Methimazole is a drug used to treat hyperthyroidism, which is a condition where high levels of thyroid hormone are present. One of the causes of hyperthyroidism is Graves (Graves' disease). This drug can also be used before the patient has thyroid surgery or radioactive iodine therapy.
Methimazole belongs to the class of antithyroid drugs. This drug works by blocking the work of the thyroid gland in producing thyroid hormone. That way, thyroid hormone levels can decrease and symptoms of hyperthyroidism, such as heart palpitations or tremors, can subside.
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What is Methimazole
| group | Prescription drugs |
| Category | Antithyroid |
| Benefit | Overcoming hyperthyroidism |
| Consumed by | Adults and children |
| Methimazole for pregnant and lactating women | Category D: There is positive evidence of risks to the human fetus, but the benefits may outweigh the risks, for example in dealing with life-threatening situations. Methimazole may be absorbed into breast milk. If you are breastfeeding, do not use this medicine without consulting your doctor first. |
| Drug form | Tablet |
Warnings Before Taking Methimazole
There are several things you should pay attention to before taking methimazole, including:
- Tell your doctor about any allergies you have. Methimazole should not be used by patients who are allergic to this drug.
- Tell your doctor if you have or have had liver disease, a weakened immune system, pancreatitis, blood disorders, such as angranulocytosis or aplastic anemia.
- Tell your doctor if you are pregnant, breastfeeding, or planning a pregnancy.
- If you are planning to have surgery or certain medical procedures, tell your doctor that you are taking methimazole.
- Tell your doctor if you are taking certain medications, supplements, or herbal products.
- See your doctor right away if you have an allergic drug reaction, serious side effect, or overdose after taking methimazole.
Dosage and Instructions for Use of Methimazole
The dose of methimazole varies in each patient. The doctor will adjust the dose according to the patient's age and health condition. Here is the explanation:
Condition: Hyperthyroidism
- Mature: For mild hyperthyroidism the dose is 15 mg per day in 3 divided doses. For moderate hyperthyroidism the dose is 30-40 mg per day in 3 divided doses. For severe conditions the dose is 60 mg per day divided into 3 doses. The maintenance dose is 5–30 mg per day in 3 divided doses.
- Children: Initial dose 0.5–0.7 mg/kgBW per day in 3 divided doses. Maintenance 0.2 mg/kgBW per day in 3 divided doses.
Condition: Graves' disease
- Mature: 10–20 mg per day. The dose can be reduced to 50% of the initial dose when thyroid hormone levels return to normal. Treatment can be done for 12-18 months.
How to Take Methimazole Correctly
Take methimazole as directed by your doctor and always read the instructions for use listed on the drug packaging. Do not reduce or increase the dose without consulting your doctor first.
Methimazole should be taken with food to reduce the effects of nausea. Use plain water to swallow the tablet.
If you forget to take methimazole, take it as soon as you remember. If it is near the time of your next dose, ignore the missed dose. Do not double the dose of methimazole to make up for a missed dose.
Store methimazole at room temperature and store in a closed container. Keep the medicine away from direct sunlight and out of reach of children.
Methimazole Interactions with Other Drugs
The following are some interactions that may occur if methimazole is used together with other medicines:
- Increased risk of bleeding if taken with anticoagulant drugs, such as warfarin
- Increases risk of liver problems if used with teriflunomide, pexdartinib, or lopitamide
- Decreases the effectiveness of beta-blocking drugs, such as atenolol, sotalol, or labetalol
- Increase the levels of theophylline or digoxin in the blood
Side Effects and Dangers of Methimazole
Some of the side effects that can occur after taking methimazole are:
- Muscle pain and joint pain
- The appearance of a rash on the skin
- Hair loss
- Headache, dizziness, or drowsiness
- Nausea and vomiting
- Stomach ache
- tingling
- Loss of ability to taste
Check with a doctor if the complaints mentioned above do not go away or get worse. See your doctor right away if you have an allergic reaction to a drug or experience more serious side effects, such as:
- Headaches that get worse or vertigo that doesn't go away
- Coughing up blood or difficulty breathing
- Kidney disorders, which can be characterized by infrequent urination or very small amounts of urine
- Decreased production of blood cells which can increase the risk of infectious diseases or anemia
- Impaired liver function, which can be characterized by complaints of jaundice, dark urine, severe abdominal pain, or severe and persistent nausea and vomiting