Cascara sagrada, a member of the buckthorn family, grows in the Pacific Northwest from northern California to British Columbia. The dried and aged bark was a common treatment for constipation in Native American medical tradition. The Food and Drug Administration banned the use of cascara in over-the-counter and prescription laxatives in 2002. The ban, however, does not apply to herbal remedies and dietary supplements, nor to laxatives with cascara sagrada that were already on the market. Some diet supplements and herbal colon cleansers include cascara sagrada as a purgative, but users should be aware of its possible side effects and dangers.
Cascara sagrada is a stimulant laxative that works by irritating your colon muscles and making them contract. Using cascara regularly for a long period of time can permanently damage your digestive tract and make you dependent on laxatives for bowel movements, according to James Duke, author of "The Green Pharmacy Herbal Handbook," and numerous others. In fact, the FDA has long required that preparations containing cascara carry a warning against using them for more than one week unless directed by a doctor.
Overuse of cascara sagrada may lead to electrolyte imbalance. Your bodily fluids normally contain minerals and salts like potassium, sodium and calcium in precise proportions. When something upsets the balance of those minerals, called electrolytes, your body cannot function properly. Diarrhea, one of the possible side effects of cascara sagrada, is one common cause of electrolyte imbalance. Electrolyte imbalance can result in symptoms that range from dizziness and blurred vision to organ failure and death, according to "Go Ask Alice," a service provided by Columbia University Health Services.
Harsh laxatives like cascara sagrada can cause diarrhea, which may result in dehydration. Higher doses of cascara are more likely to cause diarrhea to the point of dehydration, which can result in weakness, blurred vision, confusion, fainting, kidney damage and death.
Fresh Bark Dangers
Herbal supplements should contain cascara sagrada bark that has been aged for at least one year. Fresh bark has higher levels of the active ingredients in cascara, which can cause severe diarrhea, bloody diarrhea, vomiting and abdominal cramps.
You should talk with your physician or health care provider before taking products containing cascara sagrada if you are taking heart stimulant medications such as digitalis, or diuretics. According to Duke, cascara sagrada may increase the potency of those drugs and possibly lead to potassium deficiency.
Dangers with Other Conditions
You should not use products containing cascara sagrada if you have abdominal pain, nausea or are vomiting, or if you have any chronic intestinal disorder, including Crohn's disease, irritable bowel syndrome and ulcerative colitis, according to the University of Utah Health Center website.
The University of Utah Health Center also reports that emodin, a substance in cascara bark, is under evaluation as a possible carcinogen. The evidence suggests that cascara sagrada is probably not carcinogenic if used in recommended dosages, according to "Botanical Dietary Supplements Gone Bad," an article published in Chemical Research in Toxicology The authors caution, however, that chronic use could lead to "gentoxic events"--damage to cell DNA that could cause mutations common in cancer.