally, it crosses the blood-brain barrier directly and acts within minutes.
Benefits
- Sharp focus and clean energy without stimulant side effects
- Improved working memory and verbal fluency
- Faster learning and information retention
- Enhanced mood and reduced fatigue
- Neuroprotection against ischemic damage (stroke recovery)
- Reduced anxiety and stress markers
- Some evidence for ADHD-like symptom reduction
- No "crash" or rebound depression
Timeline
- 15–30 min
- Effects begin. Cleaner alertness, sharper focus.
- 2–4 hours
- Peak effect. Re-dose if needed (every 4–6 hours typical).
- Day 3–7
- Cumulative effect — mood and motivation lift becomes steadier.
- Week 2–4
- Long-term BDNF effects compound — learning and memory improvements.
Dosing & titration
Standard concentration0.1% solution (1 mg/mL) for general use; 1% solution for therapeutic indications
Starting dose200–400 mcg per nostril, 1–2x daily
Standard daily600–1,000 mcg total per day, split across 2–3 doses
Therapeutic (post-stroke)Up to 6,000 mcg/day — only under medical supervision
Cycle length5 days on, 2 off; or 6 weeks on, 2 weeks off
When to titrate upIf 200 mcg doesn't produce noticeable focus shift, increase to 400 mcg per dose. The N-Acetyl version of Semax is more potent — consider switching rather than going much higher.
Side effects & risks
- Mild nasal irritation or rhinitis
- Headache (rare, usually with overdose)
- Some users experience vivid dreams
- Fatigue if used too late in the day (interferes with sleep)
- Diminished effect with continuous daily use — cycle properly
Sourcing matters: Quality varies wildly because most Western users buy from research chemical sources. Russian-pharmaceutical-grade is the gold standard. Contraindicated in pregnancy, severe psychiatric disorders, and seizure disorders.
Typical price
$30–$80/mo
Intranasal spray bottle (3 mg/mL × 3 mL typical). Russian pharmacy versions are often cheaper but harder to source legally in the US.
Studies
- Semax, an analog of ACTH(4-10) with cognitive effects, regulates BDNF and trkB expression in the rat hippocampus — Foundational mechanism paper. PubMed Brain Research, 2006
- Semax, an analogue of adrenocorticotropin (4-10), binds specifically and increases levels of BDNF protein in rat basal forebrain — Showed direct binding and BDNF response. PubMed Journal of Neurochemistry, 2006
- Semax and Pro-Gly-Pro Activate the Transcription of Neurotrophins After Cerebral Ischemia — Stroke recovery mechanism. PubMed Central International Journal of Molecular Sciences, 2024
- The efficacy of Semax in the treatment of patients at acute stages of ischemic stroke — Russian clinical trial showing improved neurological recovery. PubMed Zhurnal Nevrologii i Psikhiatrii, 2018
Educational reference only. Not medical advice. Semax is not FDA-approved; it's an approved pharmaceutical in Russia and Ukraine. Use only under guidance of a licensed prescriber.