Herb library · Herb · Rehmannia glutinosa
Rehmannia
A root from traditional Chinese medicine, used raw, dried or steamed and usually taken in formulas with other herbs. The studies in people are of those multi-herb formulas, not of rehmannia alone, and they are of low quality.
Traditional use
A common plant of north China whose root is used fresh (Shêng-ti-huang), dried (Kan-ti-huang), or washed in spirits and steamed and dried nine times over (Shu-ti-huang). Chinese medicine has prescribed it as a cooling tonic for the blood, and in fatigue, wasting conditions, bleeding and fevers. Today it is the lead herb of formulas such as Rehmannia-6, which a Hong Kong trial team calls the most used Chinese medicine formulation, and formulas led by it are studied for kidney disease with diabetes and for menopausal symptoms.
Traditional energetics
Chinese materia medica
Temperature: cool. Chinese Materia Medica: Vegetable Kingdom (1911), p. 372 (opens in a new tab)
What studies show
- Limited
Menopausal symptoms in women with breast cancer: a 2025 review of 17 randomized trials (1,139 patients) found that Chinese formulas led by rehmannia lowered symptom scores more than Western medicine, but the authors said the trials had methodological flaws and varied widely.
- Limited
Diabetes with kidney disease: in a 48-week multicenter trial of 148 adults with type 2 diabetes and chronic kidney disease, adding Rehmannia-6-based formulas to standard care slowed the decline in kidney filtration (eGFR); it did not significantly change protein in the urine. Assessors were blinded, patients were not.
- Insufficient
Rehmannia on its own: no study of the single herb in people was found; every result above is for a formula.
Be careful of
Cautions
- NoteIn the diabetes and kidney trial, adverse events were about as common with the formula as with standard care alone (31% versus 36% of participants), and the menopause review reported no severe reactions. Safety of the single herb has not been studied.
- ConditionIf you have diabetes or kidney disease, a formula should only be added to your usual care with your clinician's knowledge, never in place of it.
- PregnancyNo safety information for pregnancy or breastfeeding was found in the sources used here. Talk with your clinician first.
- Ask a clinicianTalk with a clinician or pharmacist before using this if you take prescription medicines, are pregnant or breastfeeding, or are giving it to a child.
From the old books
What herbals and dispensaries of the past printed. History, in their words.
“The root is prepared for medicine by washing clean and drying in the sun, when it presents the appearance of dark, soft, wrinkled, spindle-shaped masses”
“is made by taking juicy roots, washing in spirits, filling with the seeds of the bastard cardamom, steaming on a willow frame in a porcelain vessel, drying, and resteaming and redrying nine times.”
Sources
- Rehmannia glutinosa for perimenopausal syndrome in patients with breast cancer: A systematic review and meta-analysis (opens in a new tab) · NIH · read September 25, 2026
- Add-on Rehmannia-6-Based Chinese Medicine in Type 2 Diabetes and CKD: A Multicenter Randomized Controlled Trial (opens in a new tab) · NIH · read September 25, 2026
Reviewed September 25, 2026.