Semax Side Effects: What the Research Reports
Cognitive & Nootropic Research
In a clinical study of 187 patients with cerebrovascular insufficiency, Semax was well tolerated, including by older patients, and side effects were reported in only a small percentage (Gusev et al., Zh Nevrol Psikhiatr, 2005). Its developers, summarising 15 years of work, reported that across its clinical use it produced no negative side actions or complications connected with its administration (Ashmarin et al., 1997). This page sets out what the human studies recorded, where Semax comes from, and why it lacks the hormonal effects of the hormone it is based on. Semax is also supplied as a ready-mixed Semax Nasal Spray.
Findings
- In 187 patients with different stages of cerebrovascular insufficiency, Semax was well tolerated with a minor percentage of side effects, including in older age groups, alongside clinical improvement (Gusev et al., 2005).
- Its developers reported that in clinical use no negative side actions or complications were connected with Semax (Ashmarin et al., Zh Vyssh Nerv Deiat, 1997).
- In 110 patients recovering from ischemic stroke, Semax raised plasma BDNF, a nerve-growth signal, and improved functional recovery scores (Gusev et al., 2018).
- Although built on a fragment of ACTH, Semax acts without hormonal and toxic side effects, according to a 2021 paper summarising its stroke research (Filippenkov et al., Int J Mol Sci, 2021).
View product →What is Semax?
Semax is a synthetic seven-amino-acid peptide developed by Russian researchers. It joins the 4-7 fragment of adrenocorticotropic hormone (ACTH), the pituitary hormone that drives cortisol release, to a Pro-Gly-Pro tail, the same three amino acids added to Selank to improve its metabolic stability (Volkova et al., Front Pharmacol, 2016). That is why it is written as ACTH(4-7)PGP or described as an ACTH(4-10) analogue. Its developers described it as one of the rare regulatory peptide analogues to pass all stages from basic research to practical medical use (Ashmarin et al., 1997). Its research background is set out in What Is Semax? and Semax Benefits: What the Research Shows.
What do the human studies report?
The human studies were run mainly at Russian neurology centres and range from 27 to 187 patients. They report tolerability alongside the main outcomes.
Cerebrovascular insufficiency, 2005
A study of 187 patients with different stages of chronic cerebrovascular insufficiency, a reduced blood supply to the brain, evaluated both tolerability and clinical efficacy. Semax produced significant clinical improvement, stabilised the course of the disease and reduced the risk of stroke and transient ischemic attacks. The authors reported that it had a minor percentage of side effects and was well tolerated, including by older patients (Gusev, Skvortsova and Chukanova, Zh Nevrol Psikhiatr Im S S Korsakova, 2005).
Acute stroke, 1997
In 30 patients in the acute period of hemispheric ischemic stroke, compared with 80 similar patients on conventional therapy, adding Semax to intensive care increased the recovery of general and focal neurological deficits, especially motor function (Gusev et al., Zh Nevrol Psikhiatr Im S S Korsakova, 1997).
Stroke rehabilitation, 2018
A 2018 study followed 110 patients through early or late rehabilitation after ischemic stroke, with and without Semax. Semax raised plasma brain-derived neurotrophic factor (BDNF), a protein that supports nerve-cell survival and plasticity, and levels stayed high throughout the study. Semax and higher BDNF were linked to faster and better recovery on the Barthel index, a measure of independence in daily activities (Gusev et al., Zh Nevrol Psikhiatr Im S S Korsakova, 2018). More detail is in Semax and Stroke Recovery.
Motor neuron disease, 2007
In an open-label study of 27 patients with motor neuron disease, intranasal Semax significantly improved total quality-of-life scores, driven by better emotional state and motivation, with the largest effect on day 10 (Serdiuk et al., Zh Nevrol Psikhiatr Im S S Korsakova, 2007).
Attention and memory
The developers’ 1997 review reported that Semax improved memory and attention in healthy men working under extreme conditions, with effects lasting 20 to 24 hours after intranasal administration, and that in the majority of clinical uses it showed positive effects with no negative side actions or complications (Ashmarin et al., 1997).
Why does Semax not act like ACTH?
Semax keeps only the 4-7 fragment of ACTH, a hormone whose main role is to stimulate cortisol release from the adrenal glands. Summarising earlier stroke research, a 2021 paper described Semax as increasing the rate and extent of neurological recovery without hormonal and toxic side effects, while sharing several neuroprotective properties of the melanocortin peptides, such as protecting neurons from glutamate toxicity (Filippenkov et al., Int J Mol Sci, 2021).
How does Semax compare with Selank?
Semax and Selank come from the same Russian research group and share the Pro-Gly-Pro stabilising tail, but they start from different natural peptides and are studied for different questions: Semax for cognition and neuroprotection, Selank for anxiety. The comparison is in Semax vs Selank: What Actually Separates Them, and the safety record of Selank is in Selank Side Effects. For differences between nasal and injected research routes, see Semax and Selank: Intranasal vs Subcutaneous Research Routes.
Why research-grade quality and storage matter
Every Vistara Labs product is third-party tested, with certificates on the lab reports page. Semax is supplied as a lyophilised (freeze-dried) vial, as a ready-mixed metered nasal spray, and combined with Selank in the Selank + Semax Nasal Spray. Storage before and after mixing is covered in How Long Does Semax Last? and Semax Stability. Orders ship from within Canada by Canada Post Xpresspost.
Semax is supplied for laboratory research use only. The human studies above were clinical research carried out under medical supervision.
Frequently asked questions
What side effects have Semax studies reported?
In a study of 187 patients with cerebrovascular insufficiency, Semax was well tolerated with a minor percentage of side effects, including in older patients. Its developers reported that in clinical use it produced no negative side actions or complications connected with its administration.
What did Semax research show in stroke patients?
In 30 patients with acute ischemic stroke, adding Semax increased recovery of neurological deficits, especially motor function. In 110 patients in rehabilitation, Semax raised plasma BDNF and was linked to faster and better recovery of daily function.
Does Semax have hormonal effects like ACTH?
Semax keeps only a short fragment of ACTH, joined to a stabilising Pro-Gly-Pro tail. A 2021 paper summarising its stroke research described it as improving neurological recovery without hormonal and toxic side effects.
How is Semax given in the human studies?
Most of the published clinical work used intranasal Semax, the route its developers studied. Their review reported effects on memory and attention lasting 20 to 24 hours after intranasal administration.
Where can I buy Semax in Canada?
Vistara Labs supplies Semax as a lyophilised vial, a ready-mixed nasal spray and a combined Selank + Semax spray, third-party tested and shipped from within Canada by Canada Post Xpresspost.
Product details from vistaralabs.ca, October 2026. Sources: Gusev EI, Skvortsova VI, Chukanova EI. Semax in prevention of disease progress and development of exacerbations in patients with cerebrovascular insufficiency. Zh Nevrol Psikhiatr Im S S Korsakova. 2005. PMID 15792140. Ashmarin IP et al. A nootropic adrenocorticotropin analog 4-10, Semax (15 years experience in its design and study). Zh Vyssh Nerv Deiat Im I P Pavlova. 1997. PMID 9173745. Gusev EI et al. Effectiveness of Semax in acute period of hemispheric ischemic stroke. Zh Nevrol Psikhiatr Im S S Korsakova. 1997. PMID 11517472. Gusev EI et al. The efficacy of Semax in the treatment of patients at different stages of ischemic stroke. Zh Nevrol Psikhiatr Im S S Korsakova. 2018. PMID 29798983. Serdiuk AV et al. The study of chronic partial denervation and quality of life in patients with motor neuron disease treated with Semax. Zh Nevrol Psikhiatr Im S S Korsakova. 2007. PMID 18379501. Filippenkov IB et al. Brain protein expression profile confirms the protective effect of the ACTH(4-7)PGP peptide (Semax) in a rat model of cerebral ischemia-reperfusion. Int J Mol Sci. 2021. PMID 34201112. Volkova A et al. Selank administration affects the expression of some genes involved in GABAergic neurotransmission. Front Pharmacol. 2016. PMID 26924987.
More on this: Buy Semax in Canada: A Researcher’s Guide.
All products supplied by Vistara Labs are intended for laboratory research use only. They are not drugs, are not approved for human or veterinary use, and are not intended to diagnose, treat, cure or prevent any condition. Nothing on this page constitutes medical advice or guidance for use in humans.
References
Semax has human research, mostly small studies concentrated in Russian-language literature rather than large modern placebo-controlled trials.
- [The efficacy of semax in the tretament of patients at different stages of ischemic stroke]Clinical study of 110 people after ischaemic stroke, with and without Semax; not a large modern placebo-controlled randomised trial.
- Effects of Semax on the Default Mode Network of the BrainSmall human study; 24 healthy volunteers, intranasal Semax versus placebo, resting-state fMRI. Mechanistic — does not establish improved cognition.
- [Effectiveness of semax in acute period of hemispheric ischemic stroke (a clinical and electrophysiological study)]Clinical study; 30 acute ischaemic stroke patients against an 80-patient conventional-treatment control cohort.
Links open the study record on PubMed so the source can be checked directly. Listing a study is not a claim that its findings apply to any other use, product or route of administration. Research use only.
