Cascara Bark (Rhamnus purshiana): The Sacred Bark Laxative
By Anjela Jeganathan – Holistic Medical Herbalist | Herba Naturalle
Cascara — Rhamnus purshiana (also Frangula purshiana) — known as Cascara Sagrada (“Sacred Bark”) from the Spanish of the Pacific Northwest explorers who learned of it from Native American peoples, is one of the most widely used and well-documented herbal laxatives in the world. It was included in the United States Pharmacopeia from 1890 to 1975 and was an over-the-counter pharmaceutical laxative in the US for decades. Its anthraquinone-based mechanism is well understood, and it remains one of the most reliable stimulant laxatives available from the plant kingdom.
At Herba Naturalle, Cascara Bark is listed in the comprehensive herb index as a stimulant laxative herb. The Digestive Reset Bundle provides a more comprehensive, root-cause approach to bowel health.
Active Compounds
- Anthraquinone glycosides (cascarosides A–D) — the primary active compounds; converted by intestinal bacteria to active anthrones that stimulate peristalsis and increase water and electrolyte secretion into the bowel
- Aloin, barbaloin, and emodin — related anthraquinone compounds
- Tannins — mild astringent contribution
The aged and dried bark must be used — fresh bark contains bianthrones that cause severe vomiting and cramping. Cascara must be aged at least one year to allow these compounds to oxidise to the safer anthraquinone glycosides.
Clinical Applications
Constipation
The primary and well-evidenced application. Cascara produces a bowel movement 6–12 hours after ingestion by stimulating colonic peristalsis. It is used for occasional and short-term constipation. It is gentler in action than Senna and produces less griping, making it better tolerated for most patients.
Bowel Preparation
Historically used for bowel preparation before examination and surgery.
Important Context
Cascara addresses the symptom of constipation but not its cause. For long-term bowel health, the Digestive Reset Bundle and Berberis Plus from Herba Naturalle address the root physiological patterns — sluggish bowel muscle, poor digestive secretions, and gut lining dysfunction — that produce chronic constipation.
⚠ Safety — Important
- Short-term use only: Maximum 1–2 weeks without professional guidance; prolonged use causes laxative dependence and electrolyte imbalance
- Pregnancy and breastfeeding: Contraindicated
- Children under 12: Not recommended
- IBD, intestinal obstruction: Contraindicated
- Urine may turn reddish-brown — harmless
- Only use aged, dried bark preparations from reputable suppliers
Browse the Herba Naturalle herb index, explore the clinical herbal philosophy, and contact the clinic. The full product range is available online.
This article is for informational purposes only. Please consult a qualified medical herbalist before use.