Common Names
- Turkish rhubarb
- Chinese rhubarb
- Tai huang
- Da huang
For Patients & Caregivers
How It Works
Rhubarb acts as a stimulant laxative, but has not been shown to treat or prevent cancer.
Rhubarb is a perennial herb, the stalks of which are consumed as food. The rhizome and roots are used as laxatives and to treat ulcers, constipation, diarrhea, hypertension, immunosuppression, and cancer in Traditional Chinese medicine. Compounds in rhubarb called anthraquinones cause tumor death in mice implanted with some solid tumors, and reduce pain and inflammation in laboratory animals.
Clinical studies showed that rhubarb helps improve feeding tolerance and relieving gastrointestinal dysfunction in critically ill patients; in preventing the incidence of post endoscopic retrograde cholangiopancreatography pancreatitis (PEP) and hyperamylasemia in high-risk patients; for treating recurrent aphthous stomatitis (RAS); and may benefit patients with acute organophosphorus pesticide poisoning (AOPP).
Rhubarb is considered to be a stimulant laxative. It is also a component of Essiac tea. Patients and physicians should be aware of the potential for additive effects.
Purported Uses
-
To reduce the severity of side effects from anticancer therapy
One study suggested that a rhubarb extract may reduce side effects associated with radiation therapy in lung cancer patients. -
To relieve constipation
Rhubarb acts as a laxative, although clinical trials have not tested this use. -
As a fever reducer
There is no scientific evidence to support this claim. -
To suppress the immune system
Laboratory data shows that rhubarb decreases the activity of isolated immune cells. -
To reduce inflammation
Some studies suggest that rhubarb has anti-inflammatory effects. -
To treat infections
There is not scientific evidence to support this claim. -
To treat ulcers
Rhubarb was shown to be useful for treating oral ulcers. More studies are needed.
Do Not Take If
- You are taking Digoxin: Potassium loss due to the laxative effect of rhubarb can increase hypokalemia.
- You are taking Cytochrome P450 substrate drugs: Rhubarb may reduce the effectiveness of these drugs. But clinical significance has yet to be determined.
- You are taking Melatonin: A study using human primary hepatocytes showed that concomitant use can cause metabolic disorder of melatonin.
- You are taking Cyclosporine: Rhubarb decreased the bioavailablity of cyclosporine in mice. Clinical relevance is not known.
- You are taking Methotrexate: Rhubarb was shown to increase exposure to methotrexate in mice. Clinical relevance is not clear.
Side Effects
For Healthcare Professionals
Clinical Summary
Rhubarb, a perennial herb, is cultivated in many parts of the world. The stalks are consumed as food, and the rhizome and root are widely used in Traditional Chinese medicine for a variety of conditions including cancer, immunosuppression, constipation, diarrhea, gastrointestinal ulcers, and hypertension (1) (3). The anthraquinones and tannins in rhubarb are thought responsible for its laxative and constipating effects, respectively (4).
Rhubarb demonstrated anticancer (20), antimetastatic (21), radioprotective (22), and estrogen receptor modulating (13) effects in preclinical studies. Limited clinical findings indicate that it may be effective in improving feeding tolerance and relieving gastrointestinal dysfunction in critically ill patients (23); in preventing the incidence of post endoscopic retrograde cholangiopancreatography pancreatitis (PEP) and hyperamylasemia in high-risk patients (24); for treating recurrent aphthous stomatitis (RAS) (25); and may benefit patients with acute organophosphorus pesticide poisoning (AOPP) (26). A rhubarb extract was shown to reduce radiation-induced lung toxicity and increased pulmonary function in lung cancer patients (7).
Aloe-emodin, one of the constituents, demonstrated anticancer (5) (6) (27) and anti-leishmanial (30) effects. It was also shown to enhance the effects of sorefenib (28) and cisplatin (29).
Rhubarb is considered to be a stimulant laxative. It is also a component of Essiac tea. Patients and physicians should be aware of the potential for additive effects.
Purported Uses
Mechanism of Action
When used in small doses, the tannin content in rhubarb has a constipating effect. At higher doses, however, the hydrolyzed metabolites of emodin and sennidin stimulate the gastrointestinal tract and produce a laxative effect (4). The actions of anthraquinones on rheinanthrone, which is transformed from sennoside A, may promote the purgative effects of sennoside A (16).
The anti-inflammatory activity of emodin may mediate rhubarb’s hepatoprotective effects in rats with cholestatic hepatitis (11). Lindeyin, a phenolic gallylglucoside, exhibits analgesic and anti-inflammatory properties in animal models. Catechin, epicatechin, procyanidins, and gallylglucose were also shown to inhibit hyaluronidase (10) (12).
Additional studies show that aloe-emodin exerts anti-proliferative activity, inducing cell cycle arrest in cancer cell lines (6). Anthraquinone extracts of rhubarb were shown to induce cytotoxicity in cancer cell lines (5) and tumor (sarcoma 37, mammary, and Ehrlich) necrosis in mice (1), although this has not been demonstrated in humans. Another study showed that emodin inhibits human cancer cell invasiveness by specifically antagonizing the adenosine 5’-triphosphate (ATP)-gated Ca(2+)-permeable channel P2X7 receptor (P2X7R) (17).
Adverse Reactions
- A case of acute crystal-induced renal failure has been reported in a type-1 diabetic patient (with normal excretory renal function) following excessive ingestion of rhubarb (18).
Herb-Drug Interactions
- Digoxin: Potassium loss due to rhubarb’s laxative effect can increase the risk of hypokalemia. (9)
- Cytochrome P450 substrates: Rhubarb induces CYP3A and CYP2D6 and can affect the intracellular concentration of drugs metabolized by these enzymes (15) (19). Clinical relevance is not known.
- Melatonin: A study using human primary hepatocytes showed that concomitant use can cause metabolic disorder of melatonin (31).
- Cyclosporine: Rhubarb decreased the bioavailablity of cyclosporine in a murine model. Clinical relevance is not known (32).
- Methotrexate: Rhubarb was shown to increase exposure to methotrexate in a murine model. Clinical relevance is not clear (33).