St John's wort (Hypericum perforatum) decreased methadone levels by up to 60% in one study, and withdrawal
symptoms have been reported. Some herbal teas may contain
opioids such as morphine.
Advise patients taking methadone to avoid St John's wort. Additive
CNS depressant effects may occur if herbal teas containing
opioids are taken with prescribed opioid preparations.