Semax
A lab-made peptide based on a brain hormone fragment. Developed in Russia and approved there for cognitive problems and brain injury recovery. Helps with thinking, memory, and sustained focus by boosting brain-nourishing factors in memory and learning areas.
Semax is a synthetic heptapeptide derived from the first four amino acids of adrenocorticotropic hormone (ACTH 4-7) with an added Pro-Gly-Pro C-terminal tripeptide that improves stability and bioavailability. Developed at the Institute of Molecular Genetics of the Russian Academy of Sciences, it is approved in Russia and several CIS countries as a prescription medication for cerebrovascular conditions, cognitive enhancement, and neuroprotection.
Semax works through multiple neurological pathways. It enhances brain-derived neurotrophic factor (BDNF) expression — the key protein responsible for neuronal growth, survival, and plasticity. It modulates dopamine and serotonin metabolism, supports the cholinergic system involved in memory formation, and has demonstrated neuroprotective effects against oxidative stress and ischemic damage. These combined effects make it relevant for both acute neurological events (stroke, TBI) and chronic cognitive enhancement.
Semax is administered intranasally at 200-600 mcg per dose, 2-3 times daily. The intranasal route allows it to bypass the blood-brain barrier to some degree, providing more direct central nervous system effects. A higher-concentration formulation (1%) is available for acute neurological applications. While safety data from Russian clinical use suggests good tolerability, Western clinical validation remains limited.
Dosage
Intranasal: 200-600 mcg 2-3x daily
Dosages shown are for research reference only. Always consult a qualified healthcare provider.
Administration
Intranasal spray (primary) or subcutaneous injection
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Effects
Cognitive Enhancement
BDNF and NGF upregulation enhances memory, attention, and executive function.
Neuroprotection
Approved in Russia for stroke recovery and TBI — reduces glutamate excitotoxicity.
Focus & Attention
Enhances noradrenergic signaling from locus coeruleus for improved alertness.
Mechanism of Action
Semax is a synthetic heptapeptide consisting of the ACTH(4-10) fragment (Met-Glu-His-Phe-Pro-Gly-Pro) — the shortest sequence of ACTH that retains neurotrophic activity — with a Pro-Gly-Pro C-terminal extension for proteolytic stability. Crucially, it contains only the neurotrophic portion of ACTH without the N-terminal amino acids (residues 1-3) required for adrenal cortex stimulation, so it has no effect on cortisol production or the HPA stress axis.
Semax's primary nootropic mechanism is upregulation of neurotrophic factors in the hippocampus and cortex. It increases expression of brain-derived neurotrophic factor (BDNF) — the most important neurotrophin for learning and memory — through activation of the TrkB receptor signaling cascade (Ras/MAPK and PI3K/Akt pathways). BDNF promotes dendritic spine formation, enhances long-term potentiation (the cellular basis of memory), and supports neuronal survival. Semax also upregulates nerve growth factor (NGF), which maintains cholinergic neurons in the basal forebrain — the same neurons that degenerate in Alzheimer's disease and are critical for attention and memory.
At the neurotransmitter level, Semax modulates three monoamine systems. It enhances dopaminergic transmission in the prefrontal cortex and striatum, improving motivation, reward processing, and executive function. It modulates serotonergic activity (5-HT) in the raphe nuclei and limbic system, affecting mood and emotional regulation. It also enhances noradrenergic signaling from the locus coeruleus, improving alertness, focused attention, and working memory. The noradrenergic effect may be particularly relevant for its clinical use in ADHD-like conditions and attention disorders. In stroke recovery (an approved indication in Russia), Semax provides neuroprotection through multiple mechanisms: BDNF-mediated anti-apoptotic signaling, reduction of glutamate excitotoxicity, decreased oxidative stress, and maintenance of blood-brain barrier integrity in the peri-infarct region.
Regulatory Status
Approved in Russia and Ukraine for cognitive disorders, stroke recovery, and ADHD. Not FDA approved. Available through international peptide suppliers.
Risks & Safety
Common
mild irritability, trouble sleeping at higher doses, nasal irritation (when used as nose spray).
Serious
anecdotal reports of hair thinning, most evidence comes from Russian clinical studies with limited Western validation.
Rare
allergic reactions, significant overstimulation.
Compare Semax With
Research Papers
20Published: December 31, 2025
AI Summary
Peptides such as Semax and others show promise for tissue repair, inflammation, and recovery in orthopaedics, but clinical trials are still lacking. The review covers pathways and mechanisms of action.
Published: September 2, 2025
AI Summary
In mice with Alzheimer's-like changes, Semax and a related compound improved both memory and amyloid buildup in the brain. The results suggest these peptides may help develop new treatment strategies for the disease.
Published: September 21, 2023
AI Summary
A study in rats with spinal cord injury showed that Semax modulates levels of anti-inflammatory cytokines IL-4, IL-10, and IL-13. The findings suggest a role for Semax in tempering inflammation after spinal cord trauma.
Published: August 30, 2025
AI Summary
Semax altered calcium signaling in hippocampus neurons but not in cerebellar cells. This suggests its main neuroprotective effects likely stem from actions in the hippocampus rather than from acid-sensing ion channels in the cerebellum.
Published: December 20, 2025
AI Summary
Semax and related peptides are among the agents that can modulate oxidative stress and neurodegeneration. The review discusses mechanisms and prospects for treating conditions such as Alzheimer's and Parkinson's disease.
Published: November 20, 2025
AI Summary
Semax appears to promote recovery after spinal cord injury by affecting the opioid receptor gene and deubiquitination. These findings suggest a potential mechanism for its neuroprotective effects in female mice.
Published: June 27, 2025
AI Summary
ACTH-like peptides influenced gene expression differently in brain areas with varying levels of ischemia. The results suggest tailored peptide selection could improve neuroprotection after stroke.
Published: June 2, 2025
AI Summary
Semax protects cells by binding copper and reducing the harmful oxidative stress triggered by amyloid beta. The work suggests a potential mechanism for limiting damage in Alzheimer's disease.
Published: December 12, 2024
AI Summary
One day after stroke in rats, Semax and a related peptide restored many gene expression changes caused by ischemia. The findings support the idea that these peptides can help the brain recover after stroke.
Published: December 4, 2024
AI Summary
Semax and Melanotan II reduced anhedonia and stress-related changes in chronically stressed rats. The results support the possibility that ACTH-like peptides could help treat depression and stress-related disorders.
Published: September 17, 2024
AI Summary
Under normal conditions, Semax and a related peptide altered gene expression in distinct ways, with both reducing immune-related genes. The results highlight how small structural differences affect brain transcriptome patterns.
Published: June 29, 2023
AI Summary
Semax and related peptides partly reversed stroke-induced changes in immune and signaling genes in the early hours after stroke. The study supports their use in early post-stroke therapy.
Published: June 5, 2023
AI Summary
Semax and related peptides modulated GABA receptor binding in rat brain, but their effects differed from those of acute stress. The work clarifies how these peptides interact with the inhibitory neurotransmitter system.
Published: December 15, 2022
AI Summary
Compared with Semax, PGP and PGPL peptides showed distinct effects on inflammation and signaling genes after stroke. The study clarifies how different glyproline peptides affect the brain after ischemia.
Published: February 15, 2022
AI Summary
Semax reduced the formation of amyloid aggregates when copper was present, both in solution and on membranes. The findings suggest a potential route for limiting amyloid formation in Alzheimer's disease.
Published: April 19, 2021
AI Summary
When given before a toxin, Semax modestly preserved dopamine in the striatum, suggesting it acts mainly by boosting neurotrophic factors rather than as an antioxidant. The model supports the use of Semax for testing neuroprotective drugs.
Published: September 16, 2021
AI Summary
Semax and a related peptide reversed stress-induced changes in behavior and gene expression in the hippocampus. The results suggest they help restore normal gene expression patterns disrupted by acute stress.
Published: August 21, 2021
AI Summary
The neuropeptide Y-derived peptide NP9 outperformed Semax in memory and behavior tests, suggesting it may be useful for cognitive impairment and PTSD. The study used Semax as a reference for comparison.
Published: June 7, 2021
AI Summary
Semax reduced the expression of inflammatory and cell-death proteins while promoting recovery-related proteins in the brain after stroke. The protein data confirm the peptide's neuroprotective effect at the molecular level.
Published: July 28, 2021
AI Summary
Semax lowered the expression of several proinflammatory genes that were increased after stroke in rats. The findings suggest that its neuroprotective effect may stem partly from its anti-inflammatory actions.
Frequently Asked Questions
What is Semax?
A lab-made peptide based on a brain hormone fragment. Developed in Russia and approved there for cognitive problems and brain injury recovery. Helps with thinking, memory, and sustained focus by boosting brain-nourishing factors in memory and learning areas.
What is Semax used for?
A lab-made peptide based on a brain hormone fragment. Developed in Russia and approved there for cognitive problems and brain injury recovery. Helps with thinking, memory, and sustained focus by boosting brain-nourishing factors in memory and learning areas.
What is the dosage for Semax?
Intranasal: 200-600 mcg per dose, two or three times daily. Typical cycle: 10-14 days on, equal time off. Higher concentration (1%) available for acute neurological applications and TBI recovery.
What are the side effects of Semax?
Common: mild irritability, trouble sleeping at higher doses, nasal irritation (when used as nose spray). Serious: anecdotal reports of hair thinning, most evidence comes from Russian clinical studies with limited Western validation. Rare: allergic reactions, significant overstimulation.
How does Semax work?
Semax is a synthetic heptapeptide consisting of the ACTH(4-10) fragment (Met-Glu-His-Phe-Pro-Gly-Pro) — the shortest sequence of ACTH that retains neurotrophic activity — with a Pro-Gly-Pro C-terminal extension for proteolytic stability. Crucially, it contains only the neurotrophic portion of ACTH without the N-terminal amino acids (residues 1-3) required for adrenal cortex stimulation, so it has no effect on cortisol production or the HPA stress axis. Semax's primary nootropic mechanism is upregulation of neurotrophic factors in the hippocampus and cortex. It increases expression of brain-derived neurotrophic factor (BDNF) — the most important neurotrophin for learning and memory — through activation of the TrkB receptor signaling cascade (Ras/MAPK and PI3K/Akt pathways). BDNF promotes dendritic spine formation, enhances long-term potentiation (the cellular basis of memory), and supports neuronal survival. Semax also upregulates nerve growth factor (NGF), which maintains cholinergic neurons in the basal forebrain — the same neurons that degenerate in Alzheimer's disease and are critical for attention and memory. At the neurotransmitter level, Semax modulates three monoamine systems. It enhances dopaminergic transmission in the prefrontal cortex and striatum, improving motivation, reward processing, and executive function. It modulates serotonergic activity (5-HT) in the raphe nuclei and limbic system, affecting mood and emotional regulation. It also enhances noradrenergic signaling from the locus coeruleus, improving alertness, focused attention, and working memory. The noradrenergic effect may be particularly relevant for its clinical use in ADHD-like conditions and attention disorders. In stroke recovery (an approved indication in Russia), Semax provides neuroprotection through multiple mechanisms: BDNF-mediated anti-apoptotic signaling, reduction of glutamate excitotoxicity, decreased oxidative stress, and maintenance of blood-brain barrier integrity in the peri-infarct region.
How is Semax administered?
Semax is administered via intranasal spray (primary) or subcutaneous injection.
What is the half-life of Semax?
The half-life of Semax is 2-3 minutes (rapidly metabolized, but CNS effects persist for hours).
Is Semax legal?
Approved in Russia and Ukraine for cognitive disorders, stroke recovery, and ADHD. Not FDA approved. Available through international peptide suppliers.
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