HERBAL MEDICINES OR DIETARY SUPPLEMENTS AND PHENYTOIN - ST JOHN'S WORT (HYPERICUM PERFORATUM)
St John's wort is predicted to reduce the blood levels of phenytoin. Fosphenytoin, a prodrug of phenytoin, may interact similarly.
The CSM in the UK advise that St John's wort should be stopped and that the phenytoin dosage should be adjusted. However, note that this prediction also covered carbamazepine, which has subsequently been found not to interact, so a clinically significant interaction with phenytoin now seems less likely.
The CSM in the UK advise that St John's wort should be stopped and that the phenytoin dosage should be adjusted. However, note that this prediction also covered carbamazepine, which has subsequently been found not to interact, so a clinically significant interaction with phenytoin now seems less likely.