An Introduction to Methimazole Side Effects
As with any medicine, side effects are possible with
methimazole (
Tapazole®). However, not everyone who takes the medication will experience problems. In fact, most people tolerate it quite well. If side effects do occur, in most cases, they are minor and either require no treatment or are treated easily by you or your healthcare provider.
(This article covers many, but not all, of the possible side effects with methimazole. Your healthcare provider can discuss a more complete list with you.)
Side Effects of Methimazole to Report
Some methimazole side effects, while occurring infrequently, are potentially serious and should be reported to your healthcare provider. These include but are not limited to:
- Signs of low white blood cells, such as:
- Signs of anemia, such as pale skin and fatigue
- Signs of low blood platelets, such as easy bruising or bleeding
- An unexplained fever (without any infection)
- Signs of inflammation of the blood vessels (vasculitis), such as:
- Weight loss
- Fatigue
- Muscle and joint aches
- Abdominal pain (stomach pain)
- Difficulty breathing
- Skin ulcers
- Signs of kidney inflammation (nephritis), such as water retention and decreased urination
- Signs of liver damage, such as:
- Yellow skin (jaundice) or yellow eyes
- Upper-right abdominal pain
- Loss of appetite
- Itching
- High liver enzymes (found using a blood test)
- Signs of an allergic reaction, including:
- Unexplained rash
- Hives
- Itching
- Unexplained swelling
- Wheezing
- Difficulty breathing or swallowing.