Almost everyone will have taken a preparation containing senna at some time in their lives. Senna is probably one of the best known herbal medicines, not least because it is still widely used in conventional medicine. It is a very efficient laxative and is a particularly useful remedy for the occasional bout of constipation. It has a slightly bitter, nauseating taste, and is therefore generally mixed with other herbs.
Habitat & Cultivation
Senna is native to tropical Africa and is now cultivated throughout that continent. It is grown from seed in spring or from cuttings in early summer and requires plenty of sun. The leaves may be picked before or while the plant is in flower, and the pods are collected when they are ripe in autumn.
There are over 400 species of Cassia. Tinnevelly senna (C. angustifolia) is grown in the Indian subcontinent and has the same therapeutic properties as C. senna. In Ayurvedic medicine, it is used for skin problems, jaundice, bronchitis, and anemia, as well as for constipation. Jue ming zi (C. obtusifolia) is used in traditional Chinese medicine for “liver fire” patterns, constipation, and atherosclerosis.
- Anthraquinone glycosides (sennosides)
- Naphthalene glycosides
- Volatile oil
Sennosides: Extensive research during the last 50 years has led to a clear understanding of senna’s action. The sennosides irritate the lining of the large intestine, causing the muscles to contract strongly, resulting in a bowel movement about 10 hours after the dose is taken. The sennosides also stop fluid being absorbed from the large intestine, helping to keep the stool soft.
Traditional & Current Uses
Early records: The herb was first used medicinally by Arabian physicians in the 9th century CE.
Constipation: Senna has always been specifically used for constipation. It is particularly appropriate when a soft stool is required, for example in cases of anal fissure. Senna is a good short-term laxative but should not be taken for more than 10 days as this leads to weakening of the large intestine muscles.
Cathartic: As a cathartic (very strong laxative), senna can cause cramping and colic, and is therefore normally taken with aromatic, carminative herbs that relax the intestinal muscles.