Iodine and hyperthyroidism: what to know

The thyroid uses iodine to make hormones that influence metabolism. A person with an overactive thyroid, thyroid nodules, or another thyroid disorder may respond differently to a sudden increase in iodine than someone with a normally regulated gland. Symptoms of hyperthyroidism can include palpitations, excessive sweating, heat intolerance, feeling anxious, difficulty sleeping, diarrhoea, or night sweats. Hyperthyroidism presents with these symptoms; the symptoms themselves do not establish the diagnosis.

Tell your clinician about iodine-containing supplements, seaweed products, medicines, antiseptics, and recent imaging. Do not start or stop a supplement or thyroid medicine without advice. A clinician may check symptoms, examine the neck and pulse, and arrange thyroid blood tests. Keep a note of when symptoms began and whether they followed a new product. Learn more about [Hyperthyroidism](/conditions/hyperthyroidism/) if you have been given that diagnosis.

Arrange medical review for new or worsening palpitations, persistent sweating, unexplained diarrhoea, marked anxiety, or poor sleep. Seek urgent help for chest pain, severe breathlessness, fainting, confusion, or a very fast or irregular heartbeat. People already treated for thyroid disease should contact their care team promptly when symptoms change, because treatment may need adjustment.

Ask whether your iodine intake is relevant, which products to avoid or continue, and whether thyroid tests are needed. Ask how to recognise a concerning change and when your next review should occur.