Grison Griseofulvin Levonorgestrel [For emergency contraception]
ModerateGriseofulvin may make Levonorgestrel [for emergency contraception] work less well, or stop it working at all. If you take the two together, the emergency contraception may not prevent pregnancy as it should. Other medicines can do the same, including phenobarbitone, phenytoin, primidone, carbamazepine and rifampicin.
These medicines are often taken together with some care. Your doctor may change a dose, space them apart or check on you more often. Make sure your doctor and pharmacist know you take both.