Senna is a natural medicine containing sennosides that are derived from the leaves of the Senna plant. Sennosides irritate the lining of the bowel causing a laxative effect.
Senna has been used in alternative medicine as a laxative and an aid to treat constipation.
Not all uses for senna have been approved by the FDA. It should not be used in place of medication prescribed for you by your doctor.

Senna is often sold as an herbal supplement. There are no regulated manufacturing standards in place for many herbal compounds and some marketed supplements have been found to be contaminated with toxic metals or other drugs. Herbal/health supplements should be purchased from a reliable source to minimize the risk of contamination.

• Constipation. Taking senna by mouth is effective for short-term treatment of constipation. Senna is an FDA-approved nonprescription drug for adults and children ages 2 years and older. However, in children ages 3-15 years, mineral oil and a medication called lactulose might be more effective than taking senna. 
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• Senna also appears to be effective for treating constipation when used in combination with psyllium or docusate sodium. In elderly people, senna plus psyllium is more effective than lactulose for treating ongoing constipation. Senna plus docusate sodium is effective for treating constipation in the elderly and in people who have undergone anorectal surgery. Taking senna appears to be as effective as lactulose, psyllium, and docusate for relieving constipation in people taking opioids or loperamide.

• Bowel preparation before colonoscopy. Taking senna by mouth is as effective as castor oil and bisocodyl for bowel preparation. Some evidence suggests that senna is also at least as effective as polyethylene glycol for bowel preparation. However, conflicting evidence exists. It is unclear if taking senna with polyethylene glycol is more effective than taking polyethylene glycol alone. Senna appears to be less effective than sodium phosphate for bowel cleansing. However, taking a combination of senna, sodium picosulfate, and polyethylene glycol appears to be more effective than sodium phosphate for bowel preparation prior to colonoscopy.

Ask a doctor, pharmacist, herbalist, or other healthcare provider if it is safe for you to use senna if you have:
It is not known whether senna will harm an unborn baby. Do not use this product without medical advice if you are pregnant.

It is not known whether senna passes into breast milk or if it could harm a nursing baby. Do not use this product without medical advice if you are breast-feeding a baby.
Some forms of senna are made for use by children. Do not give any herbal/health supplement to a child without the advice of a doctor.

Senna side effects

Get emergency medical help if you have any of these signs of an allergic reaction to senna: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.
Call your healthcare provider at once if you have a serious side effect such as:

• Digoxin (Lanoxin) interacts with SENNA

• Warfarin (Coumadin) interacts with SENNA

• Water pills (Diuretic drugs) interacts with SENNA