Herbs: Toxicities And Drug Interactions (cont.)

Medical Author:

William C. Shiel Jr., MD, FACP, FACR

William C. Shiel Jr., MD, FACP, FACR

Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

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Medical Editor:

Melissa Conrad Stöppler, MD

Melissa Conrad Stöppler, MD

Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

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Reactions: The most common side effect has been sun sensitivity which causes burning of the skin. It is recommended that fair-skinned persons be particularly careful while in the sun. St. John's wort may also leave nerve changes in sunburned areas. This herb should be avoided in combination with other medications that can affect sun sensitivity [such as tetracycline/Achromycin, sulfa- containing medications,  piroxicam (Feldene)]. St. John's wort can also cause headaches, dizziness, sweating, and agitation when used in combination with serotonin reuptake inhibitor medications (SSRIs) such as fluoxetine (Prozac) and paroxetine (Paxil).

Garlic

Uses: Garlic has been used to lower blood pressure and cholesterol (Dr. Lucinda Miller notes that there is "...still insufficient evidence to recommend its routine use in clinical practice.")

Reactions: Allergic reactions, skin inflammation, and stomach upset have been reported. Bad breath is a notorious accompaniment. Studies in rats have shown decreases in male rats' ability to make sperm cells. Garlic may decrease normal blood clotting and should be used with caution in patients taking medications to prevent blood clotting (anticoagulants) such as warfarin (Coumadin).

Feverfew

Uses: Most commonly used for migraine headaches.

Reactions: Feverfew can cause allergic reactions, especially in persons who are allergic to chamomile, ragweed, or yarrow. Nonsteroidal anti-inflammatory drugs [NSAIDs such as ibuprofen (Advil), naproxen (Aleve) or Motrin] can reduce the effect of feverfew. A condition called "post-feverfew syndrome" features symptoms including headaches, nervousness, insomnia, stiffness, joint pain, tiredness, and nervousness. Feverfew can impair the action of the normal blood clotting element (platelets). It should be avoided in patients taking medications to prevent blood clotting (anticoagulants) such as warfarin (Coumadin).

Ginkgo Biloba

Uses: This herb is very popular as a treatment for dementia (a progressive brain dysfunction) and to improve thinking.

Reactions: Mild stomach upset and headache have been reported. Ginkgo seems to have blood thinning properties. Therefore, it is not recommended to be taken with aspirin, nonsteroidal anti-inflammatory drugs [such as ibuprofen (Advil),  naproxen (Aleve) or Motrin], or medications to prevent blood clotting (anticoagulants) such as warfarin (Coumadin). Ginkgo should be avoided in patients with epilepsy taking seizure medicines, such as phenytoin  (Dilantin), carbamazepine (Tegretol), and phenobarbital.

Ginseng

Uses: Ginseng has been used to stimulate the adrenal gland, and thereby increase energy. It also may have some beneficial effect on reducing blood sugar in patients with diabetes mellitus. (Dr. Miller emphasized that there is substantial variation in the chemical components of substances branded as "Ginseng.")

Reactions: Ginseng can cause elevation in blood pressure, headache, vomiting, insomnia, and nose bleeding. Ginseng can also cause falsely abnormal blood tests for digoxin (Lanoxin) levels in persons taking the drug for heart disease. It is unclear whether ginseng may affect female hormones. Its use in pregnancy is not recommended. Ginseng may affect the action of the normal blood clotting element (platelets). It should be avoided in patients taking aspirin, nonsteroidal antiinflammatory drugs [such as ibuprofen (Advil), naproxen (Aleve) or Motrin], or medications to prevent blood clotting (anticoagulants) such as warfarin (Coumadin). Ginseng may also cause headaches, tremors, nervousness, and sleeplessness. It should be avoided in persons with manic disorder and psychosis.