Also indexed as:Cassia angustifolia, Cassia senna
Senna: Main Image© Steven Foster
Botanical names:
Cassia angustifolia, Cassia senna

How It Works

Senna contains hydroxyanthracene glycosides known as sennosides. These glycosides stimulate colon activity and thus have a laxative effect. Also, these glycosides increase fluid secretion by the colon, with the effect of softening the stool and increasing its bulk.1 Double-blind trials have confirmed the benefit of senna in treating constipation.2, 3 Constipation induced by drugs such as the anti-diarrhea medicine loperamide (Imodium®) has also been shown to be improved by senna in a clinical trial.4

A double-blind trial showed that senna was more effective as a preparatory agent for bowel surgery than the commonly used polyethylene glycol (PEG).5 Patients scheduled to undergo bowel surgery received either 120 mg of senna in a glass of water or 118 mg of PEG in about 2–3 quarts of water the night before surgery. Surgeons rated the efficacy of senna at clearing the bowels at 70%, compared to 58% efficacy for PEG. Supplementation with senna for this purpose should always be supervised by the surgeon.

How to Use It

People using over-the-counter senna products should carefully follow label instructions. An extract in capsules or tablets providing 20–60 mg of sennosides per day is sometimes recommended.6 This can be continued for a maximum of ten days. Use beyond ten days is strongly discouraged. If constipation is not alleviated within ten days, people should seek the help of a healthcare professional.

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The information presented by TraceGains is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. Self-treatment is not recommended for life-threatening conditions that require medical treatment under a doctor's care. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires December 2022.