Rhapontic Rhubarb Extract (ERr 731)
Also called ERr 731, rhapontic rhubarb, Rheum rhaponticum, Siberian rhubarb, rhubarb root extract, Estrovera.
Best grade B across 7 graded outcomes Botanical Last checked
The short answer
From 11 sourcesERr 731, a rhapontic rhubarb root extract in a 4 mg tablet, cut menopause symptom scores and hot flushes vs placebo in two 12-week trials of about 110 perimenopausal women each. A 2025 German records study found no rise in breast cancer diagnoses. Most of the research comes from one group of authors.
Every graded outcome on this page
7 rows · line = participants- BGrade BMenopause Rating Scale (pooled)Menopause symptomsn 390
- BGrade BMenopause symptom score (confirmatory trial)Menopause symptomsn 112
- BGrade BMenopause symptom score and hot flushesMenopause symptomsn 109
- CGrade CAnxiety in perimenopauseAnxietyn 109
- DGrade DBreast cancer diagnosis in prescription usersBreast safetyn 22,744
- DGrade DHeadache/migraine, dizziness and other complaints over 52 weeksHeadachen 89
- DGrade DSymptom scores over up to 96 weeksLong-term usen 80
- 4 more graded outcomes, in the evidence chapter
Key facts
- What it is
- A special extract of Rheum rhaponticum root, sold as Phytoestrol N in Germany and, in North America, under the name Estrovera8
- Dose in trials
- One enteric-coated 4 mg tablet a day6
- Menopause score (112 women)
- MRS fell from 27.0 to 12.4 vs 27.0 to 24.0 on placebo after 12 weeks3
- Pooled (4 studies, 390 women)
- Menopause Rating Scale 15.12 points lower than control4
- Breast cancer (records study)
- No higher diagnosis rate in 5,686 users vs 17,058 non-users (OR 1.01)7
What it is
ERr 731 is a standardized extract of rhapontic rhubarb root (Rheum rhaponticum), sold for menopausal symptoms as a 4 mg tablet.
How it works
ProposedIn cell studies, ERr 731 and its aglycones activated estrogen receptor-beta but not estrogen receptor-alpha, and showed no anti-estrogen effect. Researchers propose that ER-beta activity explains the effect on menopausal symptoms; this has not been shown in people.9
Forms
Form
| Form | Standardized to | Absorption (human data) | GI tolerance | Studied for |
|---|---|---|---|---|
| ERr 731 enteric-coated tablet (Phytoestrol N, Estrovera) | 4 mg of standardized root extract6 | No human absorption data in the cited abstracts.1 | Better tolerated than placebo in the 2006 trial; in German post-marketing data, 124 adverse event reports over about 140 million daily doses, mostly hypersensitivity and stomach upset.18 | Menopause symptoms, hot flushes, anxiety in perimenopause |
What the human research says
Human trials only, one row per outcome. The form line shows what each trial actually tested. Grades follow our evidence-grading policy.
Trial map
7 graded outcomes, largest study first7 graded outcomes: 6 improved, 1 no effect. The largest, a 2025 observational study of 22,744 people on breast cancer diagnosis in prescription users, found no effect.
1Breast cancer diagnosis in prescription users
No effect · Grade D · Observational, 22,744 people, 2025
Women seen by 260 office-based gynecologists in Germany, 1993 to 2022
Dose, result and source| Outcome | Found | People | Study | Who was studied |
|---|---|---|---|---|
| Breast cancer diagnosis in prescription users | No effect | 22,744 | Grade D · Observational, 2025 | Women seen by 260 office-based gynecologists in Germany, 1993 to 2022 |
| Menopause Rating Scale (pooled) | Improved | 390 | Grade B · Meta-analysis, 2024 | Perimenopausal women in 4 studies (193 ERr 731, 197 control) |
| Menopause symptom score (confirmatory trial) | Improved | 112 | Grade B · RCT, 2009 | Perimenopausal women with menopausal symptoms |
| Menopause symptom score and hot flushes | Improved | 109 | Grade B · RCT, 2006 | Perimenopausal women with climacteric complaints |
| Anxiety in perimenopause | Improved | 109 | Grade C · RCT, 2007 | Perimenopausal women with climacteric complaints and anxiety |
| Headache/migraine, dizziness and other complaints over 52 weeks | Improved | 89 | Grade D · Open-label trial, 2026 | Perimenopausal women aged 45–55 who continued from a 12-week RCT (112 women) into a 52-week open study |
| Symptom scores over up to 96 weeks | Improved | 80 | Grade D · Open-label trial, 2009 | Women from the 2006 RCT continuing in open follow-up |
Every graded row
7 rowsShowing 7 of 7 outcomes. Human trials only.
BGrade BMenopause Rating Scale (pooled)Menopause symptomsLower symptom scoresMeta-analysis · 4 studies
n 390 · 2024
Improved MRS was 15.12 points lower with ERr 731 than control (p < 0.001); heterogeneity was high.
- Design
- Meta-analysis, 4 studies, n = 390, 2024
- Population
- Perimenopausal women in 4 studies (193 ERr 731, 197 control)
- Form
- ERr 731
- Dose
- Varied by study
- Duration
- Varied by study
- Source
- Reference 4 · PubMed 38646867 (opens PubMed)
BGrade BMenopause symptom score (confirmatory trial)Menopause symptomsLower symptom scoresRCT
n 112 · 2009
Improved MRS total fell from 27.0 to 12.4 points vs 27.0 to 24.0 on placebo (p < 0.0001), with fewer hot flushes; 11 adverse events in 5 women on ERr 731 vs 3 in 3 on placebo.
- Design
- RCT, n = 112, 2009
- Population
- Perimenopausal women with menopausal symptoms
- Form
- ERr 731 enteric-coated tablet
- Dose
- One tablet a day
- Duration
- 12 weeks
- Source
- Reference 3 · PubMed 19161045 (opens PubMed)
BGrade BMenopause symptom score and hot flushesMenopause symptomsLower symptom scoresRCT
n 109 · 2006
Improved The MRS II total score and each symptom fell more than with placebo (p < 0.0001), hot flush number and severity fell from week 4, and endometrial biopsies, bleeding and safety labs did not differ.
- Design
- RCT, n = 109, 2006
- Population
- Perimenopausal women with climacteric complaints
- Form
- ERr 731 enteric-coated tablet
- Dose
- One tablet a day
- Duration
- 12 weeks
- Source
- Reference 1 · PubMed 16894335 (opens PubMed)
CGrade CAnxiety in perimenopauseAnxietyLower anxietyRCT
n 109 · 2007
Improved Hamilton Anxiety score fell from 27.5 to 9.4 vs 25.1 to 21.6 on placebo; 33 of 39 completers on ERr 731 went from moderate or severe to slight anxiety.
- Design
- RCT, n = 109, 2007
- Population
- Perimenopausal women with climacteric complaints and anxiety
- Form
- ERr 731 enteric-coated tablet
- Dose
- One tablet a day
- Duration
- 12 weeks
- Source
- Reference 2 · PubMed 17213754 (opens PubMed)
DGrade DBreast cancer diagnosis in prescription usersBreast safetyNo increase seenObservational
n 22,744 · 2025
No effect Breast cancer diagnosis was not more likely with ERr 731 than without (OR 1.01, 95% CI 0.81 to 1.26) or vs hormone therapy (OR 0.96).
- Design
- Observational, n = 22,744, 2025
- Population
- Women seen by 260 office-based gynecologists in Germany, 1993 to 2022
- Form
- ERr 731 prescription vs none (and vs hormone therapy)
- Dose
- Prescribed doses
- Duration
- Records follow-up
- Source
- Reference 7 · PubMed 40358648 (opens PubMed)
DGrade DHeadache/migraine, dizziness and other complaints over 52 weeksHeadacheLower headache scoresOpen-label trial
n 89 · 2026
Improved Symptom severity fell in all measured domains from baseline to week 52, with notable improvements in headache/migraine and paresthesia. Because everyone took ERr 731 in the open phase, former ERr 731 and placebo groups no longer differed, except for dizziness (p = 0.0086); over 90% reported good or very good spirits at week 52.
- Design
- Open-label trial, n = 89, 2026
- Population
- Perimenopausal women aged 45–55 who continued from a 12-week RCT (112 women) into a 52-week open study
- Form
- ERr 731 tablet
- Dose
- 4 mg/day
- Duration
- 12-week RCT, then 52 weeks open-label
- Source
- Reference 6 · PubMed 42416823 (opens PubMed)
DGrade DSymptom scores over up to 96 weeksLong-term useSustained lower scoresOpen-label trial
n 80 · 2009
Improved Symptoms kept falling; women switched from placebo reached similar scores after 18 weeks, and by the end they averaged under 1.4 slight hot flushes a day with no related adverse events.
- Design
- Open-label trial, n = 80, 2009
- Population
- Women from the 2006 RCT continuing in open follow-up
- Form
- ERr 731 enteric-coated tablet
- Dose
- One tablet a day
- Duration
- 48 weeks (51 women continued to 96 weeks)
- Source
- Reference 5 · PubMed 18978638 (opens PubMed)
What the numbers add up to
Each point is worked out from the data and the sources numbered on this page, with the arithmetic shown under it. It adds no new data and is not medical advice.
Studied doses
Doses used in research, shown against the official limits. They describe the studies, not a recommendation for you.
Studied doses in research, not advice. These are amounts used in research, not personal advice. Your clinician or pharmacist can say what fits you.
Doses studied in human trials
Interactions and safety
Published interactions only: each row cites a source. No row means none was found in our sources, not that a combination is safe.
Interactions
0 agentsNone found in our sources.
Check with what you take
Kept on this device onlyAdd what you take. We list every interaction our evidence profiles cite between Rhapontic Rhubarb Extract and your picks, and between your picks.
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Add a supplement or medicine you take to check it against Rhapontic Rhubarb Extract.
Starting from one medicine? The interaction checker rates how serious each pair is, on a curated list of 19 entries for 11 medicines. This cabinet has no severity rating: it lists every interaction row our supplement pages cite.
Who should be careful
5 groups- Hormone-sensitive conditions
- ERr 731 activates estrogen receptor-beta in cell studies. A records study found no rise in new breast cancer diagnoses, but no trial tested it in women who have had breast, uterine or ovarian cancer or other estrogen-sensitive conditions; they should ask their oncologist or clinician first.97
- Allergy
- Hypersensitivity was the most common post-marketing report in Germany (74 of 124 adverse event reports).8
- Pregnancy and breastfeeding
- Trials enrolled only perimenopausal women, and the extract acts on estrogen receptors in cell studies; there are no safety data in pregnancy or breastfeeding, so it has no studied use there. LactMed's rhubarb record covers laxative rhubarb root and has no data on ERr 731; it notes reviewers advise against rhubarb root while breastfeeding because of possible laxative effects in the infant.13911
- Not garden rhubarb
- The trial extract is made from the root of rhapontic rhubarb; rhubarb stalks eaten as food are a different product.8
- Medicines and surgery
- No drug interaction studies of ERr 731 were found in our sources, so interaction data are lacking. NCCIH advises telling your health care providers about every supplement you use.10
How to read the label
What to check on the Supplement Facts panel.
How to read the label
3 checksLook for ERr 731
Brand names
ERr 731 is sold as Phytoestrol N in Germany and as Estrovera in North America.8
Frequently asked questions
Short answers to common questions; the numbers link to the sources below.
Common questions
8 answersDoes ERr 731 help hot flashes?
Does ERr 731 raise breast cancer risk?
A German records study of 5,686 users found no higher breast cancer diagnosis rate than in non-users (OR 1.01). It is observational; two authors work for Health Research Services GmbH, whose owner co-authored the ERr 731 trials.7
Does ERr 731 help menopausal anxiety?
In the 109-woman trial, Hamilton Anxiety scores fell from 27.5 to 9.4 vs 25.1 to 21.6 on placebo. This came from the same trial as the symptom results.2
What dose of rhubarb extract was studied?
One enteric-coated 4 mg ERr 731 tablet a day.6
How long does ERr 731 take to work?
Does ERr 731 interact with medicines?
Is ERr 731 safe during pregnancy or breastfeeding?
Sources
11 sources: trial abstracts, NIH fact sheets and reference databases. Numbers in the text link here.
Sources cited on this page
11 sources- 1Efficacy and safety of a special extract of Rheum rhaponticum (ERr 731) in perimenopausal women with climacteric complaints: a 12-week randomized, double-blind, placebo-controlled trial.RCT Menopause, 2006 · PMID 16894335
- 2The special extract ERr 731 of the roots of Rheum rhaponticum decreases anxiety and improves health state and general well-being in perimenopausal women.RCT Menopause, 2007 · PMID 17213754
- 3Confirmation of the efficacy of ERr 731 in perimenopausal women with menopausal symptoms.RCT Altern Ther Health Med, 2009 · PMID 19161045
- 4Efficacy evaluation of standardized Rheum rhaponticum root extract (ERr 731 (®)) on symptoms of menopause: A systematic review and meta-analysis study.Meta-analysis J Biomed Res, 2024 · PMID 38646867
- 5Long-term efficacy and safety of the special extract ERr 731 of Rheum rhaponticum in perimenopausal women with menopausal symptoms.Open-label trial Menopause, 2009 · PMID 18978638
- 6The special extract ERr 731(®) from the root of rhapontic rhubarb (Rheum rhaponticum): efficacy in headache/migraine and further climacteric complaints in women in the perimenopause.RCT Front Pharmacol, 2026 · PMID 42416823
- 7Association between Extract Rheum rhaponticum 731 (ERr 731) prescription and subsequent breast cancer.Observational Breast Cancer Res Treat, 2025 · PMID 40358648
- 8Rheum rhaponticum Extract (ERr 731): Postmarketing Data on Safety Surveillance and Consumer Complaints.Observational Integr Med (Encinitas), 2016 · PMID 27547165
- 9Activation of estrogen receptor-beta by a special extract of Rheum rhaponticum (ERr 731), its aglycones and structurally related compounds.Animal study J Steroid Biochem Mol Biol, 2007 · PMID 17692514
- 10Using Dietary Supplements WiselyFact sheet National Center for Complementary and Integrative Health (NCCIH), 2019 · nccih.nih.gov
- 11Rhubarb. In: Drugs and Lactation Database (LactMed®) (revised February 15, 2025)Database National Institute of Child Health and Human Development, 2025 · ncbi.nlm.nih.gov
What changed
Every dated change to this page: what changed, who made it and why.
Change log
2 entries| Date | Change | Who and why |
|---|---|---|
| evidence, who should be careful, label guide, FAQ | Searched PubMed for ERr 731 and Rheum rhaponticum trials through 2026. Added the 2026 report's 52-week open follow-up as a row (PMID 42416823, grade D). Pregnancy and breastfeeding note now cites LactMed (rhubarb record NBK501862), which has no data on ERr 731. No published drug interaction studies were found (PubMed, LactMed), so the interactions list stays empty and the medicines note and a FAQ say so. Label guide extended with brand names and the difference from laxative rhubarb root; three FAQs added. | Writer: Kymata Health EditorialTrigger: A–Z page audit |
| all | Initial editorial evidence review. Every PMID checked against NCBI E-utilities esummary (title, year, journal) and each cited abstract read; numbers taken from the abstracts. The 4 mg dose is from the 2026 trial report. The pooled analysis is graded B, not A, because most trials come from one maker-linked group; the anxiety paper is marked as a secondary report of the 2006 trial. Mechanism from cell data only. Where to buy: we didn’t list a product; none of the stores we checked sells ERr 731. Adversarial review 2026-10-17: pregnancy/breastfeeding and estrogen-sensitive-condition rows made explicit (no data; not tested after hormone-sensitive cancer). | Writer: Kymata Health EditorialTrigger: new page |
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