About carbimazole
Antithyroid medicine
Used for
- Treats an overactive thyroid (hyperthyroidism)
- Helps prepare for thyroid surgery or radioactive iodine treatment
Usual adult dose
Usually 15–40 mg daily initially, adjusted to thyroid blood tests; maintenance is often 5–15 mg daily.
Usual dose in children
Specialist-directed; commonly 0.25–0.5 mg/kg daily initially, adjusted to response.
Common side effects
- Nausea, stomach upset, or headache
- Rash, itching, or joint pain
- Reduced white blood cells, which can cause serious infection
- Rare liver problems or inflammation of the pancreas
Important warnings
- Fever, sore throat, mouth ulcers, or unusual bruising may signal dangerously low blood cells.
- Seek urgent medical assessment for jaundice, dark urine, or severe abdominal pain.
- Do not stop or change treatment without clinical guidance.
- Regular thyroid blood tests are needed; dose depends on results.
Pregnancy
Can harm the unborn baby, especially early in pregnancy. Use only when needed under specialist supervision; treatment may need adjustment.
Breastfeeding
May be used during breastfeeding at the lowest effective dose under medical supervision; monitoring may be recommended.
Interactions
- Warfarin effects may change as thyroid levels normalize.
- Theophylline levels may rise as thyroid function changes.
- Other medicines affecting blood cells can increase risk of blood disorders.
- Tell clinicians about all medicines, including iodine-containing products.
AI-generated from general medical knowledge, not from this product's official leaflet. It may be incomplete or out of date. Not medical advice — ask a pharmacist or doctor before making any decision.