Is Calcium Safe with Liothyronine?
Free · No account · based on published sources including NIH ODS, FDA drug labels, and peer-reviewed literature
Take calcium supplements at least 4 hours apart from Liothyronine. Take your thyroid medication on an empty stomach first thing in the morning, then wait before taking calcium.
Why this interaction occurs
Calcium carbonate and calcium citrate form insoluble complexes with thyroid hormones in the gastrointestinal tract, significantly reducing the absorption of T3 by up to 20-40%. This can lead to hypothyroid symptoms and require dose adjustments.
Evidence
Evidence level: strong.
Reported safety data
The FDA’s adverse event reporting system (FAERS) has received 8,329 reports mentioning Liothyronine. This reflects reported cases involving the medication in general — not confirmed causation, and not specific to the Liothyronine + 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 Calcium interactions → · All Liothyronine interactions →
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Educational only — not medical advice.
Always confirm with your doctor or pharmacist.