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Limited human dataNot FDA approved

Semax side effects

Also known as: MEHFPGP · Met-Glu-His-Phe-Pro-Gly-Pro · ACTH(4-10) analog · ACTH(4-7)PGP · (Pro8,Gly9,Pro10)ACTH-(4-10) · Semax acetate

Updated 73 sources

11 side effects reported for Semax: 5 from studies and labels, 6 from users and guides. 3 come with the ways people manage them.

Semax overview

Side effects reported in studies and labels

Rates as each trial or label states them. A rate from one trial does not carry over to research-grade vials or other doses.

From trials and regulators5

Clinical studies and regulatory documents.

  • Mild nasal irritation

    Listed on the Russian label with prolonged use; no rate given

  • Nasal cavity discoloration

    About 10% of patients, per a research summary citing a 2013 study

  • Raised blood glucose in people with diabetes

    7.4% figure in a research summary citing a 2013 study

  • Eye pain and burning

    One FDA adverse event report, with hospitalization, after 0.1% drops bought online; no case reports in the literature

  • Possible bleeding risk

    Theoretical. FDA reviewers flag a possible anti-clotting effect; no cases reported

Side effects users and guides report

What people post and what dosing guides list. These are reports, not measured rates.

From users and guides6

Community reports, competitor and vendor guides, media.

  • Anxiety, overstimulation or racing heart

    Commonly reported on r/Peptides; one user describes about an hour of overstimulation unless Semax is taken with Selank

    How people manage it

    • Pair it with Selank, the most common fix users describe
    • Take it before noon and start low
    • Cycle off or switch route

  • Irritability

    Several r/Peptides users report sharper focus together with irritability

  • Headache

    Occasional r/Peptides reports, including a low but persistent headache

    How people manage it

    • One user tolerated Selank better than Semax for headaches

  • Hair shedding

    Anecdotal claims and questions on r/Peptides. One guide calls it anecdotal, another rare in predisposed people. Neither the label nor any study reports it.

  • Next-day fatigue or low HRV

    A few r/Peptides reports, including feeling more tired at the end of the day

  • Fading effect

    One r/Peptides user says the effect drops sharply after the first or second vial

    How people manage it

    • Cycle off

Who should avoid it, and what not to combine

  • Anxiety disordersCondition

    Listed as a contraindication on the Russian label.

  • Acute psychosisCondition

    Listed as a contraindication on the Russian label.

  • History of seizuresCondition

    Listed as a contraindication on the Russian label.

  • PregnancyCondition

    Listed as a contraindication on the Russian label.

  • Children under 7Condition

    The Russian label does not allow use under age 7.

  • Stimulants and racetamsSubstance

    One guide advises caution when combining them with Semax.

How much is known

Limited human data

In Russian clinical use since the 1990s. Human data are mostly Russian-language stroke studies (30 treated vs 80 controls; 110 patients) and two small healthy-volunteer brain imaging studies. Animal data on BDNF and on dopamine and serotonin are strong. A research summary says well-conducted published trials are lacking, FDA found no human pharmacokinetic studies, and one guide counts no ClinicalTrials.gov entries.

Sources for these side effects

19 sources, each checked by date. Record updated Oct 24, 2026. Numbers are restated in our own words and labelled by where they came from.

Clinical study1

  1. Cognitive Vitality for Researchers: SemaxAlzheimer's Drug Discovery Foundation, via a reference work · checked Oct 23, 2026

Regulatory3

  1. Semax 0.1% nasal drops (Russian label)Vidal, via a reference work · checked Oct 24, 2026
  2. Semax instruction for use (English translation of the Russian label)Peptogen (label translation), via a vendor guide · checked Oct 23, 2026
  3. FDA briefing document: Semax-related bulk drug substances, PCAC July 23-24 2026FDA · checked Oct 23, 2026

Competitor guide3

  1. Semaxpeptidesexplorer.com · checked Oct 23, 2026
  2. Semaxpeptidedeck.com · checked Oct 23, 2026
  3. Semaxpeptiq.io · checked Oct 23, 2026

Community-reported12

  1. Interested in SEMAX and SELANK blendsr/Peptides · checked Oct 23, 2026
  2. r/Peptides comment on Semaxr/Peptides · checked Oct 23, 2026
  3. r/Peptides comment on Semaxr/Peptides · checked Oct 23, 2026
  4. r/Peptides comment on Semaxr/Peptides · checked Oct 23, 2026

Back to the full Semax page for dosing, the vial chart and storage.