Side effects of carbimazole and their estimated frequency3 39
| Side effects | Frequency |
| Mild | |
| Skin Rash | Common* |
| Joint pain/swelling | Common* |
| Headache | Rare† |
| Hair loss | Rare† |
| Gastrointestinal disturbances | Rare† |
| Severe | |
| Agranulocytosis | Rare† |
| Cholestatic jaundice | Very rare‡ |
| Aplastic anaemia | Very rare‡ |
| Antineutrophil cytoplasmic antibodies (ANCA) positive vasculitis | Very rare‡ |
*Side effects are relatively common 1%–11%.
†Rare 0.1%–1% .
‡Very rare <0.1%.