The manufacturers of
sirolimus predict that
St John's wort (Hypericum perforatum) may lower its
serum levels, probably because rifampicin (
rifampin), another CYP3A4 inducer, has been shown to do so.
The extent of any change in
sirolimus levels is uncertain, but if concurrent use cannot be avoided it would seem prudent to increase the frequency of monitoring of
sirolimus levels.