Herbal ingredient St John鈥檚 wort may interact with antiepileptics
Patients with epilepsy should not take products that contain St John鈥檚 wort as any antiepileptic medicine may interact with St John鈥檚 wort.
Article date: November 2007
St John鈥檚 wort (hypericum perforatum) is a herbal ingredient commonly available in the UK as an unlicensed herbal medicine.
Traditionally, St John鈥檚 wort has had various uses, including external application as a treatment for wounds and burns; it is also taken orally to treat fevers and conditions such as depression.
In 2000, warnings were issued that some antiepileptic medicines interacted with St John鈥檚 wort. These warnings were based on the metabolism of these medicines and the known induction and inhibitory effects of St John鈥檚 wort on various cytochrome P450 enzymes.
MHRA continues to receive reports of possible interactions with St John鈥檚 wort through the . A recent case involved St John鈥檚 wort and several different antiepileptic medicines, which resulted in an increase in the frequency and severity of the patient鈥檚 seizures. The antiepileptic medicines the patient was taking (levetiracetam, lamotrigine, and clobazam) were not those previously known to interact with St John鈥檚 wort.
and have considered the interaction between St John鈥檚 wort and antiepileptic medicines by routes other than the recognised cytochrome P450 pathway. Both have recommended that the current warnings about interactions should extend to include all antiepileptic medicines.
Advice for healthcare professionals includes:
- concomitant use of St John鈥檚 wort and antiepileptic medicine is not recommended: healthcare professionals should advise patients with epilepsy not to use products that contain St John鈥檚 wort
- continue to report any suspected adverse reaction with St John鈥檚 wort, or any other herbal medicines, through the
See .
Article citation: Drug Safety Update November 2007, vol 1 issue 4: 7.