PROTOCOL·18 May 2026·5 min read

Semax vs Selank — two tools, different jobs.

Both are short Russian-developed heptapeptides researched in cognitive and stress-response models. Both deliver fast via intranasal administration. They look like they should be interchangeable — they aren't. Semax pushes alertness up; Selank dials anxiety down. Different mechanisms, different timeslots, often paired in the Cognitive Stack bundle.

The short version.

Semaxis the deep-work peptide. Research subjects describe a clean, anxiety-free alertness — the kind you'd use when sitting down to write a paper or analyse a dataset. The dopaminergic + BDNF mechanism gives it a cognitive-edge profile without the stimulant after-crash.

Selankis the decision-under-pressure peptide. Almost the opposite framing — calms the GABA tone down, removes anxiety without sedating. Often described as "benzodiazepine-lite" without the dependence or cognitive fog.

Both research reference compounds — not for human consumption.

Side-by-side.

PropertySemaxSelank

ClassACTH(4-10)-derived heptapeptide (nootropic)Tuftsin-derived heptapeptide (anxiolytic)

OriginRussian Academy of Medical Sciences, 1980sRussian Academy of Medical Sciences, 1990s

Primary effectDopaminergic + BDNF-modulating · pro-cognitive, alertness, focusGABAergic + serotonergic · anxiolytic, calming, decision-clarity

Application routeIntranasal (most common in research) · subcutaneous works tooIntranasal · subcutaneous works too

Onset15–30 minutes intranasal10–20 minutes intranasal

Half-life (active effect)≈ 3–4 hours from a single dose≈ 4–6 hours from a single dose

Typical research dose300–900 µg intranasal · 1–3× per day300–900 µg intranasal · 1–2× per day

Sweet spotDeep-work blocks, writing, pre-presentation, research data analysisDecision-making under pressure, post-stressor recovery, calmer focus

Variants available5 mg · 10 mg · 30 mg per vial5 mg · 10 mg · 30 mg per vial

Single-kit price (10 vials)from €69.90 (5 mg) · €119.90 (10 mg) · €169.90 (30 mg)from €69.90 (5 mg) · €119.90 (10 mg) · €169.90 (30 mg)

ReconstitutionBAC water · stable 28–42 days at 2–8 °CBAC water · stable 28–42 days at 2–8 °C

Which one fits your research?

Pick Semax alone if

· Cognitive-edge studies: focused tasks, sustained attention, working-memory measures.
· Pre-task model: subject performs better when alert-but-not-jittery.
· You explicitly want dopaminergic mechanism in scope.

Shop Semax →

Pick Selank alone if

· Stress-response models, post-stressor recovery time, anxiety-related endpoints.
· Decision-making under load is the dependent variable.
· You want anxiolytic effect without sedation or addictive potential.

Shop Selank →

Stack both if

· You want the standard cognitive-protocol pair (Semax morning, Selank afternoon).
· Research scope covers both alertness AND anxiety endpoints.
· Cognitive Stack bundle saves ~8 % vs buying both separately.

Cognitive Stack bundle →

All compounds are research reference material — not for human consumption. Questions? Email the lab.