Adverse Drug Interactions With St. John's Wort
compiled by: Eric Brandt, B.Sc. Pharm
St. John's Wort when used concurrently with some prescription medications can have an adverse effect of the action of the prescription medication.
Here are a few examples.
- can decrease serum concentration of the anti-rejection drug Cyclosporine. This can contribute to transplant rejection.
- can lower the INR in patients taking the anticoagulant Warfarin.
- can reduce serum concentration of Indinavir- a drug used to treat HIV infected patients.
- can reduce the serum concentration of Digoxin
- women taking St. John's Wort and oral contraceptives have reported breakthrough bleeding, but not unexpected pregnancies.
- can lower serum concentration of theophylline.
- can lower serum concentration of amitriptyline.
- can increase toxicity of selective serotonin reuptake inhibitor antidepressants such as paroxetine and fluoxetine.
- can increase toxicity of the antidepressant nefazodone.
References available on request.