Semax vs Cerebrolysin: differences, evidence and safety

Semax is a Russian nasal peptide linked to faster functional recovery in a 110-patient stroke study (Gusev 2018). Cerebrolysin is a pig-brain peptide mixture with placebo-controlled stroke trials (Cochrane 2023). Neither is FDA approved. Cerebrolysin has far more human evidence, but a Cochrane review found little to no effect on survival after stroke.

Item	Semax	Cerebrolysin
US FDA status	Not approved; no product in Drugs@FDA data (openFDA, searched 2026-11-08). A registered drug in Russia (FDA briefing)	Not approved; no product in Drugs@FDA data (openFDA, searched 2026-11-08). Used for stroke in Russia, Eastern Europe and China (Cochrane 2023)
Compounding (503A/503B)	Category 2 nomination withdrawn (FDA, updated 2026-04-22). PCAC voted 8–5 on 2026-07-24 to recommend 503A listing, as reported by trade press (FDA PCAC), after FDA staff proposed not listing it (FDA briefing); advisory, no FDA rule yet	Not on FDA’s Category 2 page (checked 2026-11-08); no PCAC review posted
WADA	Not named on the 2026 List; S0 covers substances with no government approval anywhere (WADA 2026). From 2027-01-01, S0 names “peptides” in general (USADA); status unclear	Not named on the 2026 List or in USADA’s 2027 advisory (checked 2026-11-08); status unclear, because it is approved in some countries
Strongest evidence	Human studies published in Russian (n=110 to 187)	Human RCTs and Cochrane reviews (up to n=1,070)
Human trials	0 registered (ClinicalTrials.gov, 2026-11-08)	43 registered (ClinicalTrials.gov, 2026-11-08)
Next regulatory step	None announced by FDA (checked 2026-11-08)	None announced
Last checked	2026-11-08	2026-11-08

Semax vs Cerebrolysin at a glance

Feature	Semax	Cerebrolysin
What it is	Synthetic heptapeptide, Met-Glu-His-Phe-Pro-Gly-Pro	Mixture of low-molecular-weight peptides and amino acids from pig brain
Class	ACTH(4-10) analog	Neuropeptide preparation
Main mechanism studied	Raises BDNF and trkB in rat hippocampus	Trophic, nerve-growth-like activity in cell culture
Main research focus	Stroke and cerebrovascular disease	Stroke recovery, brain injury, dementia
Human evidence	Russian studies, n=110 to 187	Placebo-controlled RCTs; 2 Cochrane reviews
Registered trials	0 (ClinicalTrials.gov)	43 (ClinicalTrials.gov)
US approval	None	None
Elsewhere	Registered drug in Russia	Approved for stroke in some countries
WADA	Not named; unclear	Not named; unclear
Routes studied	Intranasal	Intravenous infusion
Timelines in studies	BDNF stayed high over 5 months	Motor gains measured at day 90
Main safety concerns	No human pharmacokinetic data; FDA immunogenicity and bleeding concerns	More non-fatal serious adverse events after stroke

What is Semax?

Semax is a synthetic seven-amino-acid peptide, Met-Glu-His-Phe-Pro-Gly-Pro, built on a fragment of the hormone ACTH (adrenocorticotropic hormone) (Dolotov 2006). It is a registered drug in Russia, sold there as 0.1% and 1% nasal drops (FDA briefing document), and it is on Russia’s list of Vital and Essential Drugs (Radchenko 2025). FDA’s 2026 review found that its stroke studies are written in Russian (FDA briefing document). We compare it with its sister peptide on our Selank vs Semax comparison.

What is Cerebrolysin?

Cerebrolysin is a mixture of low-molecular-weight peptides and amino acids derived from pig brain, and it is widely used for acute ischemic stroke in Russia, Eastern Europe, China and other Asian countries (Cochrane 2023). A manufacturer-supported meta-analysis describes it as a neuropeptide preparation approved for the treatment of stroke (Guekht 2017). It is given as a series of daily intravenous infusions (Cochrane 2019). Unlike Semax, it has been tested in multinational placebo-controlled trials, several of them supported by its manufacturer.

How they work differently

• Semax: a single dose raised BDNF (brain-derived neurotrophic factor, a protein that supports nerve cells) 1.4-fold and its receptor trkB activation 1.6-fold in rat hippocampus, and treated rats learned an avoidance task better [Animal] (Dolotov 2006).
• Cerebrolysin: in rat PC12 cells, a lab model of nerve cells, it cut the share of dying cells from 32% to 10% and triggered growth of cell processes within 24 hours [Lab] (Safarova 2002).
• Semax: in the same cell test it had no such trophic effect, so the authors concluded its protective effects run through other mechanisms [Lab] (Safarova 2002).
• Cerebrolysin: because it is a mixture, no single receptor explains it; the Cochrane authors describe only “potential neuroprotective properties” (Cochrane 2023).

Evidence head-to-head: Semax vs Cerebrolysin

No study has compared Semax with Cerebrolysin in people (PubMed, searched 2026-11-08). The figures below come from separate studies, so any comparison between the columns is cross-trial.

Outcome	Semax best evidence	Cerebrolysin best evidence
Recovery after stroke	Human controlled, n=110: faster Barthel-index recovery and higher BDNF (Gusev 2018)	Human RCT meta-analysis, n=442: better arm function at day 90 (Guekht 2017)
Acute stroke outcome	Human controlled, 30 vs 80 patients: “some influence” on motor recovery speed (Gusev 1997)	Human RCT, n=1,070: no difference on the primary end point (Heiss 2012)
Death after stroke	No study found (PubMed, 2026-11-08)	Cochrane, 6 RCTs incl. one of Cortexin, n=1,689: RR 0.96, no difference (Cochrane 2023)
Cerebrovascular disease	Human, n=187: fewer strokes and transient attacks reported (Gusev 2005)	Cochrane, vascular dementia, n=420: SMD 0.36, very low quality (Cochrane 2019)
Brain injury	No study found (PubMed, 2026-11-08)	Human RCT meta-analysis, n=185: small-to-medium benefit at day 90 (Vester 2021)
Alzheimer’s disease	Animal: better memory tests, fewer amyloid deposits in mice (Radchenko 2025)	Human RCT meta-analysis, 6 trials: cognitive gain at 4 weeks, not at 6 months (Gauthier 2015)
Healthy people	Human reports, 33 to 47 healthy adults in total, mostly without safety data (FDA briefing)	Human RCT, n=48 healthy men: placebo’s early dip in word recall not seen (Funke 1998)

The most encouraging Cerebrolysin result is the CARS trial, where 21 days of infusions plus rehabilitation gave what its authors called a “large superiority” over placebo in arm function at day 90 [Human RCT] (Muresanu 2016). The authors called that trial exploratory and asked for a larger one. A 2021 European neurology guideline recommends Cerebrolysin for early rehabilitation after ischemic stroke (Beghi 2021). Semax’s strongest result is the 110-patient study, where treated patients recovered daily-living function faster [Human, controlled, n=110] (Gusev 2018). FDA reviewers set the Russian-language stroke papers aside because no English translations were available (FDA briefing document).

Which fits which goal?

• Stroke rehabilitation: Cerebrolysin has more evidence, from double-blind trials pooled across 442 patients (Guekht 2017). Semax has smaller Russian studies whose design is not fully described.
• Survival after stroke: neither has shown a benefit; Cochrane found Cerebrolysin made little to no difference to death (Cochrane 2023).
• Brain injury and dementia: Cerebrolysin has more evidence, though Cochrane rates the dementia data very low quality (Cochrane 2019). For Semax, the Alzheimer’s evidence found here comes from mice.
• Focus and memory in healthy people: neither has strong data. Cerebrolysin has one small 1998 trial in healthy men, and FDA counted only 33 to 47 healthy adults given Semax across published reports (FDA briefing document).
• ADHD: a 2026 Russian expert council put both in its “limited evidence base” group (Lapochkin 2026).

These are statements about evidence, not advice. A clinician is the person to decide whether either fits a given case.

Can Semax and Cerebrolysin be combined?

The two appear together in a 2002 cell-culture study, which tested each separately and found that only Cerebrolysin had a trophic effect [Lab] (Safarova 2002). A 2026 Russian expert council listed both as separate add-on options for ADHD but did not assess them together (Lapochkin 2026). No controlled human study of the combination was found on PubMed or ClinicalTrials.gov (searched 2026-11-08), so the safety of using both is unknown.

Safety and regulatory status

United States

Neither product is FDA approved; neither appears in Drugs@FDA data (openFDA, searched 2026-11-08). For Semax, FDA lists a possible immunogenicity risk, meaning unwanted immune reactions from aggregates and impurities (FDA Category 2 page). FDA staff found no human pharmacokinetic studies and one FAERS report, from a consumer hospitalized with eye pain after nasal drops bought online (FDA briefing document). The same review flags possible bleeding risk and, in mice, a boost to amphetamine-driven dopamine release. Staff proposed keeping Semax off the 503A list; the advisory committee then voted 8–5 for listing, as reported by trade press (FDA PCAC). Our guide to the FDA compounding vote explains what that does and does not change.

Side effects in studies

For Cerebrolysin after stroke, Cochrane found more people with non-fatal serious adverse events (RR 2.39, 95% CI 1.10 to 5.23; 3 trials, 1,335 people), with no difference in total serious events (Cochrane 2023). In healthy men, the highest dose caused mild overdose signs and a small fall in blood pressure (Funke 1998). For Semax, a Russian study of 73 patients recorded episodes of paroxysmal (sudden-burst) EEG activity in some cases after Semax injection (Alekseeva 1999).

Sport

Neither is named on the WADA 2026 List. Its S0 class covers substances with no approval by any government health authority (WADA 2026). Both have approval somewhere, so the wording does not settle their status. A 2025 anti-doping review rated Semax “unclear”, noting its likeness to tetracosactide, a prohibited S2 hormone (Biology of Sport 2025). From 2027-01-01, S0 names “peptides” in general, and USADA warns that an unnamed peptide “may still be prohibited” (USADA). USADA explains the non-approved class in its #AskUSADA guide.

Anyone who suspects a side effect from Semax, Cerebrolysin or any other drug or product can report it to the FDA through MedWatch.

How long do effects take in studies?

• Semax: after stroke, plasma BDNF rose quickly and stayed high across the 5-month observation (Gusev 2018).
• Cerebrolysin, stroke: early neurological gains were measurable at days 14 and 21, and arm-function gains at day 90 (Guekht 2017).
• Cerebrolysin, healthy men: brain-wave changes began 15 minutes after an infusion, peaked at 2 hours and lasted to 8 hours (Funke 1998).
• Cerebrolysin, Alzheimer’s: the cognitive gain seen at 4 weeks was no longer statistically significant at 6 months (p = 0.1710) (Gauthier 2015).