Senna is an herbal laxative, approved by the U.S. Food and Drug Administration to relieve constipation. It sometimes appears as an ingredient in popular weight-loss dietary supplements. The result of taking senna is not weight loss. Instead, successful bowel movements are experienced. MedlinePlus states that scientific evidence is not sufficient to support the use of senna for weight loss. If you take senna repeatedly, you may experience diarrhea, electrolyte imbalances and dehydration. Consult a healthcare professional about using senna for weight loss.


Senna comes from the leaves and fruit of a plant that is native to the Middle East and India. Arab texts mention its use as a laxative. Some species also grow in parts of the eastern United States. When taken as a laxative, it stimulates bowel contractions and may cause abdominal cramping and nausea.


In traditional medicine practice, you consume the smallest dose possible to relieve constipation. MedlinePlus states that the common daily dose of senna is 17.2 mg, and you should never take more than 34.4 mg per day. You must also drink eight or more glasses of water while taking senna to relieve constipation. Manufactured laxatives that contain senna have dosage instructions on the product information label. Consumers should not exceed the dosage recommended by the manufacturer.


Senna is available in liquid or capsules and in brand-name laxatives sold in drugstores. The Food and Drug Administration, or FDA, preapproves senna products sold and labeled as laxatives, because it has the authority to regulate the sale of medicinal products. The senna that you purchase as a dietary or weight-loss supplement has not been tested by the FDA, nor can you verify how much senna a dietary supplement or weight-loss tea contains.


Laxative overdose can be severe or fatal. Stimulant laxatives can deplete your body’s potassium. Senna may interact with prescription and over-the-counter medications. It increases the effect of Coumadin and your risk of bleeding. People who take senna and diuretics or water pills may also experience dangerous decreases in potassium blood levels. Pregnant women can use senna for short periods. MedlinePlus notes that senna appears to pass into breast milk but apparently does not affect infants. Laxative dependency and liver damage have resulted from long-term use and higher-than-normal doses of senna. People who experience severe laxative overdose symptoms should call the National Poison Control Hotline.