Drug interactions
Iodine + Methimazole
Severity: Moderate
Iodine and Methimazole: moderate interaction.
Last updated
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Systemic iodine affects thyroid hormone production and release, so combining it with an antithyroid drug may lead to unpredictable thyroid control. Excess iodine can add to hypothyroid or goitrogenic effects.
What this interaction means in plain words
Iodine and Methimazole can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Iodine belongs to Dermatology; Methimazole belongs to Endocrine.
Why it happens
Excess iodide inhibits thyroid hormone release and synthesis, adding to thyroid peroxidase inhibition.
What to do
Monitor thyroid function and avoid unnecessary iodine supplements during methimazole therapy unless used deliberately, for example before thyroid surgery.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Methimazole
- Carbamazepine + Methimazole Major
- Clozapine + Methimazole Major
- Methimazole + Propylthiouracil Major
- Methimazole + Sodium iodide i-131 Major
- Iodinated glycerol + Methimazole Moderate
- Lycopus + Methimazole Moderate
Other interactions of Iodine
- Iodine + Lithium Moderate
- Iodine + Propylthiouracil Moderate
Frequently asked questions
Can I take Iodine with Methimazole?
MediHelp rates the interaction as moderate. Iodine and Methimazole can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Systemic iodine affects thyroid hormone production and release, so combining it with an antithyroid drug may lead to unpredictable thyroid control. Excess iodine can add to hypothyroid or goitrogenic effects.
How serious is the interaction between Iodine and Methimazole?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor thyroid function and avoid unnecessary iodine supplements during methimazole therapy unless used deliberately, for example before thyroid surgery.
What other medicines interact with Methimazole?
MediHelp also lists interactions of Methimazole with, for example, Carbamazepine, Clozapine, Propylthiouracil. The full list is on the Methimazole page.
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