Table 6.

Drug-Herbal Interactions

HERBCONVENTIONAL DRUGPOSSIBLE MECHANISM
AnthraquinonesMay potentiate digitalis and other cardiac glycosides, corticosteroids, thiazude diuretics due to increased potassium loss• Large amounts and long-term use of anthraquinones can lead to electrolyte (eg, potassium) loss.
Aloe vera leaf lining• May reduce absorption of drugs due to decreased bowel transit time.
Buckthorn berries and bark (Rhamnus catharticus)
Cascara sagrada bark (Rhamnus purshiana)
Senna leaf and fruit (Cassia sp)
Feverfew (Tanacetum parthenium)May potentiate anticoagulants and aspirin• May impede platelet aggregation and prostaglandin synthesis
Garlic (Allium sativum)May potentiate anticoagulants and antiplatelet drugs• Decreases platelet aggregation and increases fibrinolytic properties.
Ginkgo (Ginkgo biloba)May potentiate aspirin, nonsteroidal anti-inflammatory drugs, warfarin, heparin, and other anticoagulant and antiplatelet drugs• Inhibits platelet activating factors.
• Case reports of spontaneous bleeding, including a spontaneous hyphemia from a patient on aspirin.
Ginseng (Panax ginseng)May interact with phenelzine and anticoagulants• Panax ginseng has antiplatelet components. Panaxynol, an antiplatelet constituent in ginseng, inhibits thromboxane formation.
• One case reports probable interaction between ginseng and warfarin.
• Case reports of headache and manic episodes with concurrent use of phenelzine.
Hawthorn (Crataegus species)May potentiate digitalis and cardiac glycosides• Polymeric procyanidins in Hawthorn may increase activity of digitalis and reduce toxicity of cardiac glycosides due to coronary vasodilation and antiarrhythmic effects.
Kava-Kava (Piper methysticum)May potentiate benzodiazepines, alcohol, and central nervous system depressants• May show synergism with GABA receptors
• Case report notes possible interaction with alprazolam.
Licorice (Glycyrrhiza glabra)May potentiate digitalis and cardiac glycosides due to increased potassium loss and corticosteroids; may increase potassium loss with thiazide diuretics; spironolactone antihypertensive effects diminish• Decreases activity of 11 beta-hydroxysteroid dehydrogenase, leading to an aldosteronism effect of potassium loss and sodium retention.
Ma huang (Ephedra sinica)May induce toxicity from monoamine oxidase inhibitor antidepressants and potentiate methylxanthines, caffeine, theophylline, cardiac glycosides, and anesthetics• Indirectly stimulates sympathomimetic and central nervous system.
Valerian (Valerian officinalis)May potentiate sedatives and barbiturates• May bind to GABA receptors.