Rhubarb Extract

Also known as: Rheum palmatum, Rheum rhabarbarum, Da Huang, rhubarb root extract, rhein, anthraquinone extract

Evidence under review. — Not yet rated

Plant-based ingredient that may help relieve constipation by promoting regular bowel movements and softer stools.

What it does

Rhubarb extract is a plant-based ingredient that may help with constipation relief. Research shows that 12.5–25 mg daily of rhubarb extract improved stool frequency, consistency, and transit time...
Evidence quality

Evidence base hasn't been formally rated yet. See research below.
Clinical dose

12.5–25 mg/day (rhein-standardized oral); 20 mg/kg/day (clinical radiotherapy context); topical doses vary by application

What the Science Says

Rhubarb extract is a plant-based ingredient that may help with constipation relief. Research shows that 12.5–25 mg daily of rhubarb extract improved stool frequency, consistency, and transit time over 30 days, likely by changing your gut bacteria and activating natural fluid secretion in your intestines. The active compounds in rhubarb (aloe-emodin, rhein, and chrysophanol) work by softening stool and improving how your digestive tract moves. Topical rhubarb preparations have also shown promise for healing cold sores at a rate comparable to prescription antiviral cream, and may help support gum health in people with diabetes when used alongside standard treatment.

What It Doesn't Do

Rhubarb extract is not a weight loss supplement. It won't detoxify your body. It cannot treat or cure cancer. Don't expect it to protect your heart or act as a general antioxidant. Benefits seen in animal studies for metabolism haven't shown up in human testing.

Evidence-Based Benefits

Rhubarb extract has shown benefit for constipation relief in a 30-day double-blind RCT, improving stool frequency, consistency, and transit time, likely via gut microbiome modulation (PMID: 36499011). Active anthraquinone components (aloe-emodin, rhein, chrysophanol) appear to soften stool by activating intestinal fluid secretion pathways and improving motility in animal models (PMID: 37907143). Topical rhubarb preparations have demonstrated efficacy comparable to acyclovir cream for herpes labialis healing time (PMID: 11799306) and showed benefit as an adjunct in treating periodontitis in diabetic patients (PMID: 30899946). One RCT also found oral rhubarb extract reduced radiation-induced lung toxicity and improved pulmonary function in lung cancer patients by lowering TGF-beta1 and IL-6 (PMID: 17870203).

Weak Evidence

Effective at: 12.5–25 mg/day (rhein-standardized oral); 20 mg/kg/day (clinical radiotherapy context); topical doses vary by application

Source: auto-research

Absorption & Bioavailability

Unknown for most applications; oral anthraquinone compounds (rhein, aloe-emodin) are the presumed active constituents but human pharmacokinetic data are not provided in the supplied papers. Topical formulations appear to deliver active compounds locally based on clinical outcomes (PMID: 11799306, 30899946).

Red Flags to Watch For

Kidney toxicity at higher doses: subchronic rat studies show pigment deposition in renal tubules and hydronephrosis at doses ≥1.62 g/kg/day, with NOAEL of 0.65 g/kg/day (PMID: 33894279)
Long-term safety concern: 2-year rat study found tubular kidney pigment deposition at 405 and 1620 mg/kg doses, and elevated ALP and blood glucose at highest dose, though no carcinogenicity was observed (PMID: 40728016)
Anthraquinone laxatives (including those in rhubarb) are associated with potential for dependency and electrolyte imbalance with chronic use — not directly addressed in these papers but a known class concern
Most human evidence is limited to small trials (n=50–149), short durations (30 days to 12 weeks), and specific populations (cancer patients, diabetics, menopausal women); generalizability is limited
No registered supplement products in NIH DSLD, indicating limited regulatory oversight of commercial formulations

Frequently Asked Questions

What does Rhubarb Extract do?

Plant-based ingredient that may help relieve constipation by promoting regular bowel movements and softer stools.

What is the effective dose of Rhubarb Extract?

12.5–25 mg/day (rhein-standardized oral); 20 mg/kg/day (clinical radiotherapy context); topical doses vary by application

Is Rhubarb Extract safe?

Kidney toxicity at higher doses: subchronic rat studies show pigment deposition in renal tubules and hydronephrosis at doses ≥1.62 g/kg/day, with NOAEL of 0.65 g/kg/day (PMID: 33894279)

What doesn't Rhubarb Extract do?

Rhubarb extract is not a weight loss supplement.

Research Sources

PubMed
NIH DSLD

This information is for educational purposes only and is not medical advice. Always consult a healthcare professional before starting any supplement regimen. Last updated: 2026-04-06