Lanthanum and Methimazole interaction
Lanthanum and Methimazole: the Lanthanum prescribing label flags this combination with the strongest language, such as a contraindication, a boxed warning, or an instruction to avoid it.
Do not combine without a prescriber's guidance. The label language below is the strongest FDA uses.
What the FDA labels say
From the Lanthanum (Lanthanum carbonate) label · effective 2025-12-15
Do not take thyroid hormone replacement therapy within 2 hours of dosing with LANTHANUM CARBONATE.
Examples of relevant classes of compounds where antacids have been demonstrated to reduce bioavailability include antibiotics (such as quinolones, ampicillin, and tetracyclines), thyroid hormones, ACE inhibitors, statin lipid regulators, and anti-malarials.
Levothyroxine The bioavailability of levothyroxine was decreased by approximately 40% when taken together with LANTHANUM CARBONATE.
Administer thyroid hormone replacement therapy at least 2 hours before or 2 hours after dosing with LANTHANUM CARBONATE and monitor thyroid stimulating hormone (TSH) levels [see Clinical Pharmacology (12.3) ] .
Taking more than these two? Interactions stack. Check your whole list at once; it stays in your browser.
Open in the checkerNot medical advice. Interaction Checker quotes FDA label text and NIH fact sheets. Whether an interaction matters for you depends on doses, timing, kidney and liver function, and other conditions. Confirm with a pharmacist or prescriber.