Does Long-Term Use of Rhubarb Increase Cancer Risk?

Concerns have occasionally surfaced about whether long-term use of rhubarb—a traditional herbal remedy derived from the roots and rhizomes of Rheum palmatum, R. officinale, or R. tanguticum—increases cancer risk. Current scientific evidence does not support a causal link between rhubarb consumption and human carcinogenesis.

Rhubarb contains anthraquinone compounds—including emodin, rhein, and aloe-emodin—which exert laxative effects and have been studied for potential antitumor activity in preclinical models. While high-dose, chronic exposure to certain anthraquinone laxatives (e.g., senna, cascara) has raised theoretical concerns due to epithelial irritation and possible DNA interactions, rhubarb itself has not been classified as carcinogenic by major regulatory bodies, including the International Agency for Research on Cancer (IARC), the U.S. National Toxicology Program (NTP), or the European Medicines Agency (EMA).

Clinical data on long-term rhubarb use in humans remain limited. Most safety assessments derive from short-term use (typically ≤1–2 weeks) for constipation relief. Prolonged daily intake may lead to electrolyte imbalances (particularly hypokalemia), melanosis coli (a benign, reversible pigmentation of the colonic mucosa), or cathartic colon—a functional disorder characterized by diminished colonic motility and dependence on laxatives. These adverse effects are pharmacodynamic consequences of chronic anthraquinone exposure, not indicators of malignant transformation.

Importantly, no epidemiological studies have demonstrated an increased incidence of colorectal or other cancers among populations with habitual rhubarb use. In fact, several in vitro and animal studies suggest that emodin and rhein may exhibit antioxidant, anti-inflammatory, and pro-apoptotic properties under controlled conditions—though these findings do not translate to clinical cancer prevention or treatment recommendations.

As with any botanical medicine, rhubarb should be used judiciously: short-term, at recommended doses, and under the guidance of a qualified healthcare provider—especially in individuals with renal impairment, electrolyte disorders, or inflammatory bowel disease. Patients concerned about long-term gastrointestinal health or cancer risk should prioritize evidence-based preventive strategies, including dietary fiber, regular screening, and avoidance of established carcinogens such as tobacco and excessive alcohol.