Phellodendron (Amur Cork Tree Bark)

Also called Phellodendron amurense, Amur cork tree, Phellodendri cortex, phellodendron bark, NP 06-1.

Best grade D across 5 graded outcomes Botanical Last checked

The short answer

From 9 sources

Phellodendron bark reaches supplements almost only in blends, mainly Relora with magnolia bark. Four small trials, all sponsored by blend maker Next Pharmaceuticals, report less temporary anxiety, lower cortisol or better knee scores. Phellodendron alone has been studied only for tolerance, in 21 men with prostate cancer. No federal or regulatory agency has reviewed its safety.

Every graded outcome on this page

5 rows · line = participants
  1. Grade DSalivary cortisol and mood in moderately stressed adultsStressn 56
  2. Grade DKnee osteoarthritis pain and function (Lequesne index)Jointsn 45
  3. Grade DLipids, blood pressure and weightHeart markersn 45
  4. Grade DAnxiety, cortisol and sleep in stressed womenStressn 40
  5. Grade DWeight change in stress eatersWeightn 28

Key facts

What it is
Bark of Phellodendron amurense, used in traditional Chinese medicine; its bioactive compounds include berberine and palmatine1
How it is sold
Mostly in Relora, a proprietary magnolia and phellodendron bark blend, or NP 06-1, a phellodendron bark and sweet orange peel blend25
Cortisol
In 56 moderately stressed adults, 4 weeks of Relora lowered salivary cortisol exposure by 18% vs placebo4
Anxiety
Relora at 750 mg/day eased temporary (state) anxiety but not trait anxiety, cortisol or sleep in a 6-week pilot (26 of 40 women completed)2
Funding
Every trial in our sources was funded by Next Pharmaceuticals, the maker of both blends2345
Agency safety reviews
No ODS, NCCIH, LactMed, LiverTox, Health Canada or EMA source covers phellodendron7

What it is

Phellodendron amurense bark is a traditional Chinese medicine ingredient containing berberine and palmatine, sold mainly in blends.

How it works

Proposed

Phellodendron bark contains berberine and palmatine, which show anti-inflammatory and antioxidant activity in laboratory research. Relora trial authors attribute its effects to lower cortisol, but phellodendron's share of any blend effect is unknown.134

Forms, side by side

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

Phellodendron (Amur Cork Tree Bark) forms compared

3 forms
Phellodendron (Amur Cork Tree Bark) forms compared: 3 forms by 3 attributes. Empty cells are labelled No data yet, or Not graded in the evidence row.
3 formsMagnolia + phellodendron blend (Relora)Phellodendron + sweet orange peel blend (NP 06-1)Phellodendron bark extract alone (e.g., Nexrutine)
Absorption in peopleNo human absorption data in our sources.2No human absorption data in our sources.5No human absorption data in our sources.1
GI toleranceNo significant adverse events in 6-week trials at 750 mg/day.23No serious adverse events over 8 weeks at 1,480 mg/day.5In an uncontrolled study of 21 men with prostate cancer, 500 mg three times daily for 1–2 months caused two transient grade 3 side effects (low potassium, urinary incontinence) and no grade 4 events.9
Studied forStress, temporary anxiety, cortisol, weight in stress eatersKnee osteoarthritis scores and cardiovascular markersTolerance before prostate cancer surgery or radiation (uncontrolled); no controlled single-ingredient trials
  1. Magnolia + phellodendron blend (Relora)
    Absorption in people
    No human absorption data in our sources.2
    GI tolerance
    No significant adverse events in 6-week trials at 750 mg/day.23
    Studied for
    Stress, temporary anxiety, cortisol, weight in stress eaters
  2. Phellodendron + sweet orange peel blend (NP 06-1)
    Absorption in people
    No human absorption data in our sources.5
    GI tolerance
    No serious adverse events over 8 weeks at 1,480 mg/day.5
    Studied for
    Knee osteoarthritis scores and cardiovascular markers
  3. Phellodendron bark extract alone (e.g., Nexrutine)
    Absorption in people
    No human absorption data in our sources.1
    GI tolerance
    In an uncontrolled study of 21 men with prostate cancer, 500 mg three times daily for 1–2 months caused two transient grade 3 side effects (low potassium, urinary incontinence) and no grade 4 events.9
    Studied for
    Tolerance before prostate cancer surgery or radiation (uncontrolled); no controlled single-ingredient trials
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

5 graded outcomes, largest study first

5 graded outcomes: 4 improved, 1 mixed. The largest, a 2013 randomized trial of 56 people on salivary cortisol and mood in moderately stressed adults, found an improvement.

1. Salivary cortisol and mood in moderately stressed adults: improved, 56 people12. Knee osteoarthritis pain and function (Lequesne index): improved, 45 people23. Lipids, blood pressure and weight: improved, 45 people35. Weight change in stress eaters: improved, 28 people5
4. Anxiety, cortisol and sleep in stressed women: mixed, 40 people4

1Salivary cortisol and mood in moderately stressed adults

Improved · Grade D · RCT, 56 people, 2013

Adults screened for moderate stress (35 men, 21 women)

Dose, result and source
Every graded outcome on this page, largest study first
OutcomeFoundPeopleStudyWho was studied
Salivary cortisol and mood in moderately stressed adultsImproved56Grade D · RCT, 2013Adults screened for moderate stress (35 men, 21 women)
Knee osteoarthritis pain and function (Lequesne index)Improved45Grade D · Pilot RCT, 2009Overweight and normal-weight adults with knee osteoarthritis in 4 groups (80 enrolled, 45 completed)
Lipids, blood pressure and weightImproved45Grade D · Pilot RCT, 2008Same 80 adults with knee osteoarthritis (45 completed)
Anxiety, cortisol and sleep in stressed womenMixed40Grade D · Pilot RCT, 2008Overweight premenopausal women aged 20 to 50 who eat in response to stress (40 intent-to-treat, 26 completed)
Weight change in stress eatersImproved28Grade D · Pilot RCT, 2006Overweight premenopausal women who eat in response to stress (28 completers)
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

5 rows

Showing 5 of 5 outcomes. Human trials only.

Grade DSalivary cortisol and mood in moderately stressed adultsStressCortisol -18%RCT
n 56 · 2013

Improved Salivary cortisol exposure was 18% lower than with placebo; overall stress (-11%), tension, depression, anger, fatigue and confusion scores were lower, and global mood and vigour higher.

Design
RCT, n = 56, 2013
Population
Adults screened for moderate stress (35 men, 21 women)
Form
Relora (magnolia + phellodendron bark blend)
Dose
Not stated in the abstract
Duration
4 weeks
Source
Reference 4 · PubMed 23924268 (opens PubMed)
Grade DKnee osteoarthritis pain and function (Lequesne index)JointsImprovedPilot RCT
n 45 · 2009

Improved Lequesne scores improved vs placebo in both weight groups (overweight: 6.3 vs 11.8); CRP fell vs placebo in the overweight group; both treatment groups lost weight (about 5% in the overweight group), which may have contributed.

Design
Pilot RCT, n = 45, 2009
Population
Overweight and normal-weight adults with knee osteoarthritis in 4 groups (80 enrolled, 45 completed)
Form
NP 06-1 (phellodendron bark + sweet orange peel extracts)
Dose
Two 370 mg capsules twice daily (1,480 mg/day)
Duration
8 weeks
Source
Reference 5 · PubMed 19682376 (opens PubMed)
Grade DLipids, blood pressure and weightHeart markersImprovedPilot RCT
n 45 · 2008

Improved Triglycerides and LDL fell and HDL rose vs placebo in both weight groups; blood pressure decreased; fasting glucose fell in the overweight group; both treatment groups lost weight.

Design
Pilot RCT, n = 45, 2008
Population
Same 80 adults with knee osteoarthritis (45 completed)
Form
NP 06-1 (phellodendron bark + sweet orange peel extracts)
Dose
Two 370 mg capsules twice daily (1,480 mg/day)
Duration
8 weeks
Source
Reference 6 · PubMed 18492265 (opens PubMed)
Grade DAnxiety, cortisol and sleep in stressed womenStressMixedPilot RCT
n 40 · 2008

Mixed State (temporary) anxiety fell vs placebo; trait anxiety, salivary cortisol and amylase, appetite, body measures and sleep quality did not differ. No significant adverse events.

Design
Pilot RCT, n = 40, 2008
Population
Overweight premenopausal women aged 20 to 50 who eat in response to stress (40 intent-to-treat, 26 completed)
Form
Relora (magnolia + phellodendron bark blend)
Dose
250 mg three times daily (750 mg/day)
Duration
6 weeks
Source
Reference 2 · PubMed 18426577 (opens PubMed)
Grade DWeight change in stress eatersWeightImprovedPilot RCT
n 28 · 2006

Improved The placebo group gained an average 1.5 kg while the treatment group did not change; 75% of controls vs 37% on treatment gained 1 kg or more. The cortisol difference was a non-significant trend.

Design
Pilot RCT, n = 28, 2006
Population
Overweight premenopausal women who eat in response to stress (28 completers)
Form
Magnolia + phellodendron bark extracts (Relora)
Dose
250 mg three times daily (750 mg/day)
Duration
6 weeks
Source
Reference 3 · PubMed 16454147 (opens PubMed)

Phellodendron alone: a tolerance study

1 note

Human data outside the graded table.

Prostate cancer tolerance study (uncontrolled)
21 men received Phellodendron amurense bark extract (Nexrutine) 500 mg three times daily for 1–2 months before surgery or with radiation. There were two transient grade 3 side effects and no grade 4 events; PSA fell in 81% by the end of the pre-treatment phase. With no control group, this measures tolerance, not benefit.9

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.

One sponsor, no single-ingredient data

All four efficacy trials (five reports) were funded by Next Pharmaceuticals and tested blends; the only single-ingredient human data are an uncontrolled 21-person tolerance study, so there is no independent controlled evidence.23459

How we got this: Funding statements and interventions in each cited paper

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 750 mg a day of the magnolia-phellodendron blend Relora for 6 weeks to 1,480 mg a day of a phellodendron-orange peel blend for 8 weeks; the abstracts do not state how much phellodendron the blends contain. No controlled trial gave phellodendron alone; an uncontrolled tolerance study used 500 mg of bark extract three times daily.2359

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.

What Phellodendron meets

1 cited row 5 tested together

Medicines 1

Phellodendron1 medicine · 1 supplement

Supplements and foods 1

  • Reference summary
  • Tested together in a graded trial
Also cited: 5 tested together

  1. Warfarin

    • ReviewReference summary

      Warfarin, for example Coumadin, Jantoven: A 2024 review of herb–warfarin interactions reports that Phellodendron amurense competes with warfarin for binding to blood proteins. This can raise the amount of free warfarin in the blood and strengthen its anticoagulant effect.

      Source 8, Curr Drug Metab (2024)

  2. Magnolia barkMagnolia bark page

Rows as our evidence profiles cite them; links stay on this site. Line weight shows what backs a row, not how serious an interaction is. No line means none was found in our sources, not that a combination is safe. Not medical advice: ask your pharmacist.

Interactions

1 agent
Published interactions, grouped by kind
AgentWhat the source saysEvidence
Medicines1
Warfarine.g. Coumadin, JantovenA 2024 review of herb–warfarin interactions reports that Phellodendron amurense competes with warfarin for binding to blood proteins. This can raise the amount of free warfarin in the blood and strengthen its anticoagulant effect.8Review

Check with what you take

Kept on this device only

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

Most cited:

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

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

3 groups
People on medicines
No ODS, NCCIH, LactMed, LiverTox, Health Canada or EMA source covers phellodendron. NCCIH notes that dietary supplements may interact with medications. Phellodendron contains berberine, which has its own page. In a small tolerance study of the extract alone, grade 3 low blood potassium was one of two transient side effects.719
Pregnancy, breastfeeding and children
No trial studied these groups, and NCCIH notes that many dietary supplements have not been tested in pregnant women, nursing mothers or children.7
Before surgery
NCCIH advises telling your health care providers about all supplements well before an operation.7
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
Blend, not bark

Trials used 750 mg a day of Relora, a proprietary blend; the phellodendron share is not stated.23

Different blends, different data

The knee and heart-marker results come from NP 06-1 (phellodendron plus orange peel), not from Relora.56

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

Where to buy Phellodendron (Amur Cork Tree Bark)

Products from brands we partner with that contain Phellodendron (Amur Cork Tree Bark). Check the amount per serving against the doses studied above, and the label for other ingredients.

Phellodendron (Amur Cork Tree Bark) products from partner brands

1 product
  • HerbsProNOW Foods Relora, 300 mg, 120 Vcaps

    1 veg capsule: 300 mg Relora (proprietary blend of Magnolia officinalis bark extract and Phellodendron amurense bark extract); phellodendron amount not stated

    $24.99one-timeChecked Oct 15, 2026
    Shop at HerbsPro (paid link, opens in new tab)

Listing a product is not a claim that it works; check the amount per serving against the doses studied, and the label for other ingredients.Prices and labels are from each brand’s own site on the date shown; confirm before you buy.

Partner links may earn us a commission. How partner links work

Frequently asked questions

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

Common questions

6 answers
What is phellodendron used for?

Its bark is a traditional Chinese medicine ingredient. In supplements it appears mainly in Relora, a blend with magnolia bark marketed for stress.12

Does Relora lower stress or cortisol?

Results are mixed. A 56-person trial found 18% lower cortisol exposure, while two smaller pilots found no significant cortisol change; one reported less temporary anxiety. All were funded by Relora's maker.234

Does phellodendron help knee osteoarthritis?

One 8-week pilot of a phellodendron-orange peel blend improved knee pain and function scores, but only 45 of 80 people finished, participants also lost weight, and the sponsor made the product.5

Is phellodendron safe?

Short trials of blends reported no serious adverse events, and an uncontrolled study of the bark extract alone (1,500 mg/day for 1–2 months, 21 men) found two transient grade 3 side effects. No federal or regulatory agency has reviewed phellodendron.2597

Is phellodendron safe during pregnancy or breastfeeding?

There are no data. No trial included pregnant or breastfeeding women, no LactMed record exists, and NCCIH notes that many supplements have not been tested in these groups.7

Does phellodendron contain berberine?

Yes. Berberine and palmatine are among the bioactive compounds in Phellodendron bark.1

Sources

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

Sources cited on this page

9 sources
  1. 1Protective Effects of Phellodendron Species on Bone Health: A Novel Perspective on Their Potentials in Treating Osteoporosis and Osteoarthritis.Review Chin J Integr Med, 2024 · PMID 38157118
  2. 2Effect of a proprietary Magnolia and Phellodendron extract on stress levels in healthy women: a pilot, double-blind, placebo-controlled clinical trial.Pilot RCT Nutr J, 2008 · PMID 18426577
  3. 3Effect of a proprietary Magnolia and Phellodendron extract on weight management: a pilot, double-blind, placebo-controlled clinical trial.Pilot RCT Altern Ther Health Med, 2006 · PMID 16454147
  4. 4Effect of Magnolia officinalis and Phellodendron amurense (Relora®) on cortisol and psychological mood state in moderately stressed subjects.RCT J Int Soc Sports Nutr, 2013 · PMID 23924268
  5. 5Phellodendron and Citrus extracts benefit joint health in osteoarthritis patients: a pilot, double-blind, placebo-controlled study.Pilot RCT Nutr J, 2009 · PMID 19682376
  6. 6Phellodendron and Citrus extracts benefit cardiovascular health in osteoarthritis patients: a double-blind, placebo-controlled pilot study.Pilot RCT Nutr J, 2008 · PMID 18492265
  7. 7Using Dietary Supplements WiselyFact sheet National Center for Complementary and Integrative Health (NCCIH), 2019 · nccih.nih.gov
  8. 8Safety Issues of Herb-Warfarin Interactions.Review Curr Drug Metab, 2024 · PMID 38465436
  9. 9Tolerance of Phellodendron amurense bark extract (Nexrutine®) in patients with human prostate cancer.Open-label trial Phytother Res, 2015 · PMID 25205619

What changed

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

Change log

3 entries
Dated changes to this page
DateChangeWho and why
summary, forms, studied doses, research notes, who should be careful, FAQSearched PubMed for phellodendron and Relora trials and meta-analyses through 2026; no new controlled trial found. Corrected the claim that phellodendron was never tested alone: added an uncontrolled 21-man tolerance study of Phellodendron amurense bark extract (Nexrutine, PMID 25205619) to the forms table, research notes and safety text. Added a pregnancy FAQ. MSKCC About Herbs has no phellodendron page; LactMed has no record.Writer: Kymata Health EditorialTrigger: A–Z page audit
InteractionsAdded a warfarin interaction entry from a 2024 review of herb–warfarin interactions (plasma-protein binding). PMID checked with NCBI esummary; wording kept to the abstract.Writer: Kymata Health EditorialTrigger: Update
allInitial editorial evidence review. Every PMID checked against NCBI E-utilities esummary (title and year) and each cited abstract read; numbers taken from the abstracts (and, where noted, the full text for funding and participant counts). Industry funding disclosed: every trial was funded by Next Pharmaceuticals (Relora and NP 06-1 maker). No agency source covers phellodendron, so safety text cites NCCIH's Using Dietary Supplements Wisely. Where to buy: NOW Foods Relora 300 mg (product page and label checked 2026-10-15).Writer: Kymata Health EditorialTrigger: new page

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