Cascara – are we barking up the wrong tree?

The Irish Times
Health Supplement, p. 13
31 March 2009

DOES IT WORK? Cascara and constipation

CASCARA is the dried bark of a tree native to the Pacific coast of North America. Native Americans used it as a natural laxative for treating constipation.

When Spanish explorers learned of the remedy, they named it cascara sagrada, which literally means “sacred bark”.

Fresh bark contains a substance called anthrone which causes severe vomiting. The bark must be aged for one year to allow time for the anthrone to decompose. The best products use bark that has aged for three years which is reported to have a milder laxative effect, yet still be effective.

Constipation is an occasional annoyance for most people, but can become more prevalent in older people. Surveys have found that among those over 65 years, one-quarter of men and one-third of women can develop chronic constipation.

Serious complications can develop, which leads many to use laxatives regularly.

While a number of pharmaceutical products are available, some prefer to use herbal products.

Cascara is available as capsules, liquid extracts and dried bark to make a tea. The tea can be very bitter, so the capsules tend to be the most popular.

Evidence from studies 

Cascara bark has been extracted and found to contain a group of compounds called anthraquinolones. These have been isolated from a number of herbs and are known to have laxative effects.

The type of anthraquinolone found in cascara is not active until after it passes through the stomach. Bacteria in the intestine break the molecules down into the active laxative.

This then directly stimulates the intestine to contract and eliminate its contents. The active ingredients thus act directly where they are needed, minimising side effects.

However, this also delays the response to the remedy for a few hours.

It is very important that additional doses are not taken during this time.

Although cascara has been used for many years, only a small number of studies have been conducted on it. These do show that cascara is effective and safe as a mild laxative. The usual recommended dose is whatever provides about 20 to 30mg of anthraquinolones.

This is usually taken at bedtime to allow time for active form of the drug to be released in the intestines. Practically, the smallest dose that restores regular movements should be used.

Problematic aspects 

Cascara itself is relatively safe, although it can cause stomach discomfort and cramps.

Laxatives in general should not be used for more than a week. Extended use of laxatives can lead to dehydration and electrolyte imbalances.

Chronic constipation can be a symptom of more serious problems and should be discussed with a healthcare professional. Anyone with an intestinal obstruction, ulcers or abdominal pain of unknown origin should talk to a GP before using cascara. Women who are pregnant or breastfeeding should not use cascara as its effects on the unborn or babies have not been studied.


Cascara has a long-standing reputation as a safe and effective laxative. It can be recommended for short-term use to relieve constipation, but long-term use (more than a week) of any laxative is not recommended.

A study conducted in a retirement nursing home in New York noted that almost half the residents were taking laxatives, including cascara. The daily fibre intake was found to be less than half the recommended allowance (about 25-30g per day). After the fibre intake was increased to within the recommended levels with a powdered natural fibre, two-thirds of the residents were able to stop taking laxatives and saved money doing so.

While cascara may be helpful in the short term, many cases of constipation respond better to increased intake of fluids, fruits, vegetables and dietary fibre.

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