Methimazole - oral
Methimazole - oral
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 1 to 3 times a day.
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 time(s) 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 last or get worse, tell your doctor or pharmacist promptly.
Tell your doctor right away if you have any serious side effects, including:
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:
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:
This medication is not recommended for use during the first 3 months of pregnancy. Your doctor may direct you to use another medication during that time. 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.
Some products that may interact with this drug include:
If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center 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. Take your next dose at the regular time. 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.
Information last revised April 2020.
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