Which is better, Semax or Selank?
Both are graded human observational: neither has an indexed double blind placebo controlled trial, and both rely on studies from the developing Russian research groups. The tiebreaker is regulatory status. Semax was recommended by the Pharmacy Compounding Advisory Committee for the 503A bulks list in July 2026, while selank was not and sits in neither category after its nomination was withdrawn. If the goal is anxiety specifically, selank is the one studied for it, but approved anxiety treatments with real trials should come first. [1] [2] [3] [4] [5]
How do Semax and Selank compare?
| Dimension | SemaxFavored | Selank |
|---|---|---|
| What it is [6] [7] | Heptapeptide analog of ACTH fragment 4-10 (Met-Glu-His-Phe-Pro-Gly-Pro); does not stimulate cortisol release. | Heptapeptide analog of tuftsin (Thr-Lys-Pro-Arg), an immune peptide fragment of IgG, extended with Pro-Gly-Pro. |
| Note: Both use the same Pro-Gly-Pro tail for stability. | ||
| Main use studied [1] [2] [8] | Acute ischemic stroke recovery and chronic cerebrovascular insufficiency; cognitive and asthenic uses in Russian labeling. | Generalized anxiety disorder and neurasthenia. |
| Proposed mechanism [6] [7] | Raised hippocampal BDNF protein about 1.4 fold and trkB expression within hours of one intranasal dose in rats; monoamine and anti-ischemic effects in rodents. | Allosteric GABA-A modulation, inhibition of enkephalin degrading enzymes, and monoamine and BDNF effects in rodent and cell work. |
| Human evidence [1] [2] [3] [8] [9] [10] | Open comparative Russian stroke studies (1997, 2005, 2018) reporting faster neurological recovery and fewer exacerbations; no blinding or placebo. | Small Russian anxiety studies (2008, 2014, 2015), including a comparison with phenazepam reporting similar anxiety relief with less sedation; no placebo controlled trial. |
| Doses in the literature [1] [2] | Intranasal 12 to 18 mg per day (1% solution) for 5 to 10 days in acute stroke; roughly 0.2 to 2 mg per day (0.1% solution) for cognitive uses. | Intranasal 0.15% solution at roughly 0.3 to 2.7 mg per day for 10 to 14 days. |
| Reported side effects [1] [3] | Nasal irritation; anxiety, irritability, or insomnia reported anecdotally at higher doses. | Nasal irritation; fatigue or drowsiness reported anecdotally; less sedation than phenazepam in the comparative study. |
| FDA and compounding status [4] [5] | Removed from 503A Category 2 on April 15, 2026; PCAC recommended adding it to the 503A bulks list in July 2026; no final rule yet. | Nomination withdrawn, so no longer in Category 2, but not on the bulks list and not recommended by PCAC in July 2026; most 503A pharmacies will not compound it. |
| Typical cost [4] [5] | No lawful compounded price: not on the 503A bulks list, and advertised clinic prices are not a comparable price. | No lawful compounded price: selank is not on the 503A bulks list and was not recommended by PCAC in July 2026. |
| Note: Research chemical nasal sprays and vials are not lawful for human use. | ||
| WADA status [11] | Not named on the WADA Prohibited List; whether it falls under S0 (non-approved substances) is unclear, so tested athletes should confirm with their anti-doping organization. | Not named on the WADA Prohibited List; whether it falls under S0 (non-approved substances) is unclear, so tested athletes should confirm with their anti-doping organization. |
Evidence grade and regulatory status
Pulled from each peptide’s own record, so it stays in step with the peptide pages.
| Attribute | Semax | Selank |
|---|---|---|
| Class | Synthetic heptapeptide analog of ACTH fragment 4-10 (Met-Glu-His-Phe-Pro-Gly-Pro), a melanocortin derived nootropic and neuroprotective peptide | Synthetic heptapeptide analog of the immune tetrapeptide tuftsin (Thr-Lys-Pro-Arg) extended with Pro-Gly-Pro, a Russian anxiolytic peptide |
| What it is | Nasal peptide registered in Russia; rodent brain growth factor data and open label Russian stroke trials; not FDA approved; recommended for compounding in 2026. | Anti-anxiety nasal peptide registered in Russia, with small open label trials against a benzodiazepine; not FDA approved and not on FDA advisers' 2026 list. |
| Evidence | Evidence: Human observational evidence | Evidence: Human observational evidence |
| FDA status | Regulatory: Under FDA review | Regulatory: Removed from Category 2 (Apr 2026) |
| Compounding | Semax was placed on the FDA 503A Category 2 list (substances with significant safety risks) in 2023 and removed from it on April 15, 2026. On July 23 to 24, 2026 the Pharmacy Compounding Advisory Committee recommended adding semax to the 503A bulks list. As of the last verification date FDA has not published a final rule, so compounding pharmacies and state boards vary in whether they will fill it. It is not an FDA approved drug and is not eligible for 503B outsourcing. It is a registered prescription drug in Russia. | Selank was placed on the FDA 503A Category 2 list (substances with significant safety risks) in 2023. The FDA Category 2 page current as of April 22, 2026 now lists selank acetate under bulk drug substances nominated but withdrawn, so it is no longer in Category 2, but it is not on the 503A bulks list and was not among the peptides the Pharmacy Compounding Advisory Committee recommended on July 23 to 24, 2026. With no active nomination and no listing, a 503A pharmacy has no federal basis to compound it from bulk, and state boards cannot authorize what federal law does not. It is not an FDA approved drug and is not eligible for 503B outsourcing. It is a registered prescription drug in Russia. |
| WADA | WADA: WADA status unclear | WADA: WADA status unclear |
| Routes | Intranasal drops (Russian product and most sold forms), Subcutaneous injection (as sold, no published human data) | Intranasal drops (Russian product and most sold forms), Subcutaneous injection (as sold, no published human data) |
| Typical cost | No lawful compounded price: Semax is not on the 503A bulks list, and PCAC's July 2026 recommendation is advisory until FDA publishes a final rule. Advertised clinic prices are not a comparable price. Products sold as research chemicals are not lawful for human use and are not verified for identity or purity. | No lawful compounded price: selank is off 503A Category 2 but is not on the 503A bulks list and was not recommended by PCAC in July 2026. Advertised clinic prices are not a comparable price. Products sold as research chemicals are not lawful for human use and are not verified for identity or purity. |
| Last verified |
Has Semax been tested directly against Selank?
No published trial has compared Semax and Selank directly. The dimensions above come from separate studies and labels, and cross-trial comparisons are less reliable than a direct trial.
What do Semax and Selank cost?
| Dimension | Semax | Selank |
|---|---|---|
| Typical cost | No lawful compounded price: Semax is not on the 503A bulks list, and PCAC's July 2026 recommendation is advisory until FDA publishes a final rule. Advertised clinic prices are not a comparable price. Products sold as research chemicals are not lawful for human use and are not verified for identity or purity. | No lawful compounded price: selank is off 503A Category 2 but is not on the 503A bulks list and was not recommended by PCAC in July 2026. Advertised clinic prices are not a comparable price. Products sold as research chemicals are not lawful for human use and are not verified for identity or purity. |
| Price detail | Semax price by channel | Selank price by channel |
Where a price index exists, the range is the cash price per month across branded, compounded, and telehealth channels, without insurance. The cost pages give each channel separately with its sources. Otherwise the typical cost from the peptide record is shown. Legal access depends on your state: see peptide legality by state.
Frequently asked questions
What is the difference between semax and selank?
Semax is built from a fragment of ACTH and was studied mainly for stroke recovery and cognition; selank is built from the immune peptide tuftsin and was studied mainly for anxiety. Both are intranasal Russian prescription peptides with the same stabilizing Pro-Gly-Pro tail. [1] [2] [6] [7]
Can semax and selank be used together?
No study has tested the combination, so any benefit or risk of using both is unknown. They are proposed to act on different systems, semax on BDNF and monoamines in rats and selank on GABA and enkephalin breakdown, which is the reasoning behind combined nasal products. Neither has FDA approval, and only semax was recommended for the 503A bulks list in July 2026, so there is no lawful US source for a combined product. [5] [6] [7]
Which is better for anxiety?
Selank is the one studied for anxiety: small Russian studies reported reduced anxiety scores and effects similar to phenazepam with less sedation. None were placebo controlled, so the effect is not established by Western standards. [2] [3]
Which is better for focus or memory?
Semax has the more relevant data, mostly stroke recovery studies and rat work showing increased hippocampal BDNF. No placebo controlled trial in healthy adults has tested either one for focus or memory. [1] [6] [9]
Can I get semax or selank from a US pharmacy?
Semax was recommended for the 503A bulks list by the Pharmacy Compounding Advisory Committee in July 2026, so some pharmacies may compound it depending on the state board. Selank is off Category 2 but was not recommended, and most pharmacies will not make it. Neither is FDA approved. [4] [5]
Are semax and selank allowed in sport?
Neither is named on the WADA Prohibited List. Because both are non-approved substances, S0 could apply, so tested athletes should confirm with their anti-doping organization before use. [11]
Conditions studied
From the blog
- N-acetyl semax and selank amidate: is there any human data?
What N-terminal acetylation and C-terminal amidation are claimed to change in semax and selank, what the lab studies actually found, and why no human study has tested either modified version.
- Selank nasal spray: the evidence, and combining it with semax
What the intranasal selank studies measured, whether the route matters, and what is known about semax and selank nasal spray together: no trial has tested the combination.
- Selank withdrawal: dependence, benzodiazepines, and alcohol
Does selank cause withdrawal? What studies measured on dependence, how it compares with benzodiazepines, the rodent alcohol and opioid withdrawal studies, and the untested alcohol interaction.
- Semax nasal spray: what the intranasal studies show
Semax was developed in Russia as nasal drops. What the intranasal stroke and imaging studies measured, how nasal and injected data compare, and what the July 2026 PCAC vote means.
Sources
Numbered citations above point to these primary sources. PubMed entries link to the indexed abstract.
- [1]Gusev EI et al. Effectiveness of semax in acute period of hemispheric ischemic stroke (a clinical and electrophysiological study). Zh Nevrol Psikhiatr Im S S Korsakova 1997PubMed 11517472, 1997
- [2]Zozulya AA et al. Efficacy and possible mechanisms of action of a new peptide anxiolytic selank in the therapy of generalized anxiety disorders and neurasthenia. Zh Nevrol Psikhiatr Im S S Korsakova 2008PubMed 18454096, 2008
- [3]Medvedev VE et al. A comparison of the anxiolytic effect and tolerability of selank and phenazepam in the treatment of anxiety disorders. Zh Nevrol Psikhiatr Im S S Korsakova 2014PubMed 25176261, 2014
- [4]FDA: Bulk drug substances used in compounding under section 503A of the FD&C Act (links to the Category 1, 2, and 3 lists and the bulks list)FDA, 2026
- [5]FDA Pharmacy Compounding Advisory Committee meetings (July 2026 meeting on peptide nominations)FDA, 2026
- [6]Dolotov OV et al. Semax, an analog of ACTH(4-10) with cognitive effects, regulates BDNF and trkB expression in the rat hippocampus. Brain Res 2006PubMed 16996037, 2006
- [7]Vyunova TV et al. Peptide-based anxiolytics: the molecular aspects of heptapeptide selank biological activity. Protein Pept Lett 2018PubMed 30255741, 2018
- [8]Gusev EI et al. Semax in prevention of disease progress and development of exacerbations in patients with cerebrovascular insufficiency. Zh Nevrol Psikhiatr Im S S Korsakova 2005PubMed 15792140, 2005
- [9]Gusev EI et al. The efficacy of semax in the treatment of patients at different stages of ischemic stroke. Zh Nevrol Psikhiatr Im S S Korsakova 2018PubMed 29798983, 2018
- [10]Medvedev VE et al. Optimization of the treatment of anxiety disorders with selank. Zh Nevrol Psikhiatr Im S S Korsakova 2015PubMed 26356395, 2015
- [11]WADA Prohibited ListWADA, 2026
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