Rehmannia
At a glance
- Best for
- people using traditional Chinese medicine formulas and accepting limited modern evidence
- Typical dose
- 500–1,500 mg/day standardized extract; 9–30 g/day dried prepared root in TCM decoctions
- Time to effect
- Weeks
- Main caution
- Raw (unprepared) form is 'cold' in TCM and more likely to cause loose stools; human evidence is limited
What is it
Rehmannia refers to Rehmannia glutinosa (Chinese foxglove, dihuang), a perennial flowering plant in the Orobanchaceae family whose root is one of the most widely used herbs in traditional Chinese medicine. Three forms are distinguished in TCM and supplements: fresh (xian dihuang), dried/raw (sheng dihuang), and steamed/prepared (shu dihuang or radix rehmanniae preparata); the steamed form is darker, sweeter, and considered tonic for blood and yin. Key constituents include iridoid glycosides (catalpol and rehmannioside A-D), phenylethanoid glycosides (acteoside/verbascoside, echinacoside), polysaccharides, and stachyose. Rehmannia is a principal ingredient in classical formulas such as Liu Wei Di Huang Wan.
Is it worth it for you?
Worth considering if…
- You are following a TCM formula that includes rehmannia
- You want a traditional adjunct and accept weak modern data
- You tolerate the prepared (steamed) form well
Probably skip if…
- You want proven, standalone effects on diabetes or menopause
- You have low digestive function and react to the raw form
- You are pregnant and considering the raw form
Evidence at a glance
| Goal | Evidence | Effect | Best fit | Time |
|---|---|---|---|---|
| type 2 diabetes (adjunct) | Mixed Evidence | Modest / uncertain | adults using TCM formulas alongside standard diabetes care | Weeks |
| anti-inflammatory and autoimmune support | Mixed Evidence | Unclear | research-interested users; not a routine indication | Unclear |
Evidence for 2 uses
AI-assisted evidence assessment — talk to your doctor before relying on any single supplement.
type 2 diabetes (adjunct)
Biomarker supportSome small trials, often of multi-herb formulas containing rehmannia, report modest improvements in glycemic markers, with preclinical work pointing to iridoid glycosides such as catalpol. It is difficult to attribute effects to rehmannia specifically rather than the whole formula. Endpoints are glucose biomarkers, not diabetes complications.
Bottom line: Rehmannia-containing formulas may modestly affect glucose markers, but the evidence is weak and formula-dependent.
Evidence is mixed
Most data come from multi-herb formulas, so rehmannia's individual contribution and reproducibility are unclear.
anti-inflammatory and autoimmune support
Mechanism onlyIridoid and phenylethanoid glycosides in rehmannia (catalpol, acteoside) show anti-inflammatory and immune-modulating activity in lab and animal models. Human clinical evidence for autoimmune or inflammatory conditions is essentially absent. This is a mechanistic rationale only.
Bottom line: Anti-inflammatory effects are preclinical and mechanistic, with no established human benefit.
How to take it
- Typical dose
- 500–1,500 mg/day standardized extract
- Higher studied dose
- 9–30 g/day dried prepared root in TCM decoctions, often in multi-herb formulas
- Timing
- No established modern timing
- With food
- Either; prepared (steamed) form is better tolerated than raw
- How long to try
- Trial 8–12 weeks
What to track
- Digestive tolerance (loose stools, bloating)
- The symptom you are targeting (e.g. glucose, hot flashes)
- Appetite
Safety
Common side effects
Loose stools, Bloating, Reduced appetite (more common with raw/unprepared form)
Who should avoid it
- People with low digestive function (especially raw form)
- Pregnant or breastfeeding women (raw form; prepared form only per traditional guidance)
- Those on anticoagulants or antidiabetic drugs without supervision (theoretical)
Pregnancy & breastfeeding
Not established; traditional sources use the prepared form in some pregnancy formulas but caution against the raw form.
Interactions
Theoretical effect suggested by preclinical data; not well documented clinically
Possible additive glucose lowering suggested by preclinical data
Choosing a product
Look for
- Specifies prepared (shu di huang) vs raw (sheng di huang) form
- Stated species Rehmannia glutinosa
- Standardization to catalpol or known constituents where available
Be skeptical of
- 'Cures diabetes'
- 'Restores kidney function'
- Strong disease-cure language
References by claim
Track Rehmannia with Pilora
Set up dose reminders, check interactions, and join the community in the Pilora iPhone app.
Coming to App StoreDisclaimer: These statements have not been evaluated by the FDA. This page is educational, not a substitute for personalized medical advice. Evidence grades are AI-assisted assessments — talk to your doctor before starting any new supplement, especially if you’re pregnant, breastfeeding, on medications, or managing a chronic condition.