Deadly combos: taking prescription drugs and herbs together can be risky for your health. Here's what not to mix

Shape, March, 2005 by Mary Jane Horton

If you use popular herbal supplements, such as Saint Johnswort, echinacea or even garlic, take note: Combining them with prescription medications may threaten your health, according to recent studies. Drug/herb interactions can interfere with the effectiveness of everything from birth-control pills to antibiotics, and can even cause uncontrolled bleeding, liver damage and death. "People think herbs are 'natural,' so they must be safe. But that isn't always true, especially when they are combined with other substances," says Brent A. Bauer, M.D., director of the Complementary and Integrative Medicine Program at the Mayo Clinic in Rochester, Minn.

"We are just starting to learn about these interactions," Bauer says. "However, much of the information is theoretical, based on what we know about the actions of the drugs and the actions of the herbs."

The chart below details what we do know. For more information on herb-drug interactions, visit mayoclinic.com, herbmed.org and nccam.nih.gov.

HERB OR SUPPLEMENT    WHAT IT'S FOR           POTENTIAL INTERACTIONS

* DONG QUAI, an herb  Easing discomfort       Increased risk of
                      associated with         uncontrolled bleeding when
                      premenstrual syndrome,  combined with warfarin
                      menstrual cramps and    (Coumadin)--a blood-
                      menopausal symptoms     thinning medication. When
                                              taken with Saint Johnswort
                                              or certain antibiotics
                                              (Bactrim, Septra), it may
                                              increase your skin's
                                              sensitivity to sun.
* ECHINACEA, an herb  Boosting immune system  May cause liver damage if
                                              taken with anabolic
                                              steroids or hormone
                                              precursors (DHEA),
                                              benzodiazepines (Valium),
                                              calcium channel blockers
                                              (Calan) or HIV protease
                                              inhibitors (Agenerase).
                                              Also may interfere with
                                              immunosuppressant
                                              medications, such as
                                              ciclosporin, for organ-
                                              transplant patients.
* GARLIC, as a        Lowering cholesterol    Some preliminary studies
supplement                                    show that combining garlic
                                              supplements with warfarin,
                                              aspirin and other blood-
                                              thinning medications may
                                              cause spontaneous, heavy
                                              bleeding. One small study
                                              also suggests that garlic
                                              may decrease the
                                              effectiveness of
                                              immunosuppressant
                                              medications. It also may
                                              cause a drop in blood
                                              sugar, so diabetics should
                                              check levels carefully.
* GINGKO BILOBA,      Improving memory,       May cause uncontrolled
an herb               concentration; easing   bleeding when taken with
                      symptoms of depression  blood-thinning
                                              medications. Also may
                                              increase prescription
                                              anti-depressant levels in
                                              the blood. May affect
                                              insulin levels, so
                                              diabetics should be
                                              especially cautious.
* KAVA, an herb       Relaxation, sleep       Can cause liver damage and
                                              coma when taken with
                                              sedatives, sleeping pills
                                              (Ambien), anti-psychotic
                                              medications (Thorazine),
                                              alcohol and drugs used to
                                              treat Parkinson's disease.
* SAM-E, a dietary    Easing symptoms of      When taken with SSRI anti-
supplement            depression              depressants (Prozac,
                                              Zoloft) there is a small
                                              risk of serotonin
                                              syndrome, dangerously high
                                              serotonin levels that can
                                              cause headache, upset
                                              stomach, restlessness and
                                              even coma.
* SAINT JOHNSWORT,    Easing symptoms of      Weakens the effectiveness
an herb               depression              of antibiotics and birth-
                                              control pills. Especially
                                              dangerous when taken with
                                              cancer drugs tamoxifen
                                              citrate (Nolvadex) or
                                              imatinib mesylate
                                              (Gleevec); digoxin
                                              (Lanoxin), a heart
                                              medication; and
                                              immunosuppressant
                                              medication. It may cause
                                              serotonin syndrome if
                                              taken with SSRI anti-
                                              depressants.