Is Methimazole / Propylthiouracil (antithyroid drugs) Safe with Selenium?
Free · No account · based on published sources including NIH ODS, FDA drug labels, and peer-reviewed literature
Use selenium supplements cautiously if prescribed antithyroid medications for hyperthyroidism. Discuss supplementation with your endocrinologist, as selenium's anti-inflammatory effects on thyroid tissue may alter the required dose of antithyroid medication.
Why this interaction occurs
Selenium has demonstrated immunomodulatory effects in Graves' disease, reducing thyroid antibody titers (TPO-Ab, TSH-R-Ab) and thyroid inflammatory activity. Clinical trials (GRASS trial) show selenium may reduce disease activity in Graves' hyperthyroidism, potentially necessitating downward dose adjustments of methimazole or PTU to avoid iatrogenic hypothyroidism.
Evidence
Evidence level: moderate.
Reported safety data
The FDA’s adverse event reporting system (FAERS) has received 5,677 reports mentioning Selenium. This reflects reported cases involving the medication in general — not confirmed causation, and not specific to the Selenium + supplement combination on this page.
FAERS reports are voluntary and cannot prove that a drug caused an event. Do not use report counts to assess the safety of this specific drug-supplement pair.
Frequently asked questions
Related interactions
All Methimazole / Propylthiouracil (antithyroid drugs) interactions → · All Selenium interactions →
Already checked this one — check your whole list
Educational only — not medical advice.
Always confirm with your doctor or pharmacist.