Levothyroxine and Propranolol interaction
Levothyroxine and Propranolol: both prescribing labels 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 Propranolol (InnoPran XL) label · effective 2026-08-27
Avoid abrupt withdrawal of beta-blockade, which may precipitate a thyroid storm.
From the Levothyroxine (Levothyroxine Sodium) label · effective 2024-07-10
Drug or Drug Class Effect Beta-adrenergic antagonists e.g., Propranolol > 160 mg/day) In patients treated with large doses of propranolol (> 160 mg/day), T 3 and T 4 levels change slightly, TSH levels remain normal, and patients are clinically euthyroid.
It should be noted that actions of particular beta-adrenergic antagonists may be impaired when the hypothyroid patient is converted to the euthyroid state.
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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.