What should you know about radioactive iodine and hyperthyroidism?

Hyperthyroidism means the thyroid is making more hormone than the body needs. Radioactive iodine is swallowed, absorbed mainly by thyroid cells, and gradually damages the overactive tissue. The treatment does not work instantly, so symptoms and thyroid blood tests are monitored while hormone levels change.

People with hyperthyroidism may experience palpitations, excessive sweating, heat intolerance, diarrhoea, difficulty sleeping, or feeling anxious. These symptoms are not specific to one condition, and treatment choice depends on the cause, thyroid size, eye symptoms, pregnancy plans, and other health factors.

Your specialist will explain whether to pause medicines, how to take the dose, and what temporary contact precautions apply. Follow instructions about distance from others, hygiene, and handling laundry or bodily fluids. Pregnancy and breastfeeding must be discussed before treatment, and pregnancy should be avoided for the period your specialist advises.

Keep scheduled thyroid blood tests. You may need symptom-control medicine while the radioactive iodine takes effect. Do not change thyroid medicines on your own, even if you feel better or notice symptoms changing.

Seek urgent help for chest pain, severe breathlessness, fainting, a very fast or irregular heartbeat, confusion, or sudden vision changes. Contact your treatment team promptly if vomiting prevents you from keeping medicines down or if symptoms become markedly worse.

Ask why radioactive iodine is suitable for your cause of hyperthyroidism, how it affects thyroid eye disease, which medicines to stop, what precautions apply at home, and how follow-up will detect a low thyroid state.