Amiodarone-Induced Thyroid Disease
Amiodarone is a highly effective medication for heart rhythm problems, but it contains large amounts of iodine and can disturb thyroid function in two opposite directions — causing either an overactive or an underactive thyroid.
Because the drug is often essential, the thyroid problem is managed alongside it rather than by simply stopping it.
Last medically reviewed: 15 November 2025
Why it affects the thyroid
Amiodarone is rich in iodine, which the thyroid uses to make hormone, and it also directly affects thyroid hormone metabolism. This can lead to excess hormone production (amiodarone-induced thyrotoxicosis) or to an underactive thyroid (amiodarone-induced hypothyroidism).
The thyroid effects can begin months or even years after starting the drug.
Detection
Thyroid function should be checked before starting amiodarone and periodically thereafter. Symptoms such as palpitations, weight change, tremor, fatigue or cold intolerance should prompt testing.
Distinguishing the type of thyroid problem may require additional tests, and sometimes imaging, because the usual picture can be atypical.
Management
An underactive thyroid is treated with levothyroxine while amiodarone continues. An overactive thyroid is more complex and may need antithyroid drugs, steroids or, occasionally, surgery — decided with a specialist, sometimes in discussion with the cardiology team.
Stopping amiodarone is not always possible or wise, so management focuses on controlling the thyroid problem safely.
Frequently asked questions
Should I stop amiodarone if my thyroid is affected?
No — never stop a heart rhythm medication without specialist advice. The thyroid problem is usually managed while the drug continues.
How often should thyroid be checked on amiodarone?
Thyroid function is typically checked before starting and then periodically, with testing sooner if symptoms develop.
Is the thyroid effect permanent?
Not always — an underactive thyroid caused by amiodarone may recover after the drug is stopped, but it often needs treatment while the drug continues.
References & further reading
This page is based on established medical knowledge and guidelines from authoritative sources. Always consult a qualified clinician for personal medical advice.
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