MedicinePOMEssential

Carbimazole

A tablet that treats an overactive thyroid by reducing thyroid hormones.

Clinical information

Common uses

overactive thyroid (hyperthyroidism)

Common side effects

feeling or being sick
feeling dizzy
headaches
painful joints
itchy or mild rash

Cautions

rare drop in white blood cells — report sore throat or fever urgently
regular blood tests needed before and during treatment
can cause liver problems — watch for yellowing skin or eyes
use reliable contraception; extra monitoring if pregnant

Interactions

digoxin (heart medicine)
erythromycin (antibiotic)
theophylline (breathing medicine)
warfarin and other anticoagulants
steroids such as prednisolone
clozapine (antipsychotic)

Pregnancy: not often recommended — usually switched to propylthiouracil

Reference information, not medical advice — always follow your doctor or pharmacist. Source: NHS Medicines A–Z, nhs.uk/medicines/carbimazole (accessed 2026-08-16)

Approved brands & formulations4

Brand name	Dosage form	Strength	Importer	Category
Carbimazole	Tablet	10mg	—	POM
Carbimazole	Tablet	5 mg	—	POM
Neo Mercazole 10	Tablet	10mg	—	POM
Neo Mercazole 5	Tablet	5mg	—	POM