Carbimazole
Also sold as: Neo-Mercazole
Prescription neededThyroid medicines
Comes as:Tablet
Usual adult dose
Dose is set by your doctor; a usual starting dose is 15 to 40 mg a day, then lowered to 5 to 15 mg a day once thyroid levels are normal. Treatment often lasts 12 to 18 months with regular blood tests.
Your doctor may give you a different dose. Children's doses depend on weight.
Side effects
Common
- nausea
- headache
- itching or rash
- joint pain
- change in taste
Serious — get help
Stop taking it and see a doctor straight away if you notice:
- sore throat
- fever or mouth ulcers (stop and get a blood test urgently — may be low white cells)
- yellow eyes or skin
Do not take it, or take care, if
- Previous serious blood or liver reaction to carbimazole or thiamazole
- First 3 months of pregnancy (propylthiouracil is usually preferred)
- Breastfeeding (use only the lowest dose with a doctor)
Interactions
Medicines that can react with this one.
Moderate1 medicineTake together only with care. Ask your doctor or pharmacist.
- Warfarin
As the thyroid returns to normal, the effect of warfarin can change; INR should be checked.
Minor1 medicineUsually not a problem, but tell your doctor.
- Digoxin
Digoxin levels can rise as thyroid levels fall; the dose may need adjusting.