Table 1.
Some clinically significant drug-herb interactions:
| Herbal drugs | Biological source | Interaction reported or suspected |
| Ginkgo | Ginkgo biloba | Concurrent use of ginkgo and nonsteroidal antiinflammatory agents may result in an increased risk of bleeding and with warfarin causes bleeding. (Meisel et al., 2003) |
| Garlic | Allium sativum | Concurrent use of garlic and anticoagulants result in increased risk of bleeding. (Legnani et al., 1993) |
| Ginger | Zingibar officinale | Concurrent use of ginger and anticoagulants may result in increased risk of bleeding, sulfa guanidine enhance absorption. (Kruth et al., 2004) |
| Ginseng | Panax ginseng | Concurrent use of ginseng and antidiabetic agents may result in increased risk of hypoglycemia. (Vuksan et al., 2000) |
| St. John's wort | Hypericum perforatum | Concurrent use of digoxin and St John's wort may result in reduced digoxin efficacy. (Hennessy et al., 2003) |
| St. John's wort | Hypericum perforatum | Warfarin (cause bleeding); serotonin-uptake inhibitors (cause mild serotonin syndrome); indinavir (decreased bioavailability); digitoxin, theophylline, cyclosporin, phenprocoumon and oral contraceptives reduces bioavailability. (Cupp et al., 1999) |
| Rhubarb | Rheum officinale | Cardiac glycosides and anti-arrhythmic agents potentiates by reducing potassium via laxative effect. (Westendorf, 1993) |
| Astragalus | Astragalus membranaceus | Cyclosporine, azathioprine, methotrexate impair immunosuppressive effects. |
| Licorice | Glycyrrhiza uralensis | Corticosteroids and thiazide diuretics potentiating; digitalis or other cardiac glycosides increases sensitivity (Mu et al.,2006) |
| Ma-huang | Ephedra sinica | With MAO inhibitors cause hypertension; cardiac glycosides or halothane react to produce cardiac arrhythmia; caffeine intensify cardiovascular side effects. |
| Aloe | Aloe ferox | Cardiac glycosides and antiarrhythmic agents potentiates by reducing potassium via laxative effect (Westendorf, 1993) |
| Salvia | Salvia miltiorrhiza | With warfarin cause bleeding (Gaddis et al., 2002) |
| Bupleurum | Bupleurum falcatum | With sedatives potentiating effect |