St. John's wort interacts with a range of medications. In most cases, this
interactions leads to reduced the effectiveness of the medication in question;
in other cases, however, St. John's wort may increase the effects of a
If you are currently being treated with any of the following medications, you
should not use St. John's wort without first talking to your healthcare
St. John's wort may interact with
antidepressant medications that are used to treat depression or other mood
disorders, including tricyclics, SSRIs (see earlier discussion), and monoamine
oxidase inhibitors (MAOIs) such as phenelzine. How St. John's wort works is not
entirely clear, but is believed to be similar to how SSRIs work. Therefore,
using St. John's wort with this class of antidepressants in particular can lead
to exacerbation of side effects including headache, dizziness, nausea,
agitation, anxiety, lethargy, and lack of coherence.
St. John's wort should not be taken by those on
digoxin because the herb may decrease levels of the medication and reduce its
St. John's wort should not be
taken by those on immunosuppressive medications such as cyclosporine because it
may reduce the effectiveness of these medications. In fact, there have been many
reports of cyclosporin blood levels dropping in those with a heart or kidney
transplant, even leading to rejection of the transplanted organ.
Indinavir and other protease inhibitors
The Food and Drug
Administration (FDA) issued a public health advisory in February 2000 concerning
the probable interaction between indinavir and St. John's wort that resulted in
significantly decreased blood levels of this protease inhibitor, a class of
medications used to treat HIV or AIDS. The FDA recommends that St. John's wort
not be used with any type of antiretroviral medication used to treat HIV or
There has been a report of a possible interaction
between St. John's wort and the antidiarrheal medication, loperamide leading to
delirium in an otherwise healthy woman.
There have been reports of breakthough
bleeding in women on birth control pills who were also taking St. John's
Based on animal studies, St. John's wort may
interfere with the intended action of this medication used to treat high blood
St. John's wort can reduce levels of this
medication in the blood leading. Theophylline is used to open the airways in
those suffering from asthma, emphysema, or chronic bronchitis.
St. John's wort interferes with the anticoagulant
medication, warfarin, by reducing blood levels as well as the effectiveness.
This leads to the need to for adjustments in doses of this