Is it always safe to use herbal supplements?
Herbal supplements can be purchased over-the-counter (OTC) and may be labeled "all-natural" and are sold in many different forms - dried leaves for teas, powdered, as capsules or tablets, or in solution.
But does "all-natural" mean they are always safe?
Absolutely not! Although herbal supplements may be from plant or herb sources, the active ingredients are potent chemicals. Because of this, herbal supplements can have drug interactions, interactions with other herbs, or with food and alcohol.
Herbal interactions with prescription medications or other chemicals can:
- interfere with how the drug may be broken down in the body
- enhance side effects of prescription medications
- block the intended therapeutic effect of a drug
Alarmingly, feverfew may increase the risk of bleeding, especially in people with blood-clotting disorders or using blood thinners to help prevent clots, for example:
- aspirin
- warfarin
- heparin
- Plavix (clopidogrel)
- Pradaxa (dabigatran)
- Xarelto (rivaroxaban)
- low molecular weight heparins like enoxaparin or dalteparin.
A commonly used flavoring agent, food product, and herbal supplement.
Ginger has been used in the treatment and prevention of motion sickness, vertigo, to increase appetite, to reduce stomach acidity, and to reduce severe nausea and vomiting in pregnancy.
Drug interactions with ginger are not well documented; however, it is known to:
- Inhibit thromboxane synthetase, which can prolong bleeding time and may cause interactions with anticoagulants like warfarin, aspirin, or other blood thinners.
Ginseng has been used in Asian countries for its therapeutic effects for centuries. Today, ginseng use is reported to improve the body's resistance to stress and increase vitality, among other uses.
There are many different origins of ginseng, and many types of drug interactions.
- Long-term use of American ginseng may decrease the effectiveness of warfarin, a blood thinner, and increase the risk for a blood clot. In general, ginseng or ginseng-containing herbal tea should not be used with anticoagulants. Ask your doctor about this interaction.
- Ginseng may also affect blood pressure treatments and diabetic medications like insulin or oral hypoglycemics.
Green tea is a popular drink that originated in China and has been promoted for stomach disorders, to lower cholesterol, as an anti-cancer antioxidant, as a stimulant, and to lessen belly fat, among other uses.
- Dried green tea leaves contain vitamin K, which can increase blood clotting. Large amounts of vitamin K may interfere with the activity of some blood thinners.
A commonly used flavoring agent, food product, and herbal supplement. There are many conditions garlic has been promoted for - to reduce cholesterol and triglycerides, to prevent cancer, to lower blood sugar levels, and to reduce menstrual pain, among other uses. There are over 180 drug interactions with garlic, but most are reported as minor.
- Garlic has been reported to moderately affect blood clotting and blood sugar levels and may affect people who take blood-thinning agents like aspirin, warfarin, or clopidogrel (Plavix).
- Use of garlic supplements with HIV protease inhibitors (PI) may decrease the PI blood levels.
- There are other possible garlic interactions, so be sure to review all possible drug interactions with garlic and speak with your healthcare provider.
A flowering herb that grows in the northeast United States. Common uses for goldenseal include skin infections, cold and flu symptoms, and to treat diarrhea, but the evidence is weak for these uses.
- Serious interactions may occur with certain antipsychotic drugs - using pimozide or thioridazine with goldenseal is not recommended, as antipsychotic blood levels may rise leading to an irregular heart rhythm.
- Goldenseal may affect liver enzymes that can alter blood levels of certain drugs; always have your pharmacist run a drug interaction screen on all of your medicines, OTC drugs, or herbs.
The use of ginkgo extract dates back centuries in traditional Chinese medicine.
Ginkgo interacts with over 260 drugs; have a pharmacist check for interactions before use.
Ginkgo has been used for treating anxiety, dementia, circulation problems in the legs, premenstrual syndrome, certain vision problems, dizziness), or some movement disorders. Research has shown that Ginkgo Biloba is not likely to be effective in treating heart disease.
- Ginkgo may decrease the antiviral effects of drugs used in HIV, such as efavirenz.
- Avoid ginkgo in patients who take seizure medications and blood thinners.