AntithyroidPrescription only
Carbimazole
Tablet
Quick Summary
Carbimazole blocks the thyroid from making hormones.
Hyperthyroidism
Medical Uses
Hyperthyroidism: Including Graves' disease.
How it's taken
Take as prescribed; blood tests guide changes.
Your doctor decides the right dose for you and how long to take it.
Your doctor decides the right dose for you. Follow their instructions and the label.
Common Side Effects
Rash and itching
Sometimes.
Nausea
Sometimes.
Joint pain
Rarely.
Interactions
Warfarin
Effect may change.
Critical Warnings
Sore throat, fever or mouth ulcers
Black Box Warning: Can mean very low white cells: stop and get a blood test urgently.
Pregnancy
Another medicine is often preferred early in pregnancy.
Sources and further reading
Last updated 21 October 2026. For more detail, see these trusted health organisations.