Eucommia bark (Du Zhong)

Also called Eucommia ulmoides, Eucommia ulmoides bark, Du Zhong, Duzhong, Eucommiae cortex, hardy rubber tree.

Best grade C across 4 graded outcomes Botanical Last checked

The short answer

From 4 sources

Eucommia bark (Du Zhong) is a traditional Chinese herb studied mainly for blood pressure. Small trials report drops of roughly 7-8 mmHg systolic in mildly raised blood pressure, but results are mixed: an 8-week US trial and a 12-week add-on trial in China missed their main targets. Both Chinese trials were co-authored by employees of the capsule maker.

Every graded outcome on this page

4 rows · line = participants
  1. Grade CBlood-pressure rhythm when added to usual medicinesBlood pressuren 136
  2. Grade COffice and 24-hour blood pressure in grade 1 hypertensionBlood pressuren 58
  3. Grade DBlood pressure in mildly raised blood pressure (2 weeks)Blood pressuren 30
  4. Grade DBlood pressure in mildly raised blood pressure (8 weeks, lower dose)Blood pressuren 24

Key facts

Blood pressure
In a US trial of 30 adults with blood pressure of 120-160/80-100 mmHg, 3 g/day of a standardized bark extract for 2 weeks lowered blood pressure by an average of 7.5/3.9 mmHg1
Null result at lower dose
The same paper found no blood-pressure difference between groups with 1.5 g/day for 8 weeks in 24 adults1
Chinese capsule trial
In 58 people with grade 1 hypertension, office blood pressure fell 7.6/4.7 mmHg over 4 weeks with Quanduzhong capsules; most other measures, including most 24-hour readings, did not differ from sham capsules2
Add-on to medicines
Added to usual blood-pressure medicines for 12 weeks in 136 people, the capsules did not improve blood-pressure variability, the main outcome3
Industry
Employees of the capsule maker, Jiangxi Puzheng Pharmaceutical, co-authored both Chinese trials23

What it is

Eucommia bark is the dried bark of the Chinese tree Eucommia ulmoides (Du Zhong), used in Chinese medicine and sold as an extract.

How it works

Proposed

In the US trial report, the extract reduced stimulated fat breakdown in a human fat-cell assay, which the authors read as beta-adrenergic blocking activity, and earlier rat work linked it to increased nitric oxide. Both are proposed explanations, not confirmed in people.1

Forms, side by side

2 forms named in our sources. The rest show what our data holds, and say plainly where it holds nothing yet.

Eucommia bark (Du Zhong) forms compared

2 forms
Eucommia bark (Du Zhong) forms compared: 2 forms by 3 attributes. Empty cells are labelled No data yet, or Not graded in the evidence row.
2 formsAqueous bark extract standardized to pinoresinol diglucosideQuanduzhong capsules (whole Eucommia bark extract, China)
Absorption in peopleNo human absorption data.1Not measured.2
GI toleranceNo toxicity at 1.5 g/day for 8 weeks; well tolerated at 3 g/day for 2 weeks.1Mild adverse events, no difference from sham in safety measures over 4 weeks.2
Studied forBlood pressureBlood pressure, blood-pressure rhythm
  1. Aqueous bark extract standardized to pinoresinol diglucoside
    Absorption in people
    No human absorption data.1
    GI tolerance
    No toxicity at 1.5 g/day for 8 weeks; well tolerated at 3 g/day for 2 weeks.1
    Studied for
    Blood pressure
  2. Quanduzhong capsules (whole Eucommia bark extract, China)
    Absorption in people
    Not measured.2
    GI tolerance
    Mild adverse events, no difference from sham in safety measures over 4 weeks.2
    Studied for
    Blood pressure, blood-pressure rhythm
Every cell holds data from a cited page; citation numbers link to the page that holds them.Scroll the table for every column

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

4 graded outcomes, largest study first

4 graded outcomes: 2 improved, 2 no effect. The largest, a 2025 randomized trial of 136 people on Blood-pressure rhythm when added to usual medicines, found no effect.

2. Office and 24-hour blood pressure in grade 1 hypertension: improved, 58 people23. Blood pressure in mildly raised blood pressure (2 weeks): improved, 30 people3
1. Blood-pressure rhythm when added to usual medicines: no effect, 136 people14. Blood pressure in mildly raised blood pressure (8 weeks, lower dose): no effect, 24 people4

1Blood-pressure rhythm when added to usual medicines

No effect · Grade C · RCT, 136 people, 2025

Chinese adults with essential hypertension and an abnormal day-night blood-pressure rhythm, on their usual medicines

Dose, result and source
Every graded outcome on this page, largest study first
OutcomeFoundPeopleStudyWho was studied
Blood-pressure rhythm when added to usual medicinesNo effect136Grade C · RCT, 2025Chinese adults with essential hypertension and an abnormal day-night blood-pressure rhythm, on their usual medicines
Office and 24-hour blood pressure in grade 1 hypertensionImproved58Grade C · RCT, 2022Chinese adults with low-to-moderate-risk grade 1 hypertension (3 centres)
Blood pressure in mildly raised blood pressure (2 weeks)Improved30Grade D · RCT, 2011Healthy US adults with blood pressure 120-160/80-100 mmHg
Blood pressure in mildly raised blood pressure (8 weeks, lower dose)No effect24Grade D · RCT, 2011Healthy US adults with blood pressure 120-160/80-100 mmHg
Each circle is one graded outcome on this page, numbered from the largest study down, and placed by how many people it studied (log scale). It shows who was studied and what was found, not advice about your dose.

Every graded row

4 rows

Showing 4 of 4 outcomes. Human trials only.

Grade CBlood-pressure rhythm when added to usual medicinesBlood pressureMain outcome not metRCT
n 136 · 2025

No effect No significant difference in blood-pressure variability (SD and CV) in the full or per-protocol analysis. In the subgroup not using calcium channel blockers, 24-hour diastolic variability improved more.

Design
RCT, n = 136, 2025
Population
Chinese adults with essential hypertension and an abnormal day-night blood-pressure rhythm, on their usual medicines
Form
Quanduzhong capsules added to usual medicines vs usual medicines alone
Dose
1.48 g twice daily
Duration
12 weeks
Source
Reference 3 · PubMed 41132538 (opens PubMed)
Grade COffice and 24-hour blood pressure in grade 1 hypertensionBlood pressure-7.6 / -4.7 mmHg officeRCT
n 58 · 2022

Improved Office systolic and diastolic pressure changed by -7.62 and -4.66 mmHg (p < .05) and diastolic variability improved versus control; no differences in other measures, including most 24-hour readings. Adverse events were mild.

Design
RCT, n = 58, 2022
Population
Chinese adults with low-to-moderate-risk grade 1 hypertension (3 centres)
Form
Quanduzhong capsules (Eucommia bark extract) vs sham capsules
Dose
Not stated in the abstract
Duration
4 weeks (after a 1-week sham lead-in)
Source
Reference 2 · PubMed 36703729 (opens PubMed)
Grade DBlood pressure in mildly raised blood pressure (2 weeks)Blood pressure-7.5 / -3.9 mmHgRCT
n 30 · 2011

Improved 24-hour ambulatory blood pressure fell by an average of 7.5/3.9 mmHg and the extract was well tolerated.

Design
RCT, n = 30, 2011
Population
Healthy US adults with blood pressure 120-160/80-100 mmHg
Form
Aqueous bark extract standardized to 8% pinoresinol di-beta-D-glucoside
Dose
1 g three times daily (3 g/day)
Duration
2 weeks
Source
Reference 1 · PubMed 22214253 (opens PubMed)
Grade DBlood pressure in mildly raised blood pressure (8 weeks, lower dose)Blood pressureNo differenceRCT
n 24 · 2011

No effect No difference in 24-hour ambulatory blood pressure between the two groups and no toxicity.

Design
RCT, n = 24, 2011
Population
Healthy US adults with blood pressure 120-160/80-100 mmHg
Form
Aqueous bark extract standardized to 8% pinoresinol di-beta-D-glucoside
Dose
500 mg three times daily (1.5 g/day)
Duration
8 weeks
Source
Reference 1 · PubMed 22214253 (opens PubMed)

Eucommia leaf: a different preparation

1 note

Human data on the leaf that cannot be graded for the bark.

Uncontrolled leaf-tablet study
In a 2025 single-arm Japanese study, 17 adults (9 with mild chronic kidney disease) took a Tochu (Eucommia) leaf-extract tablet for a median of 33 days; systolic blood pressure fell from 128.3 to 123.8 mmHg, mainly in those with kidney disease. Without a control group, this cannot show an effect, and it tested leaf, not bark.4

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.

Effects cluster at short durations

The two positive blood-pressure results lasted 2 and 4 weeks; the 8-week and 12-week trials missed their main outcomes.123

How we got this: Durations and outcomes in the evidence table

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

Doses studied in human trials ranged from 1.5 g/day of a standardized bark extract for 8 weeks to 3 g/day for 2 weeks; a Chinese capsule product was used at 1.48 g twice daily for 12 weeks. These are research doses, not recommendations.13

When trials measured an effect

2 outcomes
How long trials ran before effects were measured
OutcomeMeasured atBasis
24-hour blood pressureWeek 2 (end of the 3 g/day study)US standardized-extract trial, 30 adults1
Office blood pressureWeek 4 (end of trial)Quanduzhong capsules vs sham, 58 adults with grade 1 hypertension2
When each outcome was assessed in the cited trials. It is not a promise of when anyone will notice a change.

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 agents

None found in our sources.

Check with what you take

Kept on this device only

Add what you take. We list every interaction our evidence profiles cite between Eucommia bark and your picks, and between your picks.

Most cited:

Add a supplement or medicine you take to check it against Eucommia bark.

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.

Not medical advice, and no dosing advice. An empty result means no row we cite names that pair, by name or through a drug class we can link the medicine to, not that a combination is safe. Where our sources name only a group of medicines we cannot match, the cabinet says so. Ask your pharmacist before you combine supplements and medicines.

Who should be careful

4 groups
People on blood-pressure medicines
Eucommia lowered blood pressure in some trials and showed beta-blocker-like activity in a lab assay. Its use with medicines has been tested in one 12-week trial whose abstract gives no safety detail, so the combined effect is not well characterised.13
Pregnancy and breastfeeding
No reliable data. Chinese medicine has traditionally used Du Zhong to 'soothe miscarriages', but no trial has tested its safety in pregnancy or breastfeeding, the cited trials enrolled non-pregnant adults, and LactMed has no entry for Eucommia.2
Low blood pressure
Because the trials aimed to lower blood pressure, people whose blood pressure already runs low have no data supporting use.12
Liver and kidney disease
Over 4 weeks, the 58-person Quanduzhong trial found no severe liver or kidney function problems and no difference from sham capsules in safety tests. LiverTox has no Eucommia entry, and people with existing liver or kidney disease have not been studied in controlled trials.2
Talk to your pharmacist or clinician before starting a supplement, especially if you take prescription medicines.

How to read the label

What to check on the Supplement Facts panel.

How to read the label

2 checks
Bark vs leaf

Eucommia leaf and bark are both used in teas, but the cited trials tested bark extracts. Leaf products are a different preparation.12

Standardization

The US trial used an extract standardized to 8% pinoresinol di-beta-D-glucoside; most labels do not state a marker compound.1

Have the bottle? Photograph its Supplement Facts panel and see each line, eucommia bark (du zhong) included, beside the doses and forms the trials used in Label X-Ray.

Frequently asked questions

Short answers to common questions; the numbers link to the sources below.

Common questions

5 answers
Does Eucommia lower blood pressure?

Possibly, modestly. Two short trials reported drops of about 7-8 mmHg systolic, but an 8-week trial and a 12-week add-on trial missed their main outcomes, and two trials were co-authored by the manufacturer.123

Is Eucommia bark safe?

Trials of 2-12 weeks reported no toxicity and only mild adverse events. Longer-term safety and use in pregnancy have not been studied.12

Can it be combined with blood-pressure medicines?

Only one trial added it to usual medicines, and its abstract gives no safety detail. Because both lower blood pressure, the combination is not well characterised.3

Is Eucommia leaf tea the same as the bark?

No. The controlled blood-pressure trials tested bark extracts. The leaf has only an uncontrolled 17-person Japanese study of a leaf-extract tablet, in which systolic pressure fell from 128.3 to 123.8 mmHg over about a month.124

What is Du Zhong used for?

In Chinese medicine it is a tonic for muscles, bones and the kidneys. In modern trials it has mainly been studied for mildly raised blood pressure.21

Sources

4 sources: trial abstracts, NIH fact sheets and reference databases. Numbers in the text link here.

Sources cited on this page

4 sources
  1. 1A clinical trial testing the safety and efficacy of a standardized Eucommia ulmoides Oliver bark extract to treat hypertension.RCT Altern Med Rev, 2011 · PMID 22214253
  2. 2Quanduzhong capsules for the treatment of grade 1 hypertension patients with low-to-moderate risk: A multicenter, randomized, double-blind, placebo-controlled clinical trial.RCT Front Pharmacol, 2022 · PMID 36703729
  3. 3Efficacy of Quanduzhong capsules in regulating blood pressure circadian rhythm in essential hypertension: a multicenter, randomized, add-on controlled clinical trial.RCT Front Pharmacol, 2025 · PMID 41132538
  4. 4An Exploratory Single-Arm Clinical Trial on Eucommia Ulmoides Leaf Extract Effects on Blood Pressure, Oxidative Stress, and Atrial Natriuretic Peptide (ANP) in Individuals With and Without Chronic Kidney Disease.Open-label trial Int J Nephrol, 2025 · PMID 40575587

What changed

Every dated change to this page: what changed, who made it and why.

Change log

2 entries
Dated changes to this page
DateChangeWho and why
who should avoid, time to effect, research notes, FAQ, questions, relatedSearched PubMed for 2023–2026 Eucommia trials and reviews: no new controlled bark trial or meta-analysis beyond the 2025 Quanduzhong add-on trial already in the table. Added a pregnancy note that records no data (no LactMed entry) and the traditional use in pregnancy stated in the 2022 trial, a liver and kidney note from that trial's safety tests (no LiverTox entry), time-to-effect rows, a 2025 uncontrolled leaf-extract study as an ungraded research note, an FAQ on leaf versus bark, page questions and goal-hub and methodology links. Interactions checked: no documented drug interactions in PubMed, LactMed or LiverTox, so the list stays empty; the blood-pressure-medicine caution remains under who should be careful.Writer: Kymata Health EditorialTrigger: A–Z audit against docs/supplements/AUDIT-STANDARD.md
allInitial editorial evidence review (first draft). Every PMID checked against NCBI E-utilities esummary (titles and years taken from the record, none retracted) and the abstract read for each cited row. Studied doses are reported as research doses, not dosing advice.Writer: Kymata Health EditorialTrigger: new page

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