Limited human dataNot FDA approved

Thymalin side effects

Also known as: Timalin · Тималин · Thymus extract · Thymus polypeptides

Updated Oct 24, 202619 sources

4 side effects reported for Thymalin: 1 from studies and labels, 3 from users and guides.

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 regulators1

Clinical studies and regulatory documents.

Allergic reaction
Possible; the only adverse effect the Russian label lists

Side effects users and guides report

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

From users and guides3

Community reports, competitor and vendor guides, media.

Injection-site reactions
Reported
Allergy in people sensitive to beef protein
Possible, since it is a bovine extract
Generally well tolerated
Consistently described as well tolerated in community reports

Who should avoid it, and what not to combine

Pregnancy and breastfeedingCondition
Contraindicated on the Russian label.
Known intolerance to thymalin or glycineCondition
Contraindicated on the label; use with caution after past severe allergies.
Autoimmune diseaseCondition
Raising T-cell activity could worsen it, so guides say avoid.
Immunosuppression after an organ transplantCondition
It works against the drugs that keep the transplant safe; guides urge caution.

How much is known

Limited human data

Almost all human data come from one Russian research network. A cohort of 266 elderly people followed 6 to 8 years reported 2.0 to 2.1-fold lower mortality on thymalin and 2.5-fold on thymalin plus epithalamin; the abstract does not describe randomization. Small Russian studies used it in severe COVID-19. No Western randomized trial exists and ClinicalTrials.gov lists none.