Pharmacokinetic interaction
St John's wort preparations induce the activity of the enzymes of the cytochrome P 450 system. This may lead to a weakening and / or shortening of the duration of the clinical effect of the coumarinic anticoagulants (for example, fenprocumone, warfarin), immunosuppressants (eg, ciclosporin, sirolimus, tacrolimus), digoxin, indinavir and other protease inhibitors used to treat HIV, irinotecan and other cytotoxic agents, amitriptyline, midazolam, theophylline.
In women with simultaneous application of St. John's wort with low-dose hormonal contraceptives, intermenstrual bleeding is possible.
Pharmacodynamic interaction
With simultaneous application of St. John's wort with a number of antidepressants (nefazodone, paroxetine, sertraline) the pharmacological effect of the latter can be strengthened. In some cases, unwanted (serotonergic) effects may increase, such as nausea, vomiting, a sense of fear, restlessness, confusion.
It is theoretically possible to enhance the phototoxic effect of St. John's wort, when combined with photosensitizing preparations.
The simultaneous application of St. John's wort with cyclosporine, sirolimus, tacrolimus or indinavir and other protease inhibitors used for HIV treatment, irinotecan and other cytostatics, as well as antidepressants is not recommended (see "Contraindications").
In all cases where other medicines are prescribed, it is necessary to consult a doctor.