Hyperthyroidism, or overactive thyroid, happens when your thyroid gland makes more thyroid hormones than your body needs.
Hyperthyroidism has several causes. They include the following:
n Graves’ disease, an autoimmune disorder in which your immune system attacks your thyroid.
n Thyroid nodules, which are growths on your thyroid.
n Thyroiditis, inflammation of the thyroid.
n Too much iodine. Iodine is found in some medicines, cough syrup, seaweed, and seaweed-based supplements.
The symptoms of hyperthyroidism can vary from person to person and may include the following:
n Nervousness or irritability.
n Fatigue and trouble sleeping.
n Muscle weakness and weight loss.
n Trouble tolerating heat.
n Tremor, usually in your hands.
n Rapid and irregular heartbeat.
n Mood swings.
n Goiter, an enlarged thyroid that may cause your neck to look swollen.
If you have symptoms of hyperthyroidism, it’s important to talk to your health care provider about which foods, supplements, and medicines you need to avoid.
For more information about hyperthyroidism go to: medlineplus.gov/hyperthyroidism.html.
— Benefits and Wellness,
Human Resources, 9-18-25
