Methimazole and Tirzepatide interaction
Methimazole and Tirzepatide: the Tirzepatide prescribing label flag 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 Tirzepatide (Zepbound) label · effective 2026-08-28
WARNING: RISK OF THYROID C-CELL TUMORS In rats, tirzepatide causes dose-dependent and treatment-duration-dependent thyroid C-cell tumors at clinically relevant exposures.
It is unknown whether ZEPBOUND causes thyroid C-cell tumors, including medullary thyroid carcinoma (MTC), in humans as human relevance of tirzepatide-induced rodent thyroid C-cell tumors has not been determined [see Warnings and Precautions ( 5.1 ) and Nonclinical Toxicology ( 13.1 )].
Counsel patients regarding the potential risk for MTC with the use of ZEPBOUND and inform them of symptoms of thyroid tumors (e.g., a mass in the neck, dysphagia, dyspnea, persistent hoarseness).
Routine monitoring of serum calcitonin or using thyroid ultrasound is of uncertain value for early detection of MTC in patients treated with ZEPBOUND [see Contraindications ( 4 ) and Warnings and Precautions ( 5.1 )].
WARNING: RISK OF THYROID C-CELL TUMORS See full prescribing information for complete boxed warning.
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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.