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Semax for Cognition: What the Evidence Shows

What human and animal studies show about Semax for cognition, how strong that evidence is, and what is still unproven.

Medical review pendingACTH(4-10) analogUpdated
Strongest evidence
Human RCT
Human studies
13
PubMed records, our ledger
Animal studies
53
PubMed records, our ledger
Studies we summarised
8
with an outcome for cognition

Evidence for cognition

Each row is an outcome related to cognition from a published study, strongest design first. Animal and cell results are labelled and are not human results. User reports are not counted as evidence here.

Semax for cognition: outcomes in published studies
OutcomeResultStudy typeSource
Plasma BDNFSemax raised plasma BDNF levels, which stayed high through the study.Human controlled trialn = 110Zhurnal nevrologii i psikhiatrii imeni S.S. Korsakova 2018, PMID 29798983
Functional recovery (Barthel index)Semax and high BDNF were associated with faster improvement and a better final Barthel score.Human controlled trialn = 110Zhurnal nevrologii i psikhiatrii imeni S.S. Korsakova 2018, PMID 29798983
Default mode networkSemax group showed a greater volume of the rostral default mode network subcomponent on fMRI than placebo; no behavioural outcome was reported.Human controlled trialn = 24Bulletin of experimental biology and medicine 2018, PMID 30225715
Memory disordersTherapy was effective in patients with memory (mnestic) disorders.Human uncontrolled trialn = 73Anesteziologiia i reanimatologiia 1999, PMID 10199046
Motor activity and behaviourSemax did not change motor activity or passive defensive behaviour in this model.Animal · rat (not a human result)Doklady biological sciences 2017, PMID 28702721
Long-term effects of early-life stressChronic intranasal semax reduced the long-lasting negative effects of neonatal isolation stress.Animal · rat (not a human result)Acta naturae 2012, PMID 22708068
Learning by routeIntranasal semax improved learning more potently than intraperitoneal dosing in rats.Animal · rat (not a human result)Rossiiskii fiziologicheskii zhurnal imeni I.M. Sechenova 2010, PMID 21268834
Infarct volume and memorySix days of intranasal semax reduced cortical infarct volume and improved avoidance retention.Animal · rat (not a human result)Bulletin of experimental biology and medicine 2006, PMID 17603664
Behavioural disturbances after MPTPDaily intranasal semax (0.2 mg/kg) lessened MPTP-induced behavioural disturbances, which included reduced movement and increased anxiety.Animal · rat (not a human result)Neuroscience and behavioral physiology 2004, PMID 15341218

PubMed records for Semax and cognition: 13 human, 53 animal (search counts, not studies we reviewed). Grades follow our .

How strong is it?

Strongest evidence:Human RCT evidence, 4 of 4Zhurnal nevrologii i psikhiatrii imeni S.S. Korsakova 2018, PMID 29798983

A human randomized trial outweighs any number of animal studies. Animal and cell results show a mechanism worth testing, not that it works in people.

What memory is

In the MedlinePlus summary, memory is the process of storing information and then remembering it, which is the ability the semax studies below are measured against.[9]

Human semax data nearest to cognition

In patients with posthypoxic encephalopathy, the therapy was effective in patients with mnestic (memory) disorders, per the abstract.[3]

Resting-state fMRI in healthy volunteers measured the effect of intranasal semax on brain networks, not a memory or attention score.[2]

The semax group had a greater volume of the default mode network's rostral subcomponent than controls on the later scans.[2]

After ischemic stroke, semax increased plasma BDNF levels that stayed high during the study; the outcomes were BDNF, motor performance and Barthel score, not cognition tests.[1]

The goal ledger (PubMed, run 2 Oct 2026) counts 13 human-only and 53 animal papers for semax with brain-health terms, and 0 carry a randomized-trial tag.

Calculated from pubmed query (semax[tiab]) AND (cogniti*[tiab] OR neuroprotect*[tiab] OR "brain function"[tiab] OR "brain health"[tiab] OR memory[tiab] OR "cerebral ischemia"[tiab] OR "ischemic stroke"[tiab] OR "brain injury"[tiab] OR neurodegenerat*[tiab] OR dementia[tiab]); date 2026-10-02; human only count 13; animal filter count 53; randomized filter count 0. Formula: counts as recorded in the goals.json ledger

Animal findings on learning and memory

In rats with a light-induced prefrontal infarct, 6 days of intranasal semax decreased infarct volume and improved retention of a passive avoidance response.[7]

In white rats, intranasal semax was more potent for learning than intraperitoneal semax, while only the intraperitoneal route changed pain sensitivity.[6]

Rat pups isolated early in life received intranasal semax at 50 µg/kg daily and showed less of the long-lasting stress effects; this is rat data.[5]

In rats with toxin-induced parkinsonism, semax and selank did not affect motor activity; semax is not reported to help there.[4]

Other peptides people research for cognition

TirzepatideSemaglutideBPC-157SelankDihexa

Common questions

Does Semax help with cognition?

The strongest study we summarise for cognition is human rct evidence, across 8 studies with an outcome for cognition. A trial result is not an approval; see the legal status.

Is Semax approved for cognition?

No. Semax is not FDA approved for any use, including cognition.

Does semax improve memory?

In rats with induced cortical infarction, intranasal semax improved retention and performance of a passive avoidance response; no human memory test result is in the cached abstracts.[7]

Is semax a nootropic?

Semax is called a nootropic drug in the fMRI paper, which measured network topography after intranasal dosing rather than a cognitive benefit.[2]

More on Semax

DosageDoses used in published studies, with the source for each.CalculatorVial, water and dose to syringe units.Side effectsWhat labels and studies report, and what is unknown.BenefitsClaimed benefits next to what published studies measured.How it worksTarget, mechanism and how long it acts, from the label or studies.Nasal sprayStudies that gave Semax as nasal spray, and what is approved.

Sources

  1. 1[The efficacy of semax in the tretament of patients at different stages of ischemic stroke].Zhurnal nevrologii i psikhiatrii imeni S.S. Korsakova · 2018PMID 29798983Accessed 2 Oct 2026
  2. 2Effects of Semax on the Default Mode Network of the Brain.Bulletin of experimental biology and medicine · 2018PMID 30225715Accessed 2 Oct 2026
  3. 3[Use of semax at a follow-up of patients with posthypoxic encephalopathy].Anesteziologiia i reanimatologiia · 1999PMID 10199046Accessed 2 Oct 2026
  4. 4Peptides semax and selank affect the behavior of rats with 6-OHDA induced PD-like parkinsonism.Doklady biological sciences : proceedings of the Academy of Sciences of the USSR, Biological sciences sections · 2017PMID 28702721Accessed 2 Oct 2026
  5. 5Correction of long-lasting negative effects of neonatal isolation in white rats using semax.Acta naturae · 2012PMID 22708068Accessed 2 Oct 2026
  6. 6[Nootropic and analgesic effects of Semax following different routes of administration].Rossiiskii fiziologicheskii zhurnal imeni I.M. Sechenova · 2010PMID 21268834Accessed 2 Oct 2026
  7. 7Neuroprotective and antiamnesic effects of Semax during experimental ischemic infarction of the cerebral cortex.Bulletin of experimental biology and medicine · 2006PMID 17603664Accessed 2 Oct 2026
  8. 8The neuroprotective effects of Semax in conditions of MPTP-induced lesions of the brain dopaminergic system.Neuroscience and behavioral physiology · 2004PMID 15341218Accessed 2 Oct 2026
  9. 9Official web pageOfficial web page · web page

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