The Health Benefits of Senna

This common laxative has been used to treat constipation for centuries

Maša Sinreih in Valentina Vivod/Wikimedia Commons/CC BY-SA 3.0

The herb senna has been used for thousands of years to combat constipation. It is FDA-approved as an over-the-counter stimulant laxative for the treatment of constipation or as a bowel cleanse prior to surgery or diagnostic testing of the digestive tract.

Senna's active agent is sennosides, a plant compound in the anthraquinone family. Sennosides work by irritating the lining of the bowel, creating a powerful laxative effect.

When taken by mouth, senna typically produces a bowel movement in 6 to 12 hours, but it can be effective in as little as 10 minutes when taken rectally.

Other Names For Senna

  • Sennoside
  • Senna glycoside
  • Cassia senna

Health Benefits

Senna is safe and effective for treating constipation in adults and children. The herb is also purported to treat anal fissures and hemorrhoids, and to promote weight loss, however, there is limited research to support these claims.

The natural laxative is often prescribed for pediatric patients. A 2018 literature review and analysis published in the Journal of Pediatric Surgery found that long-term use of senna appears to be safe for children with chronic constipation, although side effects such as a blistering diaper rash may appear with prolonged skin contact to feces produced from senna.

Possible Side Effects

Side effects of senna may include abdominal cramps and pain from muscle contractions, dark or discolored urine, electrolyte imbalance, nausea, rash, and swelling of the fingertips. Prolonged use of senna may lead to dark pigmentation in the colon, called melanosis coli.

Discontinue use and call your doctor if you experience bloody diarrhea or prolonged abdominal pain after senna use. In large doses and prolonged use, senna has been linked to liver toxicity.

In children who are not toilet trained, senna use is linked to diaper rash with blisters that may be severe. Doctors recommend changing your child's diaper immediately after stooling while taking senna and cleaning the diaper area thoroughly. If your child develops a diaper rash with blisters or cracked skin, call your pediatrician.

Senna should not be used for more than seven consecutive days unless under a doctor's supervision.

Senna or other anthraquinone-containing herbs should not be used by people with diverticular disease, ulcerative colitis, Crohn's disease, severe hemorrhoids, blood vessel disease, congestive heart failure, heart disease, severe anemia, abdominal hernia, gastrointestinal cancer, recent colon surgery, or liver and kidney disease. 

Senna may interact with drugs called calcium channel blockers and the drug Indocin.

Dosage and Preparation

Senna comes in tablets and liquid formulations, and is also available as a tea. Dosing varies based on patient age and uses. Talk to your doctor to find the right dose for you, but here are some general guidelines:

  • Adults for constipation: The typical dose is 17.2 mg daily, not to exceed 34.4 mg twice a day.
  • Post-pregnancy constipation: The usual recommended dose is 28 mg daily, taken in two 14 mg doses.
  • Elderly patients for constipation: The typical daily dose is 17.2 mg.
  • Adults for bowel preparation: Doses of senna containing 75 mg of sennosides taken the day before colonoscopy, with up to 150 mg taken once or twice the day before colonoscopy.
  • Children ages 12 and over for constipation: The usual dose is 2 tablets, with 8.6 mg sennosides per tablet, once daily. The maximum dose is 4 tablets (34.4 mg sennosides) twice daily.
  • Children ages 6 to 11 years old for constipation: The usual dose is 1 tablet (8.6 mg sennosides) daily. The maximum dose is 2 tablets (17.2 mg sennosides) twice daily.
  • Children ages 2 to 5 years: The usual dose is 1/2 tablet (4.3 mg sennosides) daily. The maximum dose is 1 tablet (8.6 mg sennosides) twice daily.

What to Look For

As a medicine, senna is derived from the leaves and fruit of the senna plant. Senna made from the fruit is more gentle than preparations made from the leaf.

The American Herbal Products Association (AHPA) recommends that senna leaf products be labeled, "Do not use this product if you have abdominal pain or diarrhea. Consult a healthcare provider prior to use if you are pregnant or nursing. Discontinue use in the event of diarrhea or watery stools. Do not exceed recommended dose. Not for long-term use."

There are no warnings about preparations made from senna leaf and it is considered safe for long-term use.

Other Questions

How long does senna take to work?

The sennosides in this herb typically produce a bowel movement in 6 to 12 hours when taken orally. For faster results, senna can be taken rectally and may take effect in as little as 10 minutes.

Is senna safe to take every day?

While the herb is generally regarded as safe and may be prescribed for everyday use, it is recommended to not take senna for more than seven consecutive days, unless under a doctor's supervision.

Will senna give me a stomach ache?

Senna works to treat constipation by irritating the lining of the intestines, which stimulates the digestive tract to move stool through it. Some people report abdominal cramps after taking senna, which resolves once a bowel movement is complete.

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