Marked falls in
ciclosporin levels (resulting in transplant rejection in some cases) can occur with a few weeks of starting St John's wort.
It is possible to accommodate this interaction by increasing the
ciclosporin dosage. However, the advice of the CSM in the UK is that patients taking
ciclosporin should avoid or stop taking St John's wort. In the latter situation, the
serum ciclosporin levels should be well monitored. Some evidence suggests that monitoring should continue for up to 2 weeks after stopping the St John's wort.