Senna is the dried leaf or pod of Alexandria senna and Tinnevelley senna. Both species have recently been referred to by botanists as Senna alexandrina. They are members of the pea family native to Eurasia, now cultivated commercially in the Middle East and India. Tinnevelley senna is most widely used in the United States.
Powdered leaf tea has been used for many centuries, both in Eastern and Western traditions, for its laxative qualities.
Senna does one thing, and does it well-relieve constipation. Its leaves and pods contain anthranoids which have specific effects in the intestines: chemical by-products of senna metabolism stimulate propulsive contractions and inhibit stationary contractions in the colon, thus speeding elimination of waste and increasing its water and electrolyte content.
Senna leaves contain about half as much of the active compounds as the pods, but they are considered safer to use. Senna is less expensive than cascara sagrada, but it is a stronger laxative with a greater tendency to cause cramping. The leaves, as well as the anthranoids extracted from them, are still official drugs in U.S. Pharmacopoeia.
Senna is available in a number of product forms including the dried leaf and pods. Because it is a strong laxative, it is best to use commercially prepared non-prescription drug preparations which have more predictable effects.
Senna should not be used for more than a week without a physician's advice. Longer use can cause dependency on laxatives as the bowels may become chronically sluggish. Proper diet and exercise will do much to avoid the need for laxatives. Some individuals may experience discomfort or cramping after using senna products. Prolonged use can lead to fluid and electrolyte imbalances, such as potassium loss, which can reduce the effectiveness of prescribed heart medications. Avoid using senna with licorice root, thiazide diuretics, or steroids because of the potential for potassium loss. Senna should not be used by pregnant or nursing women.