Comparison
Both are Russian-developed neuropeptides administered nasally or via injection, but Semax leans toward stimulatory cognitive enhancement while Selank is more prominently researched for anxiolytic and stress-reducing properties.
| Attribute | Semax | Selank |
|---|---|---|
| Full name | Semax (ACTH 4-10 analogue) | Selank (tuftsin analogue — Thr-Lys-Pro-Arg-Pro-Gly-Pro) |
| Class | Synthetic neuropeptide — ACTH fragment | Synthetic heptapeptide — tuftsin analogue |
| Mechanism | Increases BDNF, stimulates serotonin/dopamine pathways, modulates ACTH-derived signalling, neuroprotective via HIF-1α pathway | Increases BDNF, modulates serotonin/GABA signalling, anxiolytic via tuftsin-related immune modulation, anti-stress |
| Half-life | ~7–10 minutes (intranasal); metabolised rapidly | ~1–2 minutes (IV); intranasal administration extends effective CNS exposure |
| Commonly reported doses | Commonly reported doses range from 300 to 600 mcg per dose intranasally; 25–100 mcg SubQ | Commonly reported doses range from 250 to 900 mcg per dose intranasally; or 250–500 mcg SubQ |
| Routes | Intranasal drops (most common), SubQ | Intranasal drops (most common), SubQ |
| Primary reported use | Cognitive enhancement, focus, memory, BDNF upregulation, neuroprotection | Anxiety reduction, stress resilience, mild cognitive enhancement, anti-fatigue |
Semax is described in anecdotal reports as stimulatory and focus-enhancing, with users reporting increased mental clarity, motivation, and verbal fluency. Selank is more often described as calming and anxiolytic, reducing background anxiety without sedation — sometimes compared to a mild GABAergic effect but without the same underlying mechanism.
Both compounds increase BDNF (brain-derived neurotrophic factor), a key driver of neuroplasticity and neuroprotection. This is a shared mechanism that places them in overlapping territory for long-term neuroprotective research, though the route to BDNF elevation differs between the two.
Both were developed in Russia and are approved there as pharmaceutical agents — Semax has been used clinically for stroke recovery. Outside Russia and the CIS they are research compounds. This approval history gives them a somewhat different evidence base compared to many peptides in the broader research community.
Semax is an ACTH 4-10 fragment that activates melanocortin receptors and modulates serotonin and dopamine synthesis. Research has investigated Semax for its potential role in BDNF and NGF upregulation, as well as neuroprotection via the HIF-1α pathway, which has been studied in the context of ischaemic conditions.
Selank is derived from tuftsin, a natural tetrapeptide, extended with a stabilising sequence. Research has investigated Selank for its potential role in enkephalin-modulating properties, serotonin transporter modulation, and a GABA-adjacent anxiolytic mechanism. Like Semax, it also upregulates BDNF, but the anxiolytic and anti-stress profile is the more distinctive feature studied in published literature.
Semax use cases in research and anecdotal accounts include cognitive enhancement, ADHD-adjacent focus improvement, post-stroke recovery (clinical use in Russia), and optic nerve research.
Selank use cases in research and anecdotal accounts include generalised anxiety, stress resilience, cognitive clarity under stress, and immune modulation.
For Semax, commonly reported doses range from 300 to 600 mcg intranasally, administered 1–2 times daily. SubQ injection at 25–100 mcg is also noted in anecdotal accounts.
For Selank, commonly reported doses range from 250 to 900 mcg intranasally, administered 1–3 times daily. SubQ injection at 250–500 mcg is also reported. Both compounds can be used at lower doses via injection compared to intranasal administration.
Intranasal administration is the most commonly reported route for both Semax and Selank. The nasal mucosa provides direct CNS access, which is considered advantageous given the short plasma half-lives of both peptides. SubQ injection is possible and is reported at lower doses, but intranasal is the more widely used method in both research and anecdotal protocols due to convenience and the CNS-targeting advantage.
Reported side effects in research and anecdotal accounts for Semax include mild headache, increased irritability at higher doses, and potential overstimulation.
Reported side effects in research and anecdotal accounts for Selank are generally minimal. Mild sedation at higher doses is occasionally noted. Overall, Selank is described as very well tolerated in both published studies and anecdotal accounts.
Semax is more commonly chosen in research contexts focused on cognitive performance, focus enhancement, BDNF upregulation, and acute neuroprotection. Selank is more commonly chosen when anxiety modulation, stress reduction, and calm cognitive clarity are the primary research variables. Both compounds are sometimes combined, with the complementary profiles cited as the rationale.
The combination of Semax and Selank is reported in both research literature and anecdotal communities. The pairing is described as potentially complementary: Semax provides the stimulatory cognitive enhancement while Selank provides anxiolytic modulation. Anecdotal reports suggest improvement in the tolerability of Semax at higher doses when Selank is co-administered, with the edginess or overstimulation sometimes associated with Semax alone reported as reduced. There is no dedicated stack page for this combination at this time.
Researchers commonly choose Semax when the primary focus is stimulatory cognitive enhancement, BDNF upregulation, or neuroprotection under acute conditions. Researchers commonly choose Selank when anxiety modulation, stress resilience, or calm cognitive enhancement is the key research variable. Where both properties are of interest, the combination is commonly reported as a protocol worth investigating.
Which is better for anxiety?
Selank has a stronger anxiolytic research profile of the two. Research has investigated Selank for its potential role in anxiety and stress reduction across multiple published studies. Semax is more stimulatory in character and may increase anxiety at higher doses in some individuals, based on anecdotal accounts.
Can Semax and Selank be used at the same time?
Yes, combination use is reported in both research and anecdotal communities. The complementary profiles — stimulatory (Semax) versus anxiolytic (Selank) — are the most commonly cited rationale for the combination.
Are Semax and Selank legal?
Both are research compounds outside Russia and the CIS. Legal status varies by jurisdiction and individuals should verify the regulations applicable in their location. In Russia, both are approved pharmaceutical agents with defined clinical uses.
Individual Compound Pages