Does Methimazole Interact with Adrenergic Blockers?
Methimazole and Adrenergic Blockers have a moderate drug interaction according to U.S. FDA drug labeling data. Hyperthyroidism increases clearance of beta blockers; dose reduction may be needed when hyperthyroid patient becomes euthyroid with methimazole treatment. The mechanism involves increased clearance of beta blockers with high extraction ratio in hyperthyroid state. Patients taking both medications should consult their healthcare provider before starting, stopping, or changing the dosage of either drug. This information is based on official FDA drug labeling sourced from OpenFDA and the NIH National Library of Medicine.
- Severity
- Moderate
- Methimazole Class
- Thyroid Hormone Synthesis Inhibitor
- Management
- Monitor for effects
- Data Source
- U.S. FDA via OpenFDA
How This Interaction Works
The interaction between Methimazole and Adrenergic Blockers occurs because increased clearance of beta blockers with high extraction ratio in hyperthyroid state. Clinically, this means hyperthyroidism increases clearance of beta blockers; dose reduction may be needed when hyperthyroid patient becomes euthyroid with methimazole treatment. This is classified as a moderate interaction. While it may not require stopping either medication, your healthcare provider should be aware you are taking both so they can monitor for potential effects and adjust treatment if necessary.
What To Tell Your Doctor or Pharmacist
If you are taking Methimazole and your doctor is considering prescribing Adrenergic Blockers (or vice versa), make sure to:
- Inform your doctor and pharmacist of all current medications, including over-the-counter drugs and supplements
- Ask whether the benefits of combining these medications outweigh the risks for your specific situation
- Ask what symptoms to watch for that would indicate the interaction is causing problems
- Ask whether any dosage adjustments are needed
- Never stop or change either medication without first consulting your healthcare provider