Cortexin vs Semax
Bovine cerebral cortex-derived polypeptide preparation with nootropic, neuroprotective, and antioxidant properties used clinically in Russia for cerebrovascular disorders, cognitive impairment, and pediatric neurology
A brain-boosting peptide that supercharges your cognitive function by ramping up BDNF—the protein your neurons need to grow, connect, and stay sharp—all delivered through a simple nasal spray.
Written by Michael Carroll — Owner, Director of Research · Reviewed by the Peptide Initiative Research Team · Editorial standards
Quick comparison
Dose range
Cortexin
10–10 mg
Semax
500–900 mcg/day
Frequency
Cortexin
Once daily
Semax
Once daily
Administration
Cortexin
Intramuscular (IM) injection
Semax
Intranasal spray
Cycle length
Cortexin
8-12 weeks
Semax
4-6 weeks
Onset speed
Cortexin
Moderate (1-2 weeks)
Semax
Rapid (hours to days)
Evidence level
Cortexin
Limited human trials
Semax
Moderate human trials (Phase 1-2)
Benefit ratings
Brain Recovery
Cognitive Function
Neuroprotection
Cognitive Enhancement
Mental Energy
Compound specifications
Cortexin
Molecular formula
Complex mixture — no single molecular formula (contains multiple low molecular weight polypeptide fractions, L-amino acids, vitamins, and trace elements)
Molecular weight
Low molecular weight water-soluble polypeptide fractions — specific molecular weight distribution varies as a complex biological mixture
Half-life
Approximately 2-6 hours (varies by route of administration)
Bioavailability
~85-100% (intramuscular injection)
CAS number
Not assigned (biological mixture)
Semax
Molecular formula
C37H51N9O10S
Molecular weight
813.9 g/mol
Half-life
Several minutes to hours (intranasal effects persist longer)
Bioavailability
High via intranasal route (directly reaches brain)
CAS number
80714-61-0
Dosing compared
Cortexin
Intramuscular
10 mg
Once daily · 10 days per course; repeat in 3-6 months if needed
The standard adult dose per the manufacturer instructions. The 10 mg vial is dissolved in 1-2 mL of saline, water for injection, or 0.5% procaine and injected into a muscle. Children under 20 kg get 0.5 mg/kg. [6]
Semax
Intranasal
250-500 mcg/day
Once or twice daily · 1-2 weeks
Cognitive/nootropic practice with the 0.1% solution; downstream BDNF/NGF effects persist 12-24 h so dosing is once to twice daily [1][2].
500-900 mcg/day
Divided 2-3 times daily · 3-4 weeks
Mid-range nootropic practice dose; upregulates hippocampal BDNF/TrkB in animal models [1][2][3].
Best suited for
Cortexin
Cognitive support in chronic cerebral ischemia and cerebrovascular disease
Cortexin is particularly well-suited for individuals focused on cognitive support in chronic cerebral ischemia and cerebrovascular disease. Research and clinical experience suggest meaningful benefits in this area when used as part of a comprehensive treatment approach [5].
Neuroprotection and neurorecovery following stroke or traumatic brain injury
Cortexin is particularly well-suited for individuals focused on neuroprotection and neurorecovery following stroke or traumatic brain injury. Research and clinical experience suggest meaningful benefits in this area when used as part of a comprehensive treatment approach [7].
Pediatric neurology including cerebral palsy and developmental delays
Cortexin is particularly well-suited for individuals focused on pediatric neurology including cerebral palsy and developmental delays. Research and clinical experience suggest meaningful benefits in this area when used as part of a comprehensive treatment approach [7][8].
Adjunctive treatment in epilepsy management
Cortexin is particularly well-suited for individuals focused on adjunctive treatment in epilepsy management. Research and clinical experience suggest meaningful benefits in this area when used as part of a comprehensive treatment approach [7][8].
Semax
Students and Knowledge Workers
If your day revolves around learning, studying, or processing complex information, Semax can be a game-changer. It enhances memory consolidation and recall while improving your ability to focus for extended periods—perfect for exam prep or demanding projects [6][12].
Those Seeking Mental Clarity
Brain fog? Semax works by boosting BDNF—the protein that helps neurons communicate effectively. [1][2] Users often report feeling like the 'mental static' clears away, leaving sharper, more efficient thinking in its place.
Neuroprotection Seekers
Beyond immediate cognitive benefits, Semax offers protective effects for your brain cells. [9] It acts as an antioxidant (especially against copper toxicity) [4][8] and supports neuronal health—valuable for anyone concerned about long-term brain wellness.
Recovery Support (Under Medical Supervision)
In Russia, Semax is approved for helping stroke patients and those with traumatic brain injuries recover cognitive function. [6] While not FDA-approved for this use elsewhere, the research shows meaningful neuroprotective and neurorestorative properties [7][9].
Side effects
Cortexin
Common
- Injection site reactions
- Headache
- Dizziness
- Nausea
- Agitation or restlessness
- Transient blood pressure changes
Uncommon
- Allergic reactions
Serious
- Severe allergic reaction / Anaphylaxis
Semax
Common
- Nasal irritation
- Mild headache
- Increased alertness
Uncommon
- Temporary blood pressure increase
- Dizziness
Serious
- Allergic reaction
Safety & evidence
Cortexin
Evidence level
Limited human trials
FDA status
Research compound
Safety overview
Cortexin is a porcine brain-derived polypeptide preparation used in Russian neurology that is not FDA-approved and has no Western rigorous safety data. As an undefined mixture of peptides and proteins extracted from animal brains, batch standardization and quality control are not guaranteed. Concerns include potential transmissible spongiform encephalopathy (TSE/prion) risk from animal CNS tissue, although documented cases have not been reported. Allergic reactions to porcine proteins are possible. No formal human safety assessments, toxicology studies, or clinical trials by modern regulatory standards have been conducted. Use in Western countries is essentially non-existent due to regulatory limitations on animal-derived neurological products.
Contraindications
- Known hypersensitivity to Cortexin or any component including glycine stabilizer
- Allergy to bovine-derived biological products
- Pregnancy — insufficient safety data for use during pregnancy
- Breastfeeding — insufficient data on excretion into breast milk
Semax
Evidence level
Moderate human trials (Phase 1-2)
FDA status
Research compound
Safety overview
Semax has been used clinically in Russia for over 25 years with an excellent safety profile. [7][12] It's approved there for treating stroke, cognitive impairment, and optic nerve diseases. [6] Studies consistently show minimal side effects, mostly limited to mild nasal irritation when using the spray form. [6][9] Unlike stimulants, Semax doesn't appear to cause tolerance, dependence, or withdrawal symptoms even with extended use.
Contraindications
- Pregnancy or planning to become pregnant
- Currently breastfeeding
- History of seizures or epilepsy
- Known allergy to ACTH-related peptides
- Uncontrolled hypertension
Which is right for you?
Choose Cortexin if...
- Cognitive support in chronic cerebral ischemia and cerebrovascular disease
- Neuroprotection and neurorecovery following stroke or traumatic brain injury
- Pediatric neurology including cerebral palsy and developmental delays
- Adjunctive treatment in epilepsy management
Choose Semax if...
- Cognitive enhancement
- Memory improvement
- Focus and concentration
- Neuroprotection