Worry Wort
For: Wellness Made Easy, April 2002
Millions of Americans take St. John's wort for
depression, anxiety, or insomnia. Most of them assume that this
herb and "dietary supplement" is perfectly safe, unlike
conventional antidepressants, which often have side effects. It's
not a "drug," so they think St. John's wort is harmless.
As we've reported, however, herbs can be powerful substances
and have side effects. That's why it's important to tell
your doctor if you're taking St. John's wort (or other
herbs), especially if you take prescription medication.
Several recent studies have pointed out dangerous
interactions between St. John's wort and other medications:
• The herb can reduce blood levels of an important HIV drug (indinivir) by more than half. As a result, the body may clear the drug before it has time to work fully; low blood levels of indinivir can lead to drug-resistant virus. St. John's wort may also affect other HIV drugs that are similarly metabolized by the body. Many people with HIV take herbs, especially St. John's wort.
• It reduces the effect of the blood thinner warfarin (brand name Coumadin).
• It reduces the effect of the heart drug digoxin.
• It reduces the effect of cyclosporin, which helps prevent organ rejection in people given transplants.
• It may interact with some oral contraceptives (OCs) to cause breakthrough menstrual bleeding and may reduce the effectiveness of OCs in preventing pregnancy. Talk to your doctor if you are on the Pill and want to take this herb.
• Older people taking prescription antidepressants (Prozac-like drugs) and St. John's wort suffered dizziness, confusion, headaches, and anxiety, according to one study. The elderly are particularly susceptible to this interaction, the symptoms of which are often misdiagnosed as worsening psychiatric symptoms or a neurologic disorder. But younger people also should not combine the herb with conventional antidepressants.
St. John's wort contains at least 10 compounds
that can have pharmacological action. Some of these are known to
directly affect the way the liver metabolizes drugs, which can result
in blood levels of these drugs that are too high or too low. But
since these compounds are not standardized, and people take such
a wide range of dosages, the interactions are often unpredictable.
Further news: If you take St. John's wort and
are going to receive anesthesia, make sure your anesthesiologist
knows. The herb can intensify or prolong the effect of some anesthetic
agents.
UC Berkeley Wellness Letter, September 2001
