What is Methimazole?
Methimazole prevents the thyroid gland from producing too much thyroid hormone.
Methimazole is used to treat hyperthyroidism (overactive thyroid). It is also used before thyroid surgery or radioactive iodine treatment.
Methimazole may also be used for other purposes not listed in this medication guide.
What is the most important information I should know about Methimazole?
Do not use methimazole if you are pregnant. It could harm the unborn baby.
Do not take methimazole if you are breast-feeding a baby.
Methimazole can increase your risk of bleeding. If you need to have surgery, tell the surgeon ahead of time that you are using this medication.
Methimazole can lower blood cells that help your body fight infections. This can make it easier for you to bleed from an injury or get sick from being around others who are ill. Your blood may need to be tested often. Visit your doctor regularly.
Do not receive a “live” vaccine while you are being treated with methimazole, and avoid coming into contact with anyone who has recently received a live vaccine. There is a chance that the virus could be passed on to you.
Keep using this medication even if you feel fine or have no symptoms of hyperthyroidism. You may need to keep taking methimazole long term to control your condition. Stopping the medication could cause your symptoms to return.
What should I discuss with my healthcare provider before taking Methimazole?
Do not use this medication if you are allergic to methimazole.
If you have any of these other conditions, you may need a dose adjustment or special tests to safely take this medication:
- liver disease
- a blood cell disorder; or
- a weak immune system
FDA pregnancy category D. Do not use methimazole if you are pregnant. It could harm the unborn baby. Use effective birth control, and tell your doctor if you become pregnant during treatment.
Methimazole can pass into breast milk and may harm a nursing baby. Do not use methimazole if you are breast-feeding a baby.
Methimazole Side Effects
What are the possible side effects of Methimazole?
Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.
Stop using methimazole and call your doctor at once if you have a serious side effect such as:
- fever, chills, sore throat, body aches, flu symptoms
- easy bruising or bleeding, unusual weakness
- blood in your urine or stools
- severe blistering, peeling, and red skin rash; or
- nausea, stomach pain, low fever, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes)
Less serious side effects may include:
- headache, drowsiness, dizziness
- mild nausea, vomiting, or stomach upset
- itching, minor skin rash
- muscle, joint, or nerve pain
- swelling; or
- hair loss
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
Methimazole Interactions
What other drugs affect Methimazole?
Tell your doctor about all other medicines you use, especially:
- theophylline (Theo-Dur, Elixophyllin, Uniphyl, and others)
- a blood thinner such as warfarin (Coumadin)
- digoxin (digitalis, Lanoxin); or
- a beta-blocker such as atenolol (Tenormin, Tenoretic), carvedilol (Coreg), labetalol (Normodyne, Trandate), metoprolol (Lopressor, Toprol), nadolol (Corgard), propranolol (Inderal, InnoPran), sotalol (Betapace), and others
This list is not complete and other drugs may interact with methimazole. Tell your doctor about all medications you use. This includes prescription, over-the-counter, vitamin, and herbal products. Do not start a new medication without telling your doctor.
What should I avoid while taking Methimazole?
Avoid being near people who are sick or have infections. Tell your doctor at once if you develop signs of infection.
Do not receive a “live” vaccine while using methimazole, and avoid coming into contact with anyone who has recently received a live vaccine. There is a chance that the virus could be passed on to you. Live vaccines include measles, mumps, rubella (MMR), oral polio, chickenpox (varicella), BCG (Bacillus Calmette and Guérin), and nasal flu vaccine.
Methimazole Dosage
How should I take Methimazole?
Take exactly as prescribed by your doctor. Do not take in larger or smaller amounts or for longer than recommended. Follow the directions on your prescription label.
Take methimazole with a full glass of water.
Methimazole can be taken with or without food, but you should take it the same way each time.
Methimazole can increase your risk of bleeding. If you need to have any type of surgery, tell the surgeon ahead of time that you are using this medication.
Methimazole can lower blood cells that help your body fight infections. This can make it easier for you to bleed from an injury or get sick from being around others who are ill. Your blood may need to be tested often. Visit your doctor regularly.
It is important to use methimazole regularly to get the most benefit. Get your prescription refilled before you run out of medicine completely.
Keep using this medication even if you feel fine or have no symptoms of hyperthyroidism. You may need to keep taking methimazole long term to control your condition. Stopping the medication could cause your symptoms to return.
Store at room temperature away from moisture and heat.
What happens if I overdose on Methimazole?
Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.
Overdose symptoms may include nausea, vomiting, upset stomach, headache, joint pain, fever, itching, swelling, or pale skin and easy bruising or bleeding.
What happens if I miss a dose of Methimazole?
Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.
Edited from everydayhealth.com