Semax

Semax is a lab-made peptide of seven amino acids (methionine, glutamic acid, histidine, phenylalanine, proline, glycine, proline), an analog of ACTH (4-10), a fragment of the hormone ACTH. In Russia it is a registered nootropic drug sold as 0.1% and 1% nasal drops. It has no monograph in the European, Japanese or International Pharmacopoeia, and it is not FDA-approved.

Not yet, and maybe not at all. On July 24, 2026 the FDA’s Pharmacy Compounding Advisory Committee reviewed semax for cerebral ischemia, migraine and trigeminal neuralgia. FDA staff had concluded that “a balancing of the criteria weighs against” adding it, but the committee voted to recommend adding semax to the 503A bulks list, one of six peptides it recommended in a narrow overall vote. The vote is not binding: the FDA would have to publish a proposed rule and take comments, a process that can last up to a year. As of October 16, 2026 no proposed or final rule had been published.

Nobody has measured them well. The FDA found no human safety data for injected semax and no human pharmacokinetic studies. Its search of the FDA Adverse Event Reporting System through December 3, 2025 found one report: a consumer had eye pain and burning after using semax 0.1% nasal drops bought online in May 2024, reported being hospitalized, and said a year later that the pain had not gone away. One report cannot show how common a side effect is, and a low number of reports is not evidence of safety.

They are the same peptide in two chemical forms: the free base, and an acetate salt. The FDA says “Semax acetate and semax (free base) are different active pharmaceutical ingredients and hence are considered different BDSs” (bulk drug substances), and it reviewed both. It also found that websites selling semax do not say which form their products contain. The FDA’s safety and effectiveness conclusions apply to both forms.

Its status is unclear. A 2025 review of “brain doping” substances places semax in a table of substances with “unclear” status, presumed to meet WADA criteria, and names tetracosactide (class S2) as the similar prohibited substance. If you are tested, ask your sport’s anti-doping body before using it.

There is no single correct amount. The water only sets the concentration: mg in the vial ÷ mL of water = mg per mL. For example (numbers for illustration only, not a dose), 10 mg of semax in 5 mL makes 2 mg/mL, so each unit on a U-100 insulin syringe holds 0.02 mg (20 mcg). The same vial in 10 mL makes 1 mg/mL, or 0.01 mg (10 mcg) per unit. More water means each unit holds less; less water means each unit holds more. The reconstitution calculator does this arithmetic for your vial. The FDA’s 2026 review cites reports that semax free base dissolves in water only “up to 2 mg/mL,” so a stronger mix than the first example may not dissolve fully; it found no water solubility data for semax acetate. The same review cites reports that lyophilized semax free base keeps for 4 years at -20°C, and that once mixed it should be kept at +4°C “for up to 2-7 days.” The only registered semax product is nasal drops, not an injectable vial. Because this product is not FDA-approved, no official label sets a water volume, and the contents of unapproved vials are not verified. Talk to a licensed prescriber or pharmacist before using any unapproved product. See also how long reconstituted peptides last.