Cascara - Rhamnus purshiana (in the Rhamnaceae or Buckthorn family)
Part used: Bark that has been aged a minimum of one year.
Tendencies: Cooling and drying.
Dosage: Decoction: 1 heaping teaspoon per cup of water; or 1:5 dry liquid extract: 20 - 70 drops 1-4 times per day in a little water.
Use: (a) Laxative, (b) Cholagogue.
Most uses are due to cascara's laxative effect. It acts on the large intestine to stimulate peristalsis and increase secretion of water into the large intestine lumen. It is used for constipation, anal fissures, hemorrhoids, after rectal operations and is specific for chronic constipation with hepatic sluggishness.
The bark contains the anthraquinone glycosides rhamnoemodine, rhamnicoside and shesterine and are activated by intestinal flora. Emodin, has been shown to possess anticancer, antibacterial, diuretic, immunosuppressive, and vasorelaxant activities in research with animals.
Contraindications: Do not use for extended periods of time. Chronic use will deplete electrolytes, especially potassium, bringing about muscle weakness and paralysis of intestinal musculature, making the laxative less effective, promoting constipation and thus requiring more of the laxative to be used.
Potassium loss can disturb cardiac rhythm and potentiate cardiac glycoside toxicity. Herbs with cardiac glycosides include pheasant's eye (Adonis) lily of the valley (Convallaria), fox glove (Digitalis), false hellebore (Helleborus), Strophanthus and Urginea. Physicians should closely monitor individuals who consume formulas with anthraquinones while taking cardiac glycosides.
An overdose or overusage of anthraquinones may cause vomiting, intestinal spasms and bloody diarrhea. An overdose may cause kidney inflammation. Cascara, as with all laxatives, should not be used in cases of intestinal obstruction when there is danger of an intestinal rupture. Any herb containing anthraquinone should not be consumed by pregnant women or nursing mothers because it can be passed through breast milk to the baby. It is also contraindicated in abdominal pain of unknown origin and children under the age of 12 due to loss of water and electrolytes. Emodin has also been reported to be a mutagen in a few experiments.