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Overactive thyroid (hyperthyroidism): the signs, getting a diagnosis, the treatments, and Graves’ disease
For anyone whose heart races, whose hands shake, or who is losing weight without trying and wondering about their thyroid; anyone just told they have hyperthyroidism or Graves’ disease; anyone choosing between medicine, radioactive iodine and surgery, or taking antithyroid medicine; anyone pregnant with a thyroid problem; and anyone caring for someone with one. The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK, part of the NIH) says hyperthyroidism is when the thyroid gland makes more thyroid hormones than the body needs; that about 1 out of 100 Americans ages 12 and older have it; and that Graves’ disease causes about 4 out of 5 cases. This page passes on, by name, what NIDDK says: the signs and what it can do untreated, who gets it and the causes, the tests, the treatments and the side effects to call about, and Graves’ eye disease, iodine and pregnancy. It builds the words to say to a doctor, and prints a card to keep.
A word with a dotted line under it, like this, opens its official definition, quoted from a U.S. government glossary.
Right now
- Chest pain, fainting, trouble breathing, or signs of a stroke (a face that droops, an arm that is weak, speech that is slurred): call 911 (ours). NIDDK says untreated hyperthyroidism can cause an irregular heartbeat that can lead to blood clots, stroke and heart failure.
- Taking antithyroid medicine and have a fever, chills or a constant sore throat, yellow skin or eyes, dull belly pain, loss of appetite, a rash, itching or easy bruising, or fatigue or weakness? NIDDK says to call your doctor right away.
- A heartbeat that is very fast or irregular and does not settle? Call your doctor the same day, and if you cannot reach them, go to urgent care (ours).
- Thoughts of suicide? Call or text 988, any hour (ours).
More help
- Linked to it, on this site: Underactive thyroid (hypothyroidism) · Atrial fibrillation · Stroke · Osteoporosis · Diabetes · Anxiety · Eye care.
- The medicine, smoking and pregnancy: My medicines list · When medicine costs too much · Quitting smoking · Pregnancy and a new baby.
- Care and costs: When you need a doctor and can’t pay · Symptom diary · Get ready for your appointment.
- In a crisis: Help right now (988, 911). All our free tools.
This page and its wording were written with AI (Claude) for Scarlet Beast (our AI policy). No doctor or nurse has reviewed it. The facts were read on October 16, 2026 on two NIDDK pages (NIH): Hyperthyroidism (Overactive Thyroid) (last reviewed August 2021) and Graves’ Disease (last reviewed November 2021). Ours: calling 911 for chest pain, fainting, trouble breathing, or signs of a stroke, and the signs of a stroke we list; calling the doctor the same day for a heartbeat that is very fast or irregular and does not settle; telling the doctor about eye pain or a change in vision; saying so before a radioactive iodine test if pregnant or breastfeeding, and calling that week on finding out about a pregnancy; 988 for thoughts of suicide; not stopping or changing a medicine on your own; the questions to ask at a visit; health centers and medicine costs when money is tight; and the order of the steps. What we left out: brand names, doses, the names of single beta-blockers, test number ranges, radiofrequency ablation (NIDDK says it is new and not yet widely available), research studies, and clinical pages for providers. This page saves nothing and loads no trackers.