Senna is an herb commonly used to treat constipation. In fact, senna is approved by the U.S. Food and Drug Administration (FDA) for use as a nonprescription laxative. Commonly found in tea and supplements, this herb is also an ingredient in many detox, or detoxification teas. Since senna stimulates the bowels to empty, teas containing this herb may cause gastrointestinal side effects -- with potentially dangerous side effects if used long-term, in high doses, or by people with certain medical conditions.
Senna tea is made from the leaves of the Cassia senna plant. According to National Institute of Diabetes and Digestive and Kidney Diseases, senna’s active components, known as senna glycosides and sennosides, act as an irritant inside the colon -- enhancing peristalsis or the muscular contractions of the intestines. In addition, these active components keep more fluid in the gut, soften the intestinal contents and stimulate the bowels to empty. When fecal matter moves more quickly through the intestines, symptoms such as gas, bloating, cramping and diarrhea can occur. These are the most common side effects of senna tea -- and most other laxatives.
Drug interaction information on senna laxatives, although not senna tea, is available. Senna can cause dehydration and low electrolyte levels, including life-threatening low potassium levels. Using senna along with diuretics or water pills can make low potassium levels more likely to occur. The stimulant properties of senna tea could also increase the risk of side effects if you use the heart medication digoxin, and consuming this tea along with the blood thinner coumadin could increase the risk of bleeding. Other drug side effects are known, so always discuss planned senna use with your doctor. Senna should also not be taken with other laxatives, as this can increase the risk of gastrointestinal side effects and dehydration.
Due to the senna’s potential to cause gastrointestinal side effects, this herb should not be used if you have disorders of the gut, including ulcerative colitis, Crohn disease or hemorrhoids. Also avoid if you have abdominal pain, ongoing diarrhea or intestinal obstruction. Due to a lack of controlled human studies on senna use during pregnancy, this herb should be used only upon a doctor’s recommendation. Short-term use while breastfeeding is considered acceptable, according to a September 2001 statement published in “American Academy of Pediatrics,” but check with your doctor just to be sure it’s safe for you to use.
Should you use senna tea or supplements for more than 10 to 14 days, your intestines may start to depend on this herb in order to have regular bowel movements. Such long-term use or high doses of senna could also cause an electrolyte imbalance due to low potassium levels, muscle weakness, liver damage or heart problems. While little data is available on safe doses of senna tea, typical recommended doses are no more than 2 cups of brewed tea per day. Also, while the FDA has approved the use of senna as a laxative, this agency does not regulate senna tea -- including its potency, purity and dosing guidelines. Before using senna as a laxative or a detox tea, talk with your doctor to ensure it's safe for you.
- Drugs.com: Senna
- Pediatrics: The Transfer of Drugs and Other Chemicals Into Human Milk
- Natural Medicines Comprehensive Database: Senna
- Liver International: Review of Liver Injury Associated With Dietary Supplements
- U.S. National Library of Medicine: National Institute of Diabetes and Digestive and Kidney Disorders: LiverTox: Senna
Based in Massachusetts, Jessica Bruso has been writing since 2008. She holds a master of science degree in food policy and applied nutrition and a bachelor of arts degree in international relations, both from Tufts University.