Senna adverse effects

Castor oil is broken down in the small intestine to ricinoleic acid, which is very irritating to the gut and promptly increases peristalsis. Cascara, senna, and aloe contain emodin which stimulates colonic activity. Onset of activity is delayed 6 to 8 hr because emodin is excreted into the colon after these agents are absorbed. Emodin may pass into breast milk. Phenolphthalein and bisacodyl are also potent stimulants of the colon. Adverse effects include abdominal cramps and the potential for atonic colon with prolonged use. 

From the description of the adverse effects, a stimulating laxative seems most likely, as they commonly cause abdominal cramps. Senna is a stimulant laxative and is available as brown tablets, and so this seems the most likely laxative. 

Discuss the adverse effects his wife has experienced and explain that senna is in fact a herbal medicine and that herbal remedies may not necessarily be gentle. 

Discuss the benefits of senna (as above). He could try starting with one tablet to minimise the adverse effects. If he accepts this suggestion counsel him to take the tablets before bed (as they take 8-10 hours to work). If he is reluctant to try senna explain to him that lactulose is often insufficient alone in treating opioid-induced constipation, and may take 48 hours to work. 

The safety and efficacy of senna have been reviewed (4). Its rhein-anthrone-induced laxative effects occur through two distinct mechanisms, an increase in intestinal fluid transport, which causes accumulation of fluid intralumm-ally, and an increase in intestinal motihty. Senna can cause mild abdominal complaints, such as cramps or pain. Other adverse effects are discoloration of the urine and hemorrhoidal congestion. Prolonged use and overdose can result in diarrhea, extreme loss of electrolytes, especially potassium, damage to the surface epithelium, and impairment of bowel function by damage to autonomic nerves. Abuse of senna has also been associated with melanosis coli, but resolution occurs 8-11 months after withdrawal. Tolerance and genotoxicity do not seem to be problems associated with senna, especially when used periodically in therapeutic doses. 

The FDA has received reports of four deaths as well as other adverse effects associated with the use of herbal laxative "dieters" teas (Kurtzweil, 1997). These teas contain laxatives such as senna, aloe, and buckthorn. Shortterm reactions are nausea, vomiting, cramping, and diarrhea, which may last several days and usually occur in those who exceed the recommended dose. 0[ther adverse effects include chronic diarrhea, dependence on laxatives for normal bowel function, and abdominal pain, which occur with long-term use. Severe reactions such as fainting, dehydration, and electrolyte disorders may occur in those with underlying nutritional disorders such as an eating disorder or excessive dieting. 

Other than abdominal cramps, which occur in approx 10% of patients, it does not appear that senna causes any serious adverse gastrointestinal effects (Muller-Lissner, 1993). Products containing crystalline glycosides of senna are more stable, more reliable, and cause less cramping than products made from the crude drug (Curry, 1986). 

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