Semax

A Russian-developed peptide nasal spray, approved there for stroke recovery and cognitive complaints, essentially unknown to Western regulators. One of the two Russian peptides (with Selank) that anchor the nootropic corner of this space.

Semax is a short synthetic peptide derived from a fragment of ACTH, the hormone that drives cortisol release — but the fragment was chosen specifically because it lacks the hormonal activity, leaving only the effects on the brain. The claimed mechanism is that it raises BDNF, a growth factor supporting neuron survival and plasticity, and modulates the brain's dopamine and serotonin systems. It is given as a nasal spray because a peptide this size would not survive digestion. The mechanism is plausible and is supported mainly by Russian laboratory work; the human clinical picture behind it does not meet the standards most readers would assume.

Russian clinical literature reports cognitive and neuroprotective effects, but it is largely untranslated, small-n, and from a research culture Western reviewers cannot easily audit. Mechanism (BDNF upregulation) is plausible and partly replicated in animals. Independent Western RCTs: effectively none. You are trusting a literature you cannot read.

• Semax is registered as a medicine in Russia. When FDA reviewed the available evidence in 2026 it found it INSUFFICIENT to establish effectiveness for the cerebral-ischaemia, migraine and neuralgia uses evaluated — the reports were small, lacked design detail, and did not establish benefit. It is not approved anywhere in the West.
• The trial literature is almost entirely Russian-language, largely predates modern reporting standards, and has not been independently replicated outside that research community.
• There are no Western randomised controlled trials of any size. That is the central fact, and it is not a matter of the evidence being new — the compound has existed since the 1980s.
• The BDNF story comes from rat hippocampus, not from people — FDA's review found no demonstrated human biomarker effect. It is a preclinical finding, full stop.
• There is no evidence for cognitive enhancement in healthy people, which is the use almost everyone buying it intends.

Given intranasally as drops. Human absorption, distribution and half-life have never been adequately characterised — FDA could not identify a human pharmacokinetic study by any route, so any half-life number in circulation is animal extrapolation. Almost everything sold in the West is grey-market research-chemical supply rather than the approved Russian pharmaceutical, meaning purity, concentration and sterility are unverified — and FDA's compounding review flagged impurity, endotoxin and nasal-delivery quality risks specifically.

Short-term tolerability looks benign in the reports that exist (nasal irritation). The honest risk is the unknown: no long-term human safety data outside Russia, and grey-market vials of a peptide with no Western pharmacopeia standard are a purity lottery.

• Anyone pregnant or breastfeeding
• Anyone with uncontrolled hypertension
• Anyone with a psychiatric condition, given the unclear effects on mood
• Anyone unwilling to accept that the product is unverified grey-market supply

• No characterised interaction profile exists in the Western literature, which reflects absence of study rather than absence of risk.
• Stimulants and other dopaminergic compounds, on mechanistic grounds rather than documented cases.
• Antidepressants, given the claimed serotonergic modulation.

• Safety cannot honestly be characterised — FDA found too little human data to describe its adverse reactions. That is different from being benign.
• Bleeding: FDA identified possible antithrombotic effects, which matters for anyone on anticoagulants or with a bleeding disorder.
• Blood pressure, since ACTH-fragment peptides have been reported to affect it.
• Mood and anxiety, which some users report shifting in both directions.
• What you actually bought — grey-market peptide supply is the dominant risk here, more than the molecule.

No withdrawal syndrome is described and none would be expected from a short peptide with brief exposure. Any claimed effects fade. Since no controlled evidence establishes a benefit in healthy people, there is nothing established to lose on stopping.

US: not approved, not scheduled — sold as "research" material. Prescription drug in Russia.

Papers about this compound, not proof of the claims above. A title says what was studied, which is sometimes a negative result or a different question entirely.

• The efficacy of semax in the tretament of patients at different stages of ischemic stroke
  Zh Nevrol Psikhiatr Im S S Korsakova, 2018
• ACTH administration during formation of preovulatory follicles impairs steroidogenesis and angiogenesis in association with ovulation failure in lactating cows
  Domest Anim Endocrinol, 2015
• Evaluation of therapeutic effect of new Russian drug semax in optic nerve disease
  Vestn Oftalmol, 2000

• Functional Connectomic Approach to Studying Selank and Semax EffectsDokl Biol Sci · 2020
• Semax peptide targets the μ opioid receptor gene Oprm1 to promote deubiquitination and functional recovery after spinal cord injury in female miceBr J Pharmacol · 2025
• Therapeutic Peptides in Orthopaedics: Applications, Challenges, and Future DirectionsJ Am Acad Orthop Surg Glob Res Rev · 2026
• Semax, synthetic ACTH(4-10) analogue, attenuates behavioural and neurochemical alterations following early-life fluvoxamine exposure in white ratsNeuropeptides · 2021
• Semax, a Synthetic Regulatory Peptide, Affects Copper-Induced Abeta Aggregation and Amyloid Formation in Artificial Membrane ModelsACS Chem Neurosci · 2022
• Semax, a Copper Chelator Peptide, Decreases the Cu(II)-Catalyzed ROS Production and Cytotoxicity of aβ by Metal Ion Stripping and Redox SilencingBioinorg Chem Appl · 2025
• Semax and Pro-Gly-Pro activate the transcription of neurotrophins and their receptor genes after cerebral ischemiaCell Mol Neurobiol · 2010
• Semax, an ACTH(4-10) analogue with nootropic properties, activates dopaminergic and serotoninergic brain systems in rodentsNeurochem Res · 2005
• The Potential of the Peptide Drug Semax and Its Derivative for Correcting Pathological Impairments in the Animal Model of Alzheimer's DiseaseActa Naturae · 2025
• Semax, an analog of ACTH((4-7)), regulates expression of immune response genes during ischemic brain injury in ratsMol Genet Genomics · 2017
• Semax, an analogue of adrenocorticotropin (4-10), binds specifically and increases levels of brain-derived neurotrophic factor protein in rat basal forebrainJ Neurochem · 2006
• Effects of Semax on the Default Mode Network of the BrainBull Exp Biol Med · 2018