Head to head

Selank vs Semax

Nootropic

Two compounds that are more often stacked than compared — the side-by-side data, and what actually separates them.

Verdict

Not an either/or

Selank and Semax appear in each other's stacks in this dataset, so the most common real-world use is together rather than instead of. If you do have to pick one, let route and schedule decide it — Selank is intranasal, subcutaneous, twice daily; Semax is intranasal, subcutaneous, twice daily — because the evidence does not separate them cleanly enough to do it for you.

What you are actually choosing between

Before anything else: the dataset lists Selank and Semax in each other's stacks. They are run together more often than they are chosen between, so if you came here for a winner, the first honest answer is that this may not be an either/or.

Both are classed here as nootropics, so this is a within-class choice: the mechanism is broadly shared and what separates them is kinetics, route, and how much has actually been tested.

The overlap is focus and cognition. On this site's goal weighting — an editorial priority score, not a measure of effect size — Selank rates 3/5 for focus and cognition and Semax rates 5/5.

The evidence

Neither has an evidence edge — both sit at the same tier. Selank: approval from a regulator somewhere, though not a current FDA or EMA label; a registered Russian medicine; the trials are small and Russian-language. Semax: approval from a regulator somewhere, though not a current FDA or EMA label; a registered Russian medicine; Western trial data is essentially absent. Anyone telling you one is clearly better supported than the other is going beyond what is published.

How they differ in practice

No half-life is published for either compound in this dataset. That absence is itself information: it means the pharmacokinetics have not been characterized well enough to quote, so both dosing schedules — twice daily for Selank, twice daily for Semax — are convention.

Committed time differs: Selank runs 2 weeks, Semax runs 4 weeks.

Source notes

What the evidence actually says

Verbatim, so you can check the verdict above against what it was built from.

Selank

A synthetic heptapeptide analogue of the immune peptide tuftsin, again with a Pro-Gly-Pro tail added for stability. Its character is anxiolytic rather than stimulant, which is why it is usually paired with, not substituted for, Semax. Like Semax it is a Russian-registered intranasal medicine (commonly a 0.15% solution) and is NOT approved in the US or EU; the human evidence is small Russian trials in generalised anxiety disorder and adjustment disorder, some comparing it against benzodiazepines such as phenazepam, and it has not been independently replicated in Western trials. Route matters: it is an intranasal drug, not an injectable. Russian clinical dosing runs to roughly 1800-2700 mcg per day divided across two or three administrations; the per-dose range here reflects the more conservative doses typical of non-clinical use rather than the full trial daily total. Plasma half-life is minutes, so no hourly figure is listed. Courses are conventionally short (10-14 days) rather than continuous.

Semax

A synthetic heptapeptide: the ACTH(4-7) fragment extended with a Pro-Gly-Pro tail that blocks rapid enzymatic breakdown. It has no ACTH-like hormonal activity. Semax is a registered medicine in Russia and is given intranasally as a 0.1% or 1% solution; it is NOT approved in the US or EU and Western trial data is essentially absent, so the human evidence base is Russian-language and mostly from a small number of groups. Route matters here: it is an intranasal drug, not an injectable, and the nose-to-brain path is the whole point of the formulation. Russian dosing convention for cognitive and asthenic indications is roughly 200-2000 mcg per day split across two or three administrations (a few drops or sprays per nostril); the per-dose range listed here reflects that split, not the daily total. Much higher doses (around 12 mg/day of the 1% solution) have been used in acute ischaemic stroke under hospital supervision and are outside the scope of self-directed use. Plasma half-life is measured in minutes, so no meaningful hourly figure is listed; reported CNS effects outlast plasma presence.

Side by side

The numbers

Selank compared with Semax
Attribute	Selank	Semax
Class	Nootropic	Nootropic
Routes	Intranasal, Subcutaneous	Intranasal, Subcutaneous
Dose range	150 mcg–900 mcg (typical 300 mcg)	100 mcg–1 mg (typical 300 mcg)
Frequency	Twice daily	Twice daily
Half-life	Not characterized	Not characterized
Cycle length	2 weeks	4 weeks
Experience	Intermediate	Intermediate
Evidence	Approved elsewhere	Approved elsewhere
Contraindications	Pregnant / nursing Under 18	Pregnant / nursing Under 18
Side effects	Nasal stinging or irritation at the spray site Drowsiness or blunted drive, more likely at the top of the range Mild headache Bitter taste or post-nasal drip after spraying	Nasal stinging, dryness or irritation at the spray site Mild headache Overstimulation, irritability or restlessness, dose-dependent Disturbed sleep if dosed late in the day

Turn a typical dose into a mark on the syringe: SelankSemax

Goals

Where they overlap, and where they do not

Goal	Selank	Semax
focus and cognition	Selank: 3/5	Semax: 5/5
neuroprotection	Selank: 2/5	Semax: 4/5
recovery and sleep	Selank: 4/5	Semax: 2/5
immune supportone only	Selank: 2/5	Semax: —

They overlap on 3 goals and diverge on 1. Weights are this site’s editorial priority score out of 5 — how central a goal is to why people use a compound. They are not effect sizes and two 5s do not mean two equal results.

Go deeper

MonographSelankMechanism, protocol, storage, sources.MonographSemaxMechanism, protocol, storage, sources.ToolReconstitution calculatorTurn either dose above into a mark on the syringe.

Other comparisons with these two

Educational information only, not medical advice. Talk to a licensed clinician before starting, changing, or stopping anything.