Uses

Methimazole is used to treat overactive thyroid (hyperthyroidism). It works by stopping the thyroid gland from making too much thyroid hormone.

How To Use

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.

Side Effects

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.

Remember that this medication has been prescribed because your doctor has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.

Tell your doctor right away if you have any serious side effects, including:

• joint/muscle pain
• numb/tingling skin
• shortness of breath
• coughing up blood
• signs of liver problems (such as nausea/vomiting that doesn't stop, yellowing eyes/skin, dark urine, severe stomach/abdominal pain)
• signs of kidney problems (such as change in the amount of urine, bloody 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 sore throat that doesn't go away, fever)
• easy bruising/bleeding
• unusual tiredness

A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including:

• rash
• itching/swelling (especially of the face/tongue/throat)
• severe dizziness
• trouble breathing

This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.

In the US -

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.

In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

Precautions

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
• pancreatitis

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. 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.

Drug Interactions

Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.

Some products that may interact with this drug include:

• "blood thinners" (such as warfarin)
• digoxin

Overdose

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. Alberta residents can call PADIS (Poison and Drug Information Service) 24 hours a day at 1-800-332-1414. Canada residents can call a provincial poison control center.

Notes

Do not share this medication with others.

Lab and/or medical tests (such as complete blood counts, liver/thyroid function, prothrombin time) should be done while you are taking this medication. Keep all medical and lab appointments. Consult your doctor for more details.

Missed Dose

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.

If you have questions about missing a dose or you don't have more medication, contact your healthcare provider or pharmacist.

Storage

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.