Hyperthyroidism is treated with one of three main approaches: medication that slows thyroid hormone production, radioactive iodine that permanently reduces thyroid activity, or surgery to remove part or all of the thyroid gland. The right choice depends on what’s causing the overactive thyroid, how severe it is, your age, and whether you’re pregnant or planning to become pregnant. Most people also take a second medication for quick relief of symptoms like rapid heartbeat and tremors while the primary treatment takes effect.
Beta Blockers for Immediate Symptom Relief
Before addressing the thyroid itself, most doctors will prescribe a beta blocker to control the symptoms that make hyperthyroidism so uncomfortable: racing heart, shaking hands, anxiety, and heat intolerance. These drugs work fast, often within hours, and they do more than just mask symptoms. They also block the conversion of one thyroid hormone into its more active form, which directly helps bring hormone levels down.
Propranolol, taken every eight hours, is the most commonly used option. Metoprolol, taken once daily, works equally well for controlling the cardiovascular effects. Beta blockers are meant as short-term support while the primary treatment kicks in, not as a standalone solution.
Antithyroid Medications
Antithyroid drugs are the most conservative first-line treatment. They work by interfering with the thyroid’s ability to produce hormones, gradually bringing levels back to normal over weeks to months. The two main options are methimazole and propylthiouracil (PTU). Methimazole is generally preferred because it can be taken once daily and has fewer serious side effects. PTU requires dosing three times a day and carries a higher risk of liver toxicity.
A typical starting course involves taking medication daily for 12 to 18 months, then tapering off to see whether the thyroid stays under control on its own. For Graves’ disease, the most common cause of hyperthyroidism, about 20% to 30% of patients in the United States achieve lasting remission after completing this course. That means the majority will eventually relapse and need either a second round of medication or a more definitive treatment like radioactive iodine or surgery.
The most serious risk of antithyroid drugs is a condition called agranulocytosis, where your white blood cell count drops dangerously low and leaves you vulnerable to infections. This is rare, occurring in roughly 0.2% to 0.5% of patients taking these medications. Symptoms to watch for include sudden high fever, severe sore throat, or mouth ulcers. If any of these develop, you need a blood test immediately.
Radioactive Iodine Therapy
Radioactive iodine (RAI) is the most common definitive treatment for hyperthyroidism in the United States. You swallow a single capsule or liquid dose of radioactive iodine, which the thyroid absorbs because the gland naturally concentrates iodine from the bloodstream. Once inside the thyroid cells, the radiation gradually destroys them over several weeks to months, shrinking the gland and reducing hormone output.
Cure rates after a single dose range from 80% to 100%. In one study, 87.7% of patients were cured with one dose: about 70% developed an underactive thyroid (which is actually the intended outcome, since it’s easier to manage), and 18% landed in the normal range. The remaining 12% or so needed additional treatment, whether a second RAI dose, continued medication, or surgery.
The trade-off is straightforward. RAI almost always works, but it usually makes the thyroid permanently underactive. That means you’ll take a daily thyroid hormone replacement pill for the rest of your life. Hormone replacement typically begins within days after treatment, and once your dose is dialed in (which can take a few adjustments over several months), most people feel completely normal.
Dietary Changes Before RAI
Before radioactive iodine treatment, you’ll be asked to follow a low-iodine diet for one to two weeks. The goal is to “starve” your thyroid of iodine so it absorbs the radioactive dose more efficiently. This means avoiding iodized salt, dairy products, eggs, seafood, soy products, and commercially baked goods made with iodine-containing dough conditioners. Restaurant and fast food should be skipped entirely since you can’t verify what type of salt they use. Even some supplements, medications, and food dyes (particularly the red dye found in maraschino cherries) contain iodine and should be paused.
Thyroid Surgery
Surgery to remove the thyroid, called thyroidectomy, is typically reserved for specific situations: a very large goiter that causes pressure symptoms in the neck, thyroid nodules that might be cancerous, hyperthyroidism that can’t be controlled with medication, or cases where radioactive iodine isn’t appropriate. It provides the most immediate and certain resolution, since removing the gland eliminates the source of excess hormones entirely.
Like RAI, surgery results in a permanently underactive thyroid that requires lifelong hormone replacement. The procedure itself carries a few specific risks worth understanding. Up to one-third of patients experience temporarily low calcium levels afterward, because the tiny parathyroid glands sitting behind the thyroid get temporarily disrupted during the operation. This usually resolves on its own within weeks. Permanent damage to these glands, requiring lifelong calcium supplementation, happens in only about 1% to 2% of cases. There is also a small risk of injury to the nerves that control the vocal cords, which can cause hoarseness or voice changes.
Treatment During Pregnancy
Pregnancy requires a more careful approach because antithyroid medications cross the placenta and can affect the developing baby. The strategy shifts depending on the trimester. PTU is the preferred drug during the first trimester because it crosses the placenta less readily than methimazole, reducing the risk of fetal hypothyroidism. Methimazole is specifically avoided early in pregnancy because it has been linked to birth defects including heart abnormalities and kidney malformations.
After the first trimester, the guidelines flip. Doctors typically switch from PTU to methimazole to reduce the mother’s risk of liver damage, which is more common with PTU during prolonged use. Beta blockers can also be used cautiously for symptom control during pregnancy: propranolol and metoprolol are considered safe for short-term use, though atenolol should be avoided.
Radioactive iodine is never used during pregnancy because it would destroy the baby’s developing thyroid. Surgery is possible during pregnancy if absolutely necessary but is generally avoided unless medication fails completely.
Choosing Between Treatments
The decision often comes down to how much uncertainty you’re willing to accept. Antithyroid drugs offer a chance at remission without permanently altering the thyroid, but the odds of relapse are high, especially with Graves’ disease. Radioactive iodine is highly effective with minimal short-term risk, but it almost certainly means taking a replacement hormone daily for life. Surgery provides immediate results and tissue for pathology if there’s any concern about cancer, but it’s the most invasive option and carries surgical risks.
Your age, the underlying cause, the size of your thyroid, the severity of your symptoms, and your personal preferences all play into the decision. In many countries outside the United States, antithyroid drugs are tried first, with RAI or surgery held in reserve for relapses. In the U.S., radioactive iodine has historically been the most popular choice, though medication-first approaches have been gaining ground.