Ephedra is the plant from which ephedrine was originally isolated. Until 2004, ephedra—also called ma huang—was used in many herbal products, including supplements promoted for weight loss. To prevent potentially serious interactions, people taking ephedrine or pseudoephedrine should avoid using ephedra-containing drug products and should read product labels carefully for ma huang or ephedra content. Native North American ephedra, sometimes called Mormon tea, contains no ephedrine.

Caffeine, which is found in coffee, tea, chocolate, guaraná (Paullinia cupana), and some nonprescription and supplement products, can amplify the side effects of ephedrine and pseudoephedrine. People should avoid combination products containing ephedrine/pseudoephedrine/ephedra and caffeine.

Tannins are a group of unrelated chemicals that give plants an astringent taste. Herbs containing high amounts of tannins may interfere with the absorption of ephedrine or pseudoephedrine taken by mouth. Herbs containing high levels of tannins include green tea, black tea, uva ursi (Arctostaphylos uva-ursi), black walnut (Juglans nigra),red raspberry (Rubus idaeus),oak (Quercus spp.), and witch hazel (Hamamelis virginiana).