How Herbal Supplements Interact with Drugs

Herbal medicines have been used by people since ancient times in various civilizations. But lately, the issue of herb-drug interactions has ominously appeared over the practice of herbal medicine. It has been noted that herb-drug interactions may not necessarily be a chemical interaction between a drug and a component of the herb that produces something toxic. The interaction may cause a herb component to either increase or decrease the amount of a drug in the blood stream. The herb may also lead to reducing the effect of the drug or increasing the drug effect.

Even though herbal supplements are popular these days, most people still take over the counter drugs and those prescribed by a doctor, in which case not telling the doctor about the herbal supplements, may lead to dangerous consequences. Mixing herbs with medicines should be done wisely. It has been discovered that grapefruit juice could affect drug metabolism. The biggest concern about drugs and their interactions with herbs are those medicines that people took continuously – such as blood thinners that are prescribed after a heart attack or stroke. Antidepressants are another concern.

Some of the commonly used herbs and their interactions with drugs are given below:

Feverfew (used for migraines and arthritis), garlic (to reduce blood cholesterol, triglycerides and blood pressure), ginger (nausea, vomiting and vertigo) and Ginko biloba (for increased blood circulation and improving memory and mental alertness) are said to have a blood thinning effect, and may increase bleeding especially in patients taking anti-clotting medications.

Echinacea, which is said to boost the immune system and help fight colds and flu may cause inflammation of the liver if used with certain medications such as anabolic steroids. Licorice, which is used for treating stomach ulcers may cause high blood pressure, swelling or electrolyte imbalances.

Persons using Ginseng (used to increase physical stamina and mental concentration), sometimes see increased heart rate or high blood pressure. Goldenseal may worsen swelling and high blood pressure. Saint John’s-wort should not be taken when taking antidepressant medication and the herb may intensify the effects of sedatives and diabetes medication.

Having said this, it would be prudent to note that in the article, ‘CHECKING FOR POSSIBLE HERB-DRUG INTERACTIONS’ by Subhuti Dharmananda, Ph.D., Director, Institute for Traditional Medicine, Portland, Oregon, it is mentioned that, “A standard procedure is to test the herb extract alone and to also test it with drugs that cause the same effect. If the drug effect is increased or prolonged by the herb, it is implied that the herb has a similar effect, even though it may have a different mechanism. Thus, a study intended to demonstrate that a traditional claim for an herb is true turns out to be a source of worry about herb-drug interactions. However, the amount of herb used in the pharmacology experiments of this type is often far higher than the amount normally used in clinical practice; the likelihood of herb-drug interactions occurring with normal use of the herb may be minimal.”

“When published reports alluding to adverse herb reactions (but not interactions) and to pharmacology studies only are eliminated, one is left with few instances of reported herb-drug interactions. This is likely due to the low dose of any individual herb component usually consumed and the simple absence of significant interaction at any reasonable dose.”

The best thing to do would be to consult with your doctor before taking herbal supplements.