Semax vs. Selank: What Actually Separates Them
Same Russian research program, same seven-amino-acid backbone shape, and constantly confused for each other. The trials behind them, and now their regulatory paths, aren’t the same at all.
Reviewed by the PepGuard team · Last reviewed Jul 28, 2026
Photo: Jens Lelie / UnsplashRelated, not interchangeable.
| Attribute | Semax | Selank |
|---|---|---|
| Parent molecule | ACTH(4-7) fragment | Tuftsin analog |
| Studied for | Stroke recovery, cerebrovascular insufficiency | Anxiety, neurasthenia |
| Registered use (Russia) | Prescription nootropic / neuroprotective, nasal drops | Prescription anxiolytic, nasal drops |
| Combined trial patients | ~300 (Gusev 2005 + 2018) | 122 (Zozulia 2008 + Medvedev 2014) |
| Evidence score | 40/100 | 38/100 |
| FDA compounding nomination | Withdrawn (Category 2) | Withdrawn (Category 2, as Selank acetate/TP-7) |
| July 23-24, 2026 PCAC agenda | On the agenda | Not on the agenda |
One faces an FDA review. The other doesn’t.
Neither peptide is FDA-approved, and both took the same first step toward US compounding legitimacy: a 503A Category 2 nomination, later withdrawn. That's where the similarity ends. Semax was placed on the agenda for the FDA’s Pharmacy Compounding Advisory Committee meeting on July 23-24, 2026, specifically for evaluation as a treatment for cerebral ischemia, migraine, and trigeminal neuralgia, not the nootropic use most searches for it are actually about. Selank was not on that agenda. As of this writing there’s no scheduled US regulatory review of Selank at all.
We haven’t independently verified the outcome of that meeting. Check the committee’s public record before treating either peptide’s current US legal status as settled, especially if you’re reading this after that date.
What the trials used, side by side.
| What's cited | Range |
|---|---|
| Registered stroke-recovery dose (Gusev et al. 2018, n=110, intranasal) | 6,000 mcg/day, two 10-day courses separated by a 20-day interval |
| Earlier cerebrovascular-insufficiency trial (Gusev et al. 2005, n=187, intranasal) | exact daily dose not specified in the available abstract; same registered route as above |
| Commonly cited nootropic dose (vendor/community, intranasal, no disease-specific trial behind this use) | 200-600 mcg/day, split into 2-3 doses |
| Commonly cited injectable dose (vendor-reported, zero human trials use this route) | 300-600 mcg/day, subcutaneous |
| What's cited | Range |
|---|---|
| GAD/neurasthenia trial (Zozulia et al. 2008, n=62, vs. medazepam) | intranasal, per Russian clinical protocol; exact mcg/day not specified in the available abstract |
| Anxiety-disorder trial (Medvedev et al. 2014, n=60, vs. phenazepam) | intranasal, over a defined treatment course; exact mcg/day not specified in the available abstract |
| Commonly cited Russian clinical-protocol dose (secondary sources, not independently verified) | 2 drops (~150 mcg) of a 0.15% intranasal solution, three times daily, for up to 14 days |
| Commonly cited nootropic/anxiolytic dose (vendor/community, intranasal) | 300-900 mcg/day, split into 2-3 doses |
| Commonly cited injectable dose (vendor-reported, zero human trials use this route) | 300-600 mcg/day, subcutaneous |
Nearly tied, by different measures.
Selank’s whole pitch is what it doesn’t cause.
The specific point of Selank’s comparator trials was anxiolytic effect without the sedation and muscle relaxation typical of the benzodiazepines it was tested against. Semax, studied for a different job entirely, has occasional anecdotal reports of jitteriness and sleep disruption instead.
| Signal | Frequency | Context |
|---|---|---|
| Nasal irritation or mild burning at instillation | commonly reported | Consistent with intranasal drug delivery generally; the Russian clinical literature describes it as mild and transient. |
| Serious adverse events in the published stroke-recovery trials | rarely reported | The Gusev trials (100+ patients combined) reported clinical benefit without a distinct safety signal, but neither was designed or powered as a dedicated safety study the way an FDA Phase 3 program would be. |
| Jitteriness, agitation, or sleep disruption | occasionally reported | Anecdotal, from vendor and community sources describing off-label nootropic use, not measured in the published disease-outcome trials. |
| Effects of injectable administration | unknown / not studied | No completed human trial has tested Semax delivered by injection. Every study cited on this page used intranasal administration. |
| Long-term or cumulative effects of chronic nootropic use in healthy adults | unknown / not studied | The published trials were short courses (10-day blocks) in stroke or cerebrovascular-insufficiency patients, not healthy adults using it for sustained cognitive enhancement. |
| Signal | Frequency | Context |
|---|---|---|
| Nasal irritation at the instillation site | commonly reported | Consistent with intranasal delivery generally, not specific to Selank's mechanism. |
| Shifts in immune markers (IL-6, Th1/Th2 balance) | occasionally reported | A published trial in anxiety-asthenic patients measured real changes in these markers, framed by its authors as beneficial immunomodulation rather than an adverse effect, but it's a genuine physiological effect worth disclosing. |
| Sedation, muscle relaxation, or psychomotor impairment | rarely reported | The specific point of the published comparator trials is that Selank produced anxiolytic effects without the sedation and muscle relaxation typical of the benzodiazepines it was compared against. |
| Effects of injectable administration | unknown / not studied | No completed human trial has tested Selank delivered by injection. Every study cited on this page used intranasal administration. |
| Interaction with autoimmune conditions or immunosuppressant therapy | unknown / not studied | Given the measured immune-marker shifts, no published trial has specifically studied Selank in people with autoimmune disease or on immunosuppressants. |
Every claim above, traced back.
Seven Russian clinical trials across both peptides, a shared human brain-imaging study, and current FDA compounding and advisory-committee records. Click through and check them yourself.
Semax vs. Selank, answered.
They're related but built for different jobs. Semax is derived from ACTH and studied mainly for stroke recovery and cognitive/neuroprotective effects; Selank is derived from tuftsin and studied for anxiety and neurasthenia. One published human study scanned 52 healthy volunteers on both peptides in the same design and found distinct effects on brain connectivity for each, so they aren't interchangeable versions of the same thing.
Neither is FDA-approved. Both were nominated for the FDA's 503A Category 2 compounding list and both nominations were withdrawn. But their regulatory paths diverged from there: Semax was placed on the agenda for the FDA's Pharmacy Compounding Advisory Committee meeting on July 23-24, 2026, for evaluation as a treatment for cerebral ischemia, migraine, and trigeminal neuralgia. Selank was not on that agenda, and there's no scheduled US review of it. We haven't independently verified the outcome of that meeting, so check the committee's public record before treating either peptide's regulatory status as settled.
No published trial has tested combining them. They were developed for different indications, studied in separate patient populations, and the one study that scanned both in the same design (the 52-person fMRI trial) tested them independently, not as a combined protocol. Community "stacking" of the two isn't backed by any combined-use research.
They're close. By patient count, Semax's stroke-recovery trials cover roughly 300 combined patients (Gusev et al. 2005 and 2018); Selank's anxiety trials cover 122 combined patients across its two active-comparator studies. Evidence scores reflect that near-parity: Semax scores 40, Selank scores 38. Neither trial set is placebo-controlled or FDA-registered, so both fall short of what would back a US approval.
Read the full report on each.
This is a preview of what PepGuard tracks on both.
Create your account to check any peptide, or build a stack, against the full research base.