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Photo copyright Steven Foster

Senna

Botanical names: Cassia senna, Cassia angustifolia

Parts used and where grown: The senna shrub grows in India, Pakistan, and China. The leaves and pods are used medicinally.



Senna has been used in connection with the following conditions (refer to the individual health concern for complete information):

Rating Health Concerns
3Stars Constipation
2Stars Bowel Surgery (preparation for)
3Stars Reliable and relatively consistent scientific data showing a substantial health benefit.
2Stars Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit.
1Star An herb is primarily supported by traditional use, or the herb or supplement has little scientific support and/or minimal health benefit.

Historical or traditional use (may or may not be supported by scientific studies): People in northern Africa and southwestern Asia have used senna as a laxative for centuries. It was considered a “cleansing” herb because of its cathartic effect. In addition, the leaves were sometimes made into a paste and applied to various skin diseases. Ringworm and acne were both treated in this way.

Active constituents: 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 much is usually taken? 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.

Are there any side effects or interactions? Some people may develop a dependency on senna for normal bowel movements. Therefore, senna must not be used for more than ten consecutive days. Chronic senna use can also cause loss of fluids, low potassium levels and diarrhea, all of which can lead to dehydration and potentially negative effects on the heart and muscles. The safety of senna during pregnancy and breast-feeding is controversial. Most guidelines suggest avoiding senna during the first trimester of pregnancy.7 8 It is best to consult a physician. Senna is not recommended for children under the age of ten years. People with Crohn’s disease, ulcerative colitis, appendicitis, intestinal obstructions, and abdominal pain should not supplement with senna.9

Are there any drug interactions? Certain medications may interact with senna. Refer to the drug interactions safety check for a list of those medications.

References:

1. Leng-Peschlow E. Dual effect of orally administered sennosides on large intestinal transit and fluid absorption in the rat. J Pharm Pharmacol 1986;38:606–10.

2. Passmore AP, Davies KW, Flanagan PG, et al. A comparison of Agiolax and Lactulose in elderly patients with chronic constipation. Pharmacol 1993;47(suppl 1):249–52.

3. Kinnunen O, Winblad I, Koistinen P, Salokannel J. Safety and efficacy of a bulk laxative containing senna versus lactulose in the treatment of chronic constipation in geriatric patients. Pharmacol 1993;47(suppl 1):253–5.

4. Ewe K, Ueberschaer B, Press AG. Influence of senna, fibre, and fibre+senna on colonic transit in loperamide-induced constipation. Pharmacol 1993;47(suppl 1):242–8.

5. Valverde A, Hay JM, Fingerhut A, et al. Senna vs polyethylene glycol for mechanical preparation the evening before elective colonic or rectal resection: a multicenter controlled trial. French Association for Surgical Research. Arch Surg 1999;134:514–9.

6. Gruenwald J, Brendler T, Jaenicke C. PDR for Herbal Medicines. Montvale, NJ: Medical Economics, 1998, 722–4.

7. Mengs U. Reproductive toxicological investigations with sennosides. Arzneimittelforschung 1986;36:1355–8.

8. Faber P, Strenge-Hesse A. Relevance of rhein excretion into breast milk. Pharmacol 1988;36(suppl 1):212–20.

9. Blumenthal M, Busse WR, Goldberg A, et al. (eds). The Complete Commission E Monographs: Therapeutic Guide to Herbal Medicines. Boston, MA: Integrative Medicine Communications, 1998, 204–8.