Methimazole is used to treat overactive thyroid (hyperthyroidism). It works by stopping the thyroid gland from making too much thyroid hormone.
Take this medication by mouth with or without food as directed by your doctor, usually 3 times a day (every 8 hours).
Dosage is based on your medical condition and response to treatment. For children, the dosage is also based on their weight.
Take this medication exactly as directed. Do not increase your dose or take it more often than prescribed. Your condition will not improve faster, and your risk of side effects will increase.
Use this medication regularly to get the most benefit from it. To help you remember, take it at the same times each day. Do not stop taking this medication without consulting your doctor.
Tell your doctor if your condition does not improve or if it worsens.
Stomach upset, nausea, vomiting, or mild rash/itching may occur. If any of these effects persist or worsen, tell your doctor or pharmacist promptly.
Tell your doctor right away if any of these rare but serious side effects occur: yellowing eyes/skin, dark urine, severe stomach/abdominal pain, persistent nausea/vomiting, joint/muscle pain, change in the amount of urine.
This medication may rarely cause very serious blood disorders (such as a low number of red cells, white cells, and platelets), especially during the first few months of treatment. Tell your doctor right away if you develop any of the following symptoms: signs of infection (such as fever, persistent sore throat), easy bruising/bleeding, unusual tiredness.
A very serious allergic reaction to this drug is rare. However, seek immediate medical attention if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.
In the US -
Before taking methimazole, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.
Before using this medication, tell your doctor or pharmacist your medical history, especially of: blood disorders (such as agranulocytosis, thrombocytopenia), liver disease.
Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).
This medication is not recommended for use during the first 3 months of pregnancy. It should be used only when clearly needed during the last 6 months of pregnancy. Discuss the risks and benefits with your doctor. If you are planning pregnancy, become pregnant, or think you may be pregnant, contact your doctor right away.
This medication passes into breast milk. Consult your doctor before breast-feeding.
The effects of some drugs can change if you take other drugs or herbal products at the same time. This can increase your risk for serious side effects or may cause your medications not to work correctly. These drug interactions are possible, but do not always occur. Your doctor or pharmacist can often prevent or manage interactions by changing how you use your medications or by close monitoring.
To help your doctor and pharmacist give you the best care, be sure to tell your doctor and pharmacist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products) before starting treatment with this product. While using this product, do not start, stop, or change the dosage of any other medicines you are using without your doctor's approval.
Some products that may interact with this drug include: "blood thinners" (such as warfarin), digoxin, theophylline.
This document does not contain all possible drug interactions. Keep a list of all the products you use. Share this list with your doctor and pharmacist to lessen your risk for serious medication problems.
If overdose is suspected, contact a poison control center or emergency room right away. US residents can call their local poison control center at 1-800-222-1222. Canada residents can call a provincial poison control center.
Do not share this medication with others.
Laboratory and/or medical tests (such as complete blood counts, liver/thyroid function tests, prothrombin time) should be performed periodically to monitor your progress or check for side effects. Consult your doctor for more details.
If you miss a dose, take it as soon as you remember. If it is near the time of the next dose, skip the missed dose and resume your usual dosing schedule. Do not double the dose to catch up.
Store at room temperature away from light and moisture. Storage temperature ranges differ according to different manufacturers, so consult your pharmacist for more information. Do not store in the bathroom. Keep all medications away from children and pets.
Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company for more details about how to safely discard your product.
Information last revised October 2015. Copyright(c) 2015 First Databank, Inc.
With WebMD's Medicine Cabinet, you can check interactions with drugs.Go to medicine cabinet