Methimazole is used to treat hyperthyroidism, a condition that occurs when the thyroid gland produces too much thyroid hormone. It is also taken before thyroid surgery or radioactive iodine therapy.

This medication is sometimes prescribed for other uses; ask your doctor or pharmacist for more information.

Methimazole comes as a tablet and usually is taken three times a day, approximately every 8 hours, with food. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand.

Before taking methimazole,

• tell your doctor and pharmacist if you are allergic to methimazol, lactose, or any other drugs.
• tell your doctor and pharmacist what prescription and nonprescription medications you are taking, especially anticoagulants (‘blood thinners’) such as warfarin (Coumadin), beta blockers such as propranolol (Inderal), diabetes medications, digoxin (Lanoxin), theophylline (Theobid, Theo-Dur), and vitamins.
• tell your doctor if you have or have ever had any blood disease, such as decreased white blood cells (leukopenia), decreased platelets (thrombocytopenia), or aplastic anemia, or liver disease (hepatitis, jaundice).
• tell your doctor if you are pregnant, plan to become pregnant, or are breast-feeding. Methimazole should not be used during pregnancy or breast-feeding. If you become pregnant while taking methimazole, call your doctor immediately. Methimazole may harm the fetus.
• if you are having surgery, including dental surgery, tell the doctor or dentist that you are taking methimazole.

Methimazole may cause an upset stomach. Take methimazole with food or milk.

Take the missed dose as soon as you remember it. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule at evenly spaced, 8-hour intervals. Do not take a double dose to make up for a missed one.

Methimazole may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

• skin rash
• itching
• abnormal hair loss
• upset stomach
• vomiting
• loss of taste
• abnormal sensations (tingling, prickling, burning, tightness, and pulling)
• swelling
• joint and muscle pain
• drowsiness
• dizziness
• decreased white blood cells
• decreased platelets

If you experience any of the following symptoms, call your doctor immediately:

• sore throat
• fever
• headache
• chills
• unusual bleeding or bruising
• right-sided abdominal pain with decreased appetite
• yellowing of the skin or eyes
• skin eruptions

If you experience a serious side effect, you or your doctor may send a report to the Food and Drug Administration’s (FDA) MedWatch Adverse Event Reporting program online (http://www.fda.gov/Safety/MedWatch) or by phone (1-800-332-1088).

Keep this medication in the container it came in, tightly closed, and out of reach of children. Store it at room temperature and away from excess heat and moisture (not in the bathroom).

Unneeded medications should be disposed of in special ways to ensure that pets, children, and other people cannot consume them. However, you should not flush this medication down the toilet. Instead, the best way to dispose of your medication is through a medicine take-back program. Talk to your pharmacist or contact your local garbage/recycling department to learn about take-back programs in your community. See the FDA’s Safe Disposal of Medicines website (http://goo.gl/c4Rm4p) for more information if you do not have access to a take-back program.

It is important to keep all medication out of sight and reach of children as many containers (such as weekly pill minders and those for eye drops, creams, patches, and inhalers) are not child-resistant and young children can open them easily. To protect young children from poisoning, always lock safety caps and immediately place the medication in a safe location – one that is up and away and out of their sight and reach. http://www.upandaway.org

In case of overdose, call the poison control helpline at 1-800-222-1222. Information is also available online at https://www.poisonhelp.org/help. If the victim has collapsed, had a seizure, has trouble breathing, or can’t be awakened, immediately call emergency services at 911.

Keep all appointments with your doctor and the laboratory.

Do not let anyone else take your medication. Ask your pharmacist any questions you have about refilling your prescription.

It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.