Is Selenium Safe with Armour Thyroid?
Free · No account · based on published sources including NIH ODS, FDA drug labels, and peer-reviewed literature
Selenium supplementation at physiologic doses (55–200 mcg/day) may be beneficial in autoimmune thyroid disease (Hashimoto's) but should not exceed 400 mcg/day due to toxicity risk. Discuss selenium supplementation with your physician before starting. It is not a replacement for medication.
Why this interaction occurs
Selenium is an essential cofactor for iodothyronine deiodinase enzymes (types 1, 2, and 3), which convert inactive T4 to active T3. In patients on Armour Thyroid (which contains both T4 and T3), selenium status influences peripheral thyroid hormone conversion. Clinical studies in Hashimoto's thyroiditis show selenium supplementation reduces thyroid peroxidase antibodies and may improve thyroid function, but excess selenium is toxic.
Evidence
Evidence level: moderate.
Reported safety data
The FDA’s adverse event reporting system (FAERS) has received 159,660 reports mentioning Armour Thyroid. This reflects reported cases involving the medication in general — not confirmed causation, and not specific to the Armour Thyroid + 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 Selenium interactions → · All Armour Thyroid interactions →
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Educational only — not medical advice.
Always confirm with your doctor or pharmacist.