What are Herb-Drug Interactions?

Article Details
  • Written By: wiseGEEK Writer
  • Edited By: O. Wallace
  • Last Modified Date: 28 May 2019
  • Copyright Protected:
    Conjecture Corporation
  • Print this Article

Herb-drug interactions are generally adverse reactions that occur when people combine certain herbal medicines with more traditional prescribed or over the counter medicines. This potentially dangerous practice is frequently overlooked by people who take herbs because they see these as benign replacements to “prescribed” and chemically-oriented drugs. Such a point of view is particularly dangerous, especially with certain herb-drug interactions, and anybody who takes more than one drug, be it chemical or herbal in nature, should not be complacent. Talking with a pharmacist or a doctor prescribing medicine is the best way to determine no dangerous interactions occur.

Sometimes herb-drug interactions have a synergistic effect, which means they work together to enhance the action of at least one of the medicines. This is especially true when herbs and drugs used are for the same basic purpose. Taking herbs like kava kava or valerian is common to treat anxiety.

It is not advisable to, at the same, time take prescription drugs that have the same effect. Blending valerian and Xanax®, for example, might create a much higher level of sedation. Even adding an over the counter antihistamine like diphenhydramine (Bendaryl®) may suppress the respiratory system to a certain degree or cause extreme drowsiness. Amounts taken may greatly increase herb-drug interactions and be highly dangerous.


One drug that interacts with many herbs is warfarin (Coumadin®). It also interacts with numerous other prescription drugs and foods. People need to be very cautions before using any type of herbs with warfarin, and especially any type of herbal preparations that may have a blood-thinning effect. An herb like feverfew, which is often used for strong headaches or for its anticoagulant effect is absolutely contraindicated if a person takes warfarin or other blood thinners like aspirin. Other herbs such ginkgo biloba, licorice, garlic and ginseng, may either increase blood thinning or decrease the efficacy of warfarin and are not advised.

Another example of how herb-drug interactions can be dangerous occurs when people use herbal and prescribed antidepressants concurrently. St. John’s Wort, bears strong relationship to a group of antidepressants called monoamine oxidase inhibitors (MAOIs). People should never double up on herbal and prescribed MAOIs, as this may cause extreme illness. Additionally, using St. John’s Wort is contraindicated for people using oral birth control because it may lower protection from unwanted pregnancy: a very serious consideration.

What herb-drug interactions truly say is that herbs have to be respected as real medicine. Unfortunately they are not given the same kind of scrutiny in many countries as are prescription drugs, and people may view them as somehow less potent or less capable of both healing and damage as chemically produced drugs. It might be more useful to understand that herbs and drugs really are all drugs, and safely using them means getting medical assistance when deciding which of these drugs are combined without ill effects.



Discuss this Article

Post your comments

Post Anonymously


forgot password?