Answer
St John's wort may increase the metabolism of Femoston's oestrogen and progestogen via CYP450 3A4, potentially reducing its effectiveness and changing the uterine bleeding pattern.
Sources for this answer
- Femoston 1/10mg film-coated tabletsExeltis UK Ltd · emc · SmPC §4.5 Interaction with other medicinal products · Version 29Document updated
Sources checked