Drug-Herb Interactions

Drug-Herb interactions are, in my opinion, greatly misunderstood. Part of that misunderstanding comes from the fact that herbs themselves are misunderstood — they are viewed alternately as having little or no effect (power) at all and, conversely (and contradictorily), as horribly dangerous.

Invariably, when there are drug-herb interactions it’s the herb that gets fingered as the culprit, not the inherently dangerous drug whose effects or side effects have been exacerbated. What’s wrong with this picture?

What actually happens between drugs and the few herbs that adversely affect them?

The following excerpt explains very nicely just what happens when herbs and pharmaceuticals interact to create adverse conditions:

…the nature of herb-drug interactions is not a chemical interaction between a drug and an herb component to produce something toxic. [Emphasis added.]  Instead, the interaction may involve having an herb component cause either an increase or decrease in the amount of drug in the blood stream. A decrease in the amount of drug could occur by herb components binding up the drug and preventing it from getting into the blood stream from the gastrointestinal tract, or by stimulating the production and activity of enzymes that degrade the drug and prepare it for elimination from the body. An increase in the drug dosage could occur when an herb component aids absorption of the drug, or inhibits the enzymes that break down the drug and prepare it for elimination. A decrease in drug dosage by virtue of an interaction could make the drug ineffective; an increase in drug dosage could make it reach levels that produce side effects. Alternatively, an herb might produce an effect that is contrary to the effect desired for the drug, thereby reducing the drug effect; or, an herb might produce the same kind of effect as the drug and give an increase in the drug effect (without increasing the amount of the drug). Examples of concerns about herb-drug interactions that have been raised are that an herb might:

* increase or decrease the effect of a blood thinner such as Warfarin and lead to either a bleeding episode or formation of a dangerous clot;

* decrease the effect of a blood pressure medication, leading to high blood pressure and a stroke;

* decrease the effect of an anti-infection agent, letting the infection get out of control; or

* increase the effect of an anti-diabetes drug and plunge blood sugar to dangerously low levels.

Such responses can occur with drug-drug interactions and with food-drug interactions, so the finding of some instances of herb-drug interaction would not be surprising.

For the most part, commercially available herbs are NOT dangerous when used properly — and by properly I mean knowledgeably and respectfully. Searching for drug-herb interactions ahead of time would definitely be included in that definition IF one is taking any pharmaceuticals.

But it should be noted that any substance can be misused and abused — even water, even to the point of death. One woman died from consuming too much water in too short a period of time several years ago while participating in a contest sponsored by a radio station

Following are some resources for checking known drug-herb interactions:

A helpful drug-herb interaction chart and article.
National Institutes of Health Library search for herb-drug interactions:
Enter your drug followed by a comma, space and the words “herb-drug interactions” like so:

Cyclosporin, herb-drug interactions

Drug Herb Interactions Chart from the University of Michigan

Another chart of drug-herb interactions

Drug-DRUG interactions

Finally, Consumer Reports’ chart of herb-drug interactions.