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Derived from the leaves and fruit of the Senna alexandrina plant, senna tea has been used for centuries as a natural stimulant laxative. Senna is also an FDA-approved nonprescription over-the counter laxative. A stimulant laxative can relieve constipation by stimulating the intestines to undergo a bowel movement. Stimulant laxatives of any kind, senna included, while having important roles in health, can be habit forming and extremely toxic. Severe liver and gastrointestinal damage can occur. Consult a doctor and use with caution.

Liver Toxicity

Several case studies indicate that chronic senna use may cause severe liver damage. Published in the July 2005 issue of "The Annals of Pharmacotherapy," Dr. Bénédicte Vanderperren describes an incident of liver failure as well as some damage to the kidneys in a 52-year-old woman after ingesting a liter of tea containing 70g of senna fruit every day for three years. While the amount of senna this woman took seems exceptionally high, in actuality, according to, chronic abuse of stimulant laxatives with people suffering from eating disorders is a serious problem.

Gastrointestinal Toxicity

The use of senna or any stimulant laxative can cause undue gastrointestinal stress. These adverse reactions, which can range from minor nausea, stomachache and diarrhea, can lead to more severe effects that might include severe cramping, dizziness and bloody stools, to name a few. The Merck Manuals note that abuse of these stimulant laxatives can cause colonic inertia, which occurs when the large intestine stop functioning. Consult your doctor about any potential problems in regards to senna and other laxatives.

Drug Interactions

Senna may potentially interact with certain medications. Senna lowers potassium levels in the body, and this may cause unwanted and potentially dangerous side effects if ingested with diuretics, another medication type that can lower potassium levels. The more serious effects of hypokalemia, or low potassium levels, include muscle weakness, paralysis and heart arrythymias. Senna may also increase the side effects of digoxin, an important heart and reasonably toxic heart medication, according to MedlinePlus.

Herbal Interactions

Senna is thought to potentially interact with certain herbal supplements. MedlinePlus explains that there are certain fears that potassium levels would drop dangerously low in patients who are ingesting senna with horsetail, a self-prescribed supplement that is often used for fluid retention, kidney stones and urinary tract infections. A similar effect is thought to occur if senna is taken along with licorice or other laxative herbals. If taken together with senna, there is a possibility of inducing dangerous hypokalemia. Consult your doctor to ensure your safety.