Comparison

Semax vs Selank

The two Russian-origin nootropic peptides people most often compare — different parent sequences, different observed profiles in logs.

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Last updated: May 6, 2026

Field

Semax

Selank

Where Semax and Selank actually diverge

	Semax	Selank
Cadence	7/wk	7/wk
Concentration on example	2.50 mg/mL	2.50 mg/mL
Math weeks per vial	1.7	2.3
Category	Cognitive	Cognitive

Bolded values are the higher of the two on numeric rows. Same-value rows aren't a verdict — they're shared properties.

Semax vs Selank: the actual decision

These two molecules sit in the same general bucket — Russian-origin neuropeptide analogs developed in Soviet-era research labs and used clinically in Russia for stroke recovery and anxiety respectively — but the parent sequences are completely different. Semax is derived from a fragment of ACTH(4-10); selank is derived from tuftsin, a tetrapeptide fragment of an immunoglobulin heavy chain. The shared label of nootropic peptide hides genuinely different chemistry.

Observed effect profile in logs reflects that chemistry difference. Semax logs tend to emphasize cognitive endpoints — focus, working-memory feel, and the cleaner verbal-fluency signal the published Russian work centers on. Selank logs tend to emphasize anxiolytic and mood endpoints, with the published evidence base built around generalized anxiety rather than acute cognitive performance. Neither molecule is approved outside Russia, and the human evidence base is much thinner than the marketing volume on either suggests.

Mechanism, cadence, and what shows up in a log

Administration is unusual for both — intranasal is the standard route in the published Russian work and the most common route in research-peptide logs as well, with subcutaneous as a less-common alternative. Per-dose milligrams are in the same general range (typically 250–1000 mcg per administration for either). The vial math on either molecule reconstituted at the same concentration produces similar unit counts on a 100-unit syringe; the calculator pages linked below handle the conversion.

Cadence is daily for both, often multi-administration during a cycle and then off for a similar period. The two molecules can be logged in parallel without much workflow conflict because they target different self-reported endpoints — a stacked semax-and-selank log usually has one cognitive-feel field and one anxiety-feel field, with administration timestamps for each molecule rather than a merged event timeline.

Semax vs Selank: the numbers, side by side

Start with what actually goes into a syringe. The example Semax vial on this site reconstitutes 5 mg in 2 mL of bacteriostatic water — about 2.50 mg per mL, which yields roughly 12 doses at the 0.4 mg example and lasts about 1.7 weeks at 7 doses per week. The example Selank vial reconstitutes 5 mg in 2 mL (2.50 mg/mL), which yields about 16 doses at 0.3 mg and stretches roughly 2.3 weeks at 7 doses per week. Those numbers are the starting point most people forget to write down, and they decide everything downstream — refill timing, unit count on the syringe barrel, and whether a 30-mL bac-water bottle stretches across one vial or two.

Category context matters too. Both Semax and Selank sit in the Cognitive bucket, so the head-to-head questions readers bring here are usually about cadence, titration step size, and which of the two molecules logs more cleanly inside a longer protocol rather than a from-scratch category choice. Cadence helps frame the rest: Semax is logged about 7× per week in the example schedule, Selank about 7×.

The single most-asked-about mistake on each page is worth surfacing here, because they rarely overlap. On the Semax side: Using the peptide continuously for months without taking any breaks. On the Selank side: Using tap water or sterile water instead of bacteriostatic water for reconstitution. Both are the kind of thing a tracked log catches early and an untracked routine catches late.

Frequently asked questions about Semax vs Selank

What's the difference between Semax and Selank?

Why is Semax often available as a nasal spray?

The nasal passages contain a rich blood supply and a direct pathway to the brain, partly bypassing what is known as the blood-brain barrier. For certain molecules like Semax, this intranasal route can allow for very rapid absorption and onset of action in the central nervous system. Many users prefer this method for its convenience and speed, although injectable forms allow for more precise dosing.

Does Semax feel like a stimulant like caffeine?

While many people report feelings of increased mental energy and focus, Semax is not a classical stimulant. Unlike caffeine or Adderall, it doesn't typically cause jitters, a crash, or a feeling of being 'wired.' Its mechanism is based on supporting brain cell health and neurotransmitter balance, leading to a more natural and sustainable state of enhanced cognition.

What is the difference between Selank and Semax?

Why is Selank usually administered as a nasal spray?

The intranasal route is common for Selank because it allows the peptide to be absorbed through the nasal mucosa and gain rapid access to the brain. This method bypasses the digestive system, where the peptide would be broken down, and avoids the first-pass metabolism in the liver. This is thought to lead to higher bioavailability in the brain compared to oral ingestion.

Are there different versions of Selank?

Yes, you might see terms like 'N-Acetyl Selank' or 'N-Acetyl Selank Amidate'. These are modified versions of the original Selank peptide. The 'N-Acetyl' and 'Amidate' chemical groups are added to the peptide structure to increase its stability and may alter its absorption and how it works in thebody. Users exploring these versions often report differences in potency and effect duration.

Related on Peptide Pilot

Log Semax and Selank side by side in the app

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