Selank vs Semax: both are 7-amino-acid nasal peptides from the same Moscow institute, but Selank is used for anxiety and is sold over the counter in Russia, while Semax is used for stroke and cognitive problems and is a Russian prescription drug.[1][2][4] Selank’s best data are small trials in 60 to 70 anxiety patients;[9][11] Semax’s are open-label stroke studies of about 110 patients.[12] Neither is FDA-approved.
Users often describe Selank as calming and Semax as stimulating. Below we compare how they work, what the human studies found, label doses, side effects and their US legal status. Full details are in our Selank profile and Semax profile, and more options are on the nootropic peptides hub.
At a glance
| Selank | Semax | |
|---|---|---|
| Built from | Tuftsin, an immune peptide[1] | A fragment of the hormone ACTH[2] |
| Shared feature | Pro-Gly-Pro stabilizing tail[4] | Pro-Gly-Pro stabilizing tail[4] |
| Russian status | Over-the-counter anxiety medicine[1] | Prescription drug (0.1% and 1%)[2][3] |
| Main uses | Anxiety, nervous exhaustion, stress-related sleep problems[1] | Cognitive problems, stroke recovery, optic nerve disease[2] |
| Typical effect reported | Calming | Alerting, focus |
| Best human data | Small anxiety trials vs benzodiazepines[9] | Small, mostly open-label stroke studies[12] |
| US status | Not approved; nomination withdrawn[16] | Not approved; advisers voted 8 to 5 for compounding[15] |
How they work
Selank appears to slow the breakdown of enkephalins, the body’s own calming opioid peptides,[5] and changed the activity of GABA-related genes in rats.[6] GABA is the system that benzodiazepines act on, which fits its anti-anxiety use.
Semax raised the brain growth factor BDNF and its receptor in the rat hippocampus after one nasal dose[7] and increased dopamine and serotonin activity in rodents.[8] That fits its use for brain recovery and its “stimulating” reputation, but FDA reviewers described its mechanism as poorly understood.[14]
Both rest mainly on animal and lab work for mechanism. Neither has a confirmed receptor target in people.
They are siblings by design. Moscow researchers took a short natural peptide fragment and added the same three-amino-acid Pro-Gly-Pro tail to each, to slow breakdown in the body.[4] Even so, Selank’s maker reports it leaves the blood within about 5 minutes, and both Russian labels call for several doses a day rather than one.[1][2]
What the human studies found
Selank for anxiety
| Study | Patients | Result |
|---|---|---|
| Selank vs medazepam | 62 with generalized anxiety or neurasthenia | Similar anxiety relief, plus anti-fatigue effects[9] |
| Selank vs phenazepam | 60 with anxiety disorders | Clear anxiety relief lasting about a week after stopping[10] |
| Phenazepam with or without Selank | 70 with anxiety disorders | Faster response and fewer sedation and memory side effects[11] |
Comparing Selank with a benzodiazepine sounds impressive, but without a placebo group it’s hard to know how much of the improvement came from the drug itself, from time, or from expectations. Anxiety trials often show large placebo responses. These were short treatment courses, so they say little about long-term use.[9][11]
Semax for the brain
- Stroke: in 110 patients recovering from ischemic stroke, those given Semax had higher blood BDNF and better daily-living scores.[12]
- Healthy volunteers: in a placebo-controlled brain-imaging study, Selank and Semax each changed resting brain network activity, in different ways.[13]
- FDA’s view: its 2026 review judged the evidence for stroke, migraine and trigeminal neuralgia insufficient and found no human pharmacokinetic studies.[14]
Label doses compared
Both are dosed by drops in Russia, and a doctor sets the dose.
| Selank 0.15% | Semax 0.1% | Semax 1% | |
|---|---|---|---|
| Strength | 1.5 mg per mL[1] | 50 mcg per drop[2] | 500 mcg per drop[3] |
| Typical schedule | 2 drops per nostril, 3 times daily[1] | 2 to 3 drops per nostril, 2 to 4 times daily[2] | Higher daily doses in hospital[3] |
| Course | 14 days, repeatable after 1 to 3 weeks[1] | 3 to 14 days for most uses[2] | 10 days for acute stroke[3] |
Selank’s maker reports about 93% absorption through the nose and clearance from the blood within about 5 minutes.[1] Injectable versions sold online were never studied in these trials, and FDA found no safety data for injected Semax.[14] For unit conversions, see our peptide calculator.
Side effects and who should avoid them
| Selank | Semax | |
|---|---|---|
| Label side effects | Allergic reactions; unpleasant taste[1] | Mild nasal irritation with long use[2] |
| Not for | Pregnancy, breastfeeding, under 18[1] | Seizure history, acute psychiatric conditions, anxiety disorders, pregnancy[2] |
| FDA concerns | Lacks human safety information[16] | Immune reactions, impurities, possible abuse potential[14] |
The Semax label’s anxiety contraindication matters: people with an anxiety disorder who are considering Semax for focus are in the group its Russian label says should not use it.[2]
Can you take Selank and Semax together?
Online stacking guides often pair them, with Selank meant to “smooth out” Semax. No clinical trial has tested the combination; the one study that included both gave each to separate groups.[13] Because Semax is contraindicated in anxiety disorders and Selank is used for anxiety, the people most drawn to the stack may be the ones the Semax label excludes.[2] Also, Belgian authorities have found both peptides in seized, unlabeled products, a reminder that online versions may not contain what they claim.[18]
Legal status in 2026
- Semax: in July 2026, FDA’s Pharmacy Compounding Advisory Committee voted 8 to 5 to recommend it for the 503A bulks list, against FDA staff advice. FDA has not finalized that, so pharmacies still cannot routinely compound it.[14][15]
- Selank: not approved; its nomination was withdrawn and it was not reviewed in 2026.[16]
- Sport: neither is named on WADA’s 2026 list; because both are approved in Russia, their status is unclear, so athletes should ask their anti-doping organization.[19]
See Dihexa vs Semax vs Selank for how a third “nootropic” compares, and the FDA peptide ban in 2026 for the regulatory background.
Who each may suit: questions for your clinician
- Anxiety: ask how Selank’s small, unblinded trials compare with approved treatments, and whether it could interact with any sedatives you take.[11]
- Focus or memory complaints: ask what could be behind them, since Semax has not been tested for cognitive enhancement in healthy people.
- After a stroke: ask about proven rehabilitation and secondary-prevention steps; Semax’s data are open-label.[12]
- Seizures or a psychiatric condition: tell your clinician, because the Semax label lists a seizure history and acute psychiatric conditions as reasons not to use it.[2]
- Pregnancy or breastfeeding: both Russian labels list pregnancy as a contraindication, and Selank’s label also excludes breastfeeding and people under 18.[1][2]
The verdict
If the question is “which fits which goal,” the Russian labels answer it: Selank for anxiety, Semax for brain recovery and cognition. If the question is “which works,” the honest answer is that neither has been proven by large, independent, placebo-controlled trials, and neither is approved in the US. For sleep-focused peptides, see DSIP vs melatonin.
