Thymalin is unusual among the compounds on this site: it has a label. Not an American one, but a Russian prescription registration with a stated dose, a course length, children's doses and contraindications. It is also not a single peptide. The registered product is an extract of calf thymus glands, dosed by milligrams of extract, which matters for anyone reading a research vial labelled "thymalin 10 mg" as though it were one molecule. This page sets out the label, the one randomised trial, the wider literature and the units per vial.
Related immune compounds are on the thymosin alpha-1 dosage page, the KPV dosage page and the page on the cathelicidin LL-37 and its trial concentrations; the 2003 report below pairs thymalin with epithalamin, a pineal extract, and the synthetic peptide epitalon is on the epithalon dosage page. All compounds with label figures are compared on the peptide dosage chart.
The registered product
| Item | What the Russian entry states |
|---|---|
| Name and form | Thymalin, lyophilisate for solution for intramuscular injection |
| Strength | 10 mg per vial; packs of 5 or 10 vials |
| Active substance | Thymus extract from calves and young cattle under one year old, 10 mg |
| Excipient | Glycine 20 mg |
| Holder and registration | Samson-Med, LP-№(005867)-(RG-RU), 2024-06-21, no expiry |
| Class | Immunostimulant (ATC L03AX) |
| Status | Prescription only |
The entry lists immunodeficiency in adults and children from six months as the indication, in infections, after radiation or thymus surgery, with impaired tissue repair and similar conditions. It names allergic reactions as the possible side effect, and pregnancy and breastfeeding as contraindications.
The dose table, as registered
| Group | Daily dose (intramuscular) | Duration | Course |
|---|---|---|---|
| Adults, treatment | 5–20 mg | 3–10 days | 30–100 mg |
| Adults, prevention | 5–10 mg | 3–5 days | — |
| Children 6–12 months | 1 mg | 3–10 days | — |
| Children 1–3 years | 1.5–2 mg | 3–10 days | — |
| Children 4–6 years | 2–3 mg | 3–10 days | — |
| Children 7–14 years | 3–5 mg | 3–10 days | — |
| Children, prevention | 1–5 mg | 3–5 days | — |
A repeat course is allowed after one to six months. The entry gives no diluent volume and no dose adjustment for kidney or liver impairment or for older patients, stating that data are absent.
What the trials used
The only randomised study found with a stated dose is a 2021 paper from the developer's group on COVID-19: 92 hospitalised patients, 42 given thymalin 10 mg intramuscularly once a day for five days on top of standard treatment and 50 given standard treatment alone, randomised by sealed envelope. The authors report faster falls in IL-6, C-reactive protein and D-dimer in the thymalin group. It is small, it reports laboratory markers rather than clinical outcomes as its main results, and it was run by the drug's developers.
The rest of the 293 PubMed records span five decades and are mostly Russian- and Ukrainian-language papers on immune markers in burns, tuberculosis, pancreatitis, otitis and other conditions, alongside animal and cell work. The longevity claim usually attached to thymalin comes from a 2003 report by the St Petersburg institute that developed it: older people given thymalin, epithalamin or both in the first two to three years of a six-to-eight-year observation had lower mortality than controls. The abstract describes no randomisation and no doses, and reports a 4.1-fold mortality reduction in a group treated annually for six years.
Reconstitution and the units per draw
Units on a U-100 syringe = mg ÷ mg/mL × 100. Research vials are sold at 5, 10 and 20 mg.
| Amount | 10 mg/mL | 5 mg/mL | 2.5 mg/mL |
|---|---|---|---|
| 1 mg | 10 units | 20 units | 40 units |
| 5 mg | 50 units | 100 units | 200 units |
| 10 mg | 100 units | 200 units | 400 units |
| 20 mg | 200 units | 400 units | 800 units |
10 mg/mL is a 10 mg vial with 1 mL or a 20 mg vial with 2 mL; 5 mg/mL is a 10 mg vial with 2 mL. The registered adult doses fill or overflow a 1 mL insulin syringe at every concentration in the table, because thymalin is dosed in milligrams of extract, not micrograms, and because the label's route is intramuscular. A U-100 insulin syringe is made for subcutaneous injection; the arithmetic shows volume only. The thymalin calculator setting works other vials and volumes.
What is not established
Thymalin has no label outside Russia, no registered trial, and one small randomised study with a stated dose, run by its developers. A research vial labelled "thymalin" states no animal source, no extract standard and no dipeptide content, so whether its 10 mg matches the registered product's 10 mg cannot be read from the label. The longevity figures are observational. Nothing on this page is a dose or a course to follow; the compound is covered in Medibact's Thymalin guide, and dosing decisions belong with a prescriber.
Sources and dates
Opened 2026-10-10: the Vidal Russia entry for Thymalin lyophilisate 10 mg (Samson-Med, updated 2025-03-25: composition, indications, dosage, contraindications); the PubMed search for thymalin (293 records) and the abstracts of Khavinson and Morozov 2003 (PMID 14523363) and Linkova et al. 2023 (PMID 37686182); the full text of Khavinson et al. 2021 (PMC7877506, PMID 33575961); openFDA and ClinicalTrials.gov searches for thymalin (none); FDA's page on bulk drug substances that may present significant safety risks (content current as of 2026-04-22; thymalin not listed). Units are arithmetic by this site. Corrections go to the contact page.