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Comparison

Dihexa vs Semax

Both are nootropic & neuro, so the meaningful differences are in kinetics, evidence and regulatory status.

On published evidence alone, Semax is the better documented of the two (preliminary human). That is a statement about the state of the literature, not a recommendation.

Dihexa Semax
Class Nootropic & neuro Nootropic & neuro
Evidence Animal models only Preliminary human
Human trials None published ~8
Half-life ~10-12 hours ~30 minutes (intranasal)
Reported range 8-45 mg 300-900 mcg
Frequency Once daily 1-3x daily intranasal
Routes Oral, Subcutaneous, Topical Intranasal, Subcutaneous
FDA approved No No
Research use only Yes Yes
Banned in sport No No
Studied for Cognitive research, Neurodegeneration research Cognitive enhancement research, Stroke recovery, Optic nerve conditions
Reported side effects Headache, Overstimulation, Poorly characterised Nasal irritation, Headache, Overstimulation, Irritability

Dihexa

Dihexa is a small peptidomimetic derived from angiotensin IV, engineered for blood-brain barrier penetration. It is understood to potentiate hepatocyte growth factor signalling at the c-Met receptor, driving synaptogenesis and dendritic spine formation. The often-quoted figure describing it as seven orders of magnitude more potent than BDNF comes from an in vitro assay in a rodent model, not from human data, and no human trial has been published.

Semax

Semax is an analog of adrenocorticotropic hormone fragment 4-10, extended with proline-glycine-proline to resist enzymatic degradation. The modification removes hormonal activity at the adrenal cortex while preserving central effects, which include increased expression of brain-derived neurotrophic factor and its receptor TrkB, and modulation of dopaminergic and serotonergic transmission. It is on the Russian essential medicines list for stroke and cognitive disorders.

Dihexa vs Semax: common questions

What is the difference between Dihexa and Semax?

Both are nootropic & neuro. Dihexa: An angiotensin IV derivative reported in animal work to be dramatically more potent than BDNF at promoting synaptogenesis. Semax: A heptapeptide ACTH fragment analog used in Russia for stroke and cognitive indications, with no corticotropic activity.

Which has stronger evidence, Dihexa or Semax?

Semax has the stronger evidence base (preliminary human, about 8 human studies) compared with Dihexa (animal models only).

Are Dihexa and Semax FDA approved?

Neither is FDA approved for any indication.

References

Regulatory and primary sources

  1. PubChem compound record (CID 129010512) ↗ · structure, identifiers, synonyms
  2. FDA: Unapproved drugs and "research use only" products ↗ · regulatory status of non-approved products
  3. PubChem compound record (CID 9811102) ↗ · structure, identifiers, synonyms
  4. CAS Registry Number 80714-61-0 ↗ · chemical identity

Published literature

  1. Rahman OF, Lee SJ, Seeds WA. Therapeutic Peptides in Orthopaedics: Applications, Challenges, and Future Directions.J Am Acad Orthop Surg Glob Res Rev 2026.PubMed 41490200 · doi:10.5435/JAAOSGlobal-D-25-00236
  2. Wright JW, Harding JW. The Brain Hepatocyte Growth Factor/c-Met Receptor System: A New Target for the Treatment of Alzheimer's Disease.J Alzheimers Dis 2015.PubMed 25649658 · doi:10.3233/JAD-142814
  3. Ho JK, Nation DA. Cognitive benefits of angiotensin IV and angiotensin-(1-7): A systematic review of experimental studies.Neurosci Biobehav Rev 2018.PubMed 29733881 · doi:10.1016/j.neubiorev.2018.05.005
  4. Wright JW, Kawas LH, Harding JW. The development of small molecule angiotensin IV analogs to treat Alzheimer's and Parkinson's diseases.Prog Neurobiol 2015.PubMed 25455861 · doi:10.1016/j.pneurobio.2014.11.004
  5. Tarasov VV, Kudryashov NV, Chubarev VN, et al.. Pharmacological Aspects of Neuro-Immune Interactions.Curr Pharm Des 2018.PubMed 28875850 · doi:10.2174/1381612823666170829135115
  6. Ilina AR, Popovich IG, Ryzhak GA, et al.. [Prospects for use of short peptides in pharmacotherapeutic correction of Alzheimer's disease.].Adv Gerontol 2024.PubMed 38944767
  7. Sudakov KV. [Evolution of the stress concept].Vestn Ross Akad Med Nauk 2008.PubMed 19140465
  8. Gusev EI, Martynov MY, Kostenko EV, et al.. [The efficacy of semax in the tretament of patients at different stages of ischemic stroke].Zh Nevrol Psikhiatr Im S S Korsakova 2018.PubMed 29798983 · doi:10.17116/jnevro20181183261-68
  9. Vyunova TV, Medvedeva EV, Andreeva LA, et al.. [POSSIBLE ROLE OF TRANSTHYRETIN IN THE BIOLOGICAL MECHANISM OF THE REGULATORY PEPTIDE NEUROPROTECTION.].Mol Gen Mikrobiol Virusol 2016.PubMed 30383932
  10. Giri S, Chandra P. Modulation of neuropathological pathways by bioactive peptides and proteins/polypeptides: Targeting oxidative stress in neurodegenerative diseases.Neuropeptides 2025.PubMed 41004910 · doi:10.1016/j.npep.2025.102563
  11. Spirin NN, Fedorov VN, Vdovichenko VP. [Place of oligopeptide H-Met-Glu-His-Phe-Pro-Gly-Pro-OH in the therapy and rehabilitation of patients with ischemic stroke].Zh Nevrol Psikhiatr Im S S Korsakova 2024.PubMed 39166935 · doi:10.17116/jnevro202412408256

Literature retrieved from PubMed on October 16, 2026, favouring human studies and reviews. Numbered markers in the text show which paper supports which statement; uncited entries are background reading.

Read this first This page compares published reference data. It is not medical advice and not a recommendation to use either compound. Several compounds documented on this site are not approved for human use.