Oregon Grape Drug Interactions, Uses, Effectiveness, Safety & More
What is this page for?
First and foremost: how Oregon Grape interacts with medications. The heart of this page is the interaction list — every drug Oregon Grape is known to interact with, and how serious each one is.
But these pages have grown well beyond that into a full monograph — what Oregon Grape is, what people use it for and how strong the evidence is, its safety and side effects, and answers to the questions we’re asked most — written and reviewed by the clinical staff at HelloPharmacist. It’s educational information from our licensed clinical databases, not medical advice, and we don’t sell or endorse products. Our editorial policy
Check Oregon Grape against your medication
Add one medicationOregon Grape Drug Interactions: The Bottom Line
From the HelloPharmacist Editorial Team · Updated July 2026Based on the available evidence, the overall risk of a clinically significant Oregon Grape drug interaction appears low for most people. None of the listed interactions are rated major, and nearly all rest on theoretical or early-stage evidence rather than confirmed problems in people.
The best-supported concern involves diabetes medications, since clinical research shows berberine, a key component of Oregon grape, can lower blood sugar, which could add to the effect of these drugs. We would also keep an eye on cyclosporine, a transplant medicine with a narrow safety margin, because berberine may slow how the body clears it and raise its levels. There is also a theoretical chance of added bleeding risk with blood thinners, though this comes from lab research rather than human studies.
The long list of interacting medications looks worrying at first, but most entries exist because berberine may affect enzymes and transporters the body uses to process many drugs. These predicted effects come mainly from lab, animal, or preliminary research, and they have not been shown to cause meaningful problems for most people taking Oregon grape.
Based on HelloPharmacist’s Oregon Grape interaction data and reviewed under our editorial standards.
Drugs that interact with Oregon Grape
1219 medications have a known interaction with Oregon Grape, graded by severity. Select any drug for the full evidence-based detail.
Don’t want to scroll the list? Just ask.
Tell us the medications you take and we’ll check each one against Oregon Grape using our pharmacist-reviewed interaction data.
AI summaries are generated from our Oregon Grape interaction data for education only — always confirm with your pharmacist. How we use AI
No drugs match “”.
What Severity, Likelihood & Evidence Mean
Severity — How Serious It Can Be
- Major. Clinically significant; generally best avoided, or used only under direct professional supervision.
- Moderate. May need monitoring, a dose adjustment, or separating the times you take each one.
- Minor. Generally not clinically significant, but still worth noting and mentioning to your pharmacist.
- No known interaction. Checked against our sources with nothing documented — not the same as proven safety.
Likelihood — How Well It’s Documented
- Likely. Well-controlled human studies have demonstrated the likely existence of this interaction
- Probable. Interaction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
- Possible. Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists
- Unlikely. Interaction has been demonstrated in animal or in lab research but has been shown not to occur in humans.
Where This Data Comes From
- Interaction records are evidence-graded and sourced from the Natural Medicines database (TRC Healthcare), the same reference used by pharmacists and hospitals.
- Each drug listed above links to the full report for that exact Oregon Grape combination — clinical detail, likelihood, evidence level, and citations.
- Content is reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.
The kinds of drugs Oregon Grape affects
Every type of medication (drug category) Oregon Grape is known to interact with. Open any category for the detail — or search your exact drug in the checker above.
Anticoagulant/Antiplatelet Drugs
Theoretically, Oregon grape might increase the risk of bleeding when taken with anticoagulant or antiplatelet drugs.
In vitro and in vivo research suggests that berberine, a constituent of Oregon grape, can inhibit platelet aggregation.
Antidiabetes Drugs
Theoretically, Oregon grape might increase the risk of hypoglycemia when taken with antidiabetes drugs.
Clinical research suggests that berberine, a constituent of Oregon grape, can lower blood glucose levels.
Antihypertensive Drugs
Theoretically, Oregon grape might increase the risk of hypotension when taken with antihypertensive drugs.
Animal research suggests that berberine, a constituent of Oregon grape, can have hypotensive effects. Also, an analysis of clinical evidence suggests that taking berberine in combination with amlodipine (Norvasc) can lower systolic and diastolic blood pressure when compared with taking amlodipine alone.
Cns Depressants
Theoretically, Oregon grape might increase the sedative effects of CNS depressants.
Animal research suggests that berberine, a constituent of Oregon grape, can have sedative effects.
Cyclosporine (Neoral, Sandimmune)
Theoretically, Oregon grape might increase the effects and adverse effects of cyclosporine.
Berberine, a constituent of Oregon grape, can reduce metabolism of cyclosporine and increase serum levels. It might inhibit cytochrome P450 3A4 (CYP3A4), which metabolizes cyclosporine.
Cytochrome P450 2C9 (Cyp2C9) Substrates
Theoretically, Oregon grape might increase serum levels of drugs metabolized by CYP2C9.
Preliminary clinical evidence suggests that berberine, a constituent of Oregon grape, can inhibit cytochrome P450 2C9 (CYP2C9).
Cytochrome P450 2D6 (Cyp2D6) Substrates
Theoretically, Oregon grape might increase serum levels of drugs metabolized by CYP2D6.
In vitro research and preliminary clinical evidence suggest that berberine, a constituent of Oregon grape, can inhibit cytochrome P450 2D6 (CYP2D6).
Cytochrome P450 3A4 (Cyp3A4) Substrates
Theoretically, Oregon grape might increase serum levels of drugs metabolized by CYP3A4.
In vitro research and preliminary clinical evidence suggest that berberine, a constituent of Oregon grape, moderately inhibits cytochrome P450 3A4 (CYP3A4).
P-Glycoprotein Substrates
Theoretically, Oregon grape might increase serum levels of drugs that are P-glycoprotein (P-gp) substrates.
In vitro research suggests that Oregon grape extracts inhibit P-gp efflux.
Oregon Grape: Uses, Safety & Side Effects
Oregon grape is a shrub whose root contains berberine and related compounds. The strongest (though still modest) evidence is for topical creams that may slightly ease psoriasis; evidence for other uses is limited. Talk with your pharmacist or doctor before using it, and avoid it during pregnancy and breastfeeding.

- Scientific name
- Mahonia aquifolium
- Family
- Berberidaceae
- Part used
- Root and root bark (sometimes stem bark); berries are used in food
- Common forms
- Topical creams and ointments, tinctures, capsules, dried root extract
- Psoriasis (topical)
- Eczema and other skin conditions
- Digestive upset
- Mild skin infections
- General 'detox' or tonic use
Popular and traditional uses — not proof it works. See “Uses & effectiveness” below for the evidence.
Topical use appears generally well tolerated, but oral use is less well studied and should be approached carefully.
When used orally. Berberine, a constituent of Oregon grape, is thought to cross the placenta and may cause harm to the fetus. Kernicterus has develope...
Read the full pregnancy detailWhen used orally. Berberine and other harmful constituents can be transferred to the infant through breast milk.
Read the full breastfeeding detailPregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center). Safety guidance is general; always confirm with your pharmacist or doctor for your situation.
Overview
Oregon grape (Mahonia aquifolium) is an evergreen shrub native to the Pacific Northwest of the United States and parts of western Canada. It has glossy, holly-like leaves and clusters of blue-purple berries, and it is often planted as an ornamental shrub. It belongs to the barberry family (Berberidaceae) and is closely related to true barberry (Berberis).
In herbal traditions, the root and root bark are the main parts used. They contain yellow plant compounds called alkaloids, including berberine. People have used Oregon grape preparations for skin problems, digestive complaints, and as a general 'tonic.' Today it is most often found in topical creams and ointments, as well as tinctures and capsules.
How it works
Oregon grape root contains alkaloids such as berberine, berbamine, and oxyacanthine. In laboratory studies, berberine and related compounds show antimicrobial activity against some bacteria and fungi, and they may help calm inflammation.
For psoriasis, researchers believe these compounds may slow the rapid overgrowth of skin cells and reduce inflammation in the skin. Most of this understanding comes from test-tube and animal research, so it does not always predict how well the plant works in people.
Does Oregon Grape work?
How to read these evidence grades
Natural Medicines’ 7-point scale. We show each rating’s label word-for-word.
Possibly Effective Psoriasis
Several clinical studies suggest that topical Oregon grape extract cream modestly improves symptoms and quality of life in patients with psoriasis.
Also studied for 3 conditions — evidence insufficient to rate
Insufficient Reliable Evidence To Rate Atopic dermatitis (eczema)
It is unclear if topical Oregon grape extract cream is beneficial in patients with atopic dermatitis.
Insufficient Reliable Evidence To Rate Gastroesophageal reflux disease (GERD)
Although there has been interest in using oral Oregon grape for GERD, there is insufficient reliable information about the clinical effects of Oregon grape for this purpose.
Insufficient Reliable Evidence To Rate Peptic ulcers
Although there has been interest in using oral Oregon grape for peptic ulcers, there is insufficient reliable information about the clinical effects of Oregon grape for this purpose.
Source & disclaimer. Effectiveness ratings and evidence summaries are provided by Natural Medicines (Therapeutic Research Center) and shown as licensed. Where Natural Medicines hasn’t rated a use, HelloPharmacist’s pharmacists may add their own reviewed rating and evidence (each such entry is labeled). This is educational information, not medical advice — talk with your pharmacist or doctor before starting, stopping, or changing a supplement.
Safety & precautions
Topical Oregon grape creams appear to be generally well tolerated by most adults, with skin irritation being the main concern. Oral use is less well studied, and high amounts of berberine-containing plants can cause stomach upset and other effects.
Pregnancy: Avoid Oregon grape. Berberine-containing plants are traditionally avoided in pregnancy because of concerns they could affect the uterus or the developing baby.
Breastfeeding: Avoid use. Berberine may pass into breast milk and could be harmful to a newborn or infant.
Use caution if you have liver problems, are taking multiple medications, or are giving it to children. Because supplements are not tightly regulated, product strength and purity can vary. Always check with your pharmacist or doctor before starting Oregon grape.
Side effects
When applied to the skin, Oregon grape may cause redness, burning, itching, or rash in some people. Doing a small patch test before regular use can help.
When taken by mouth, it may cause nausea, stomach upset, or diarrhea. Eating the raw berries in large amounts may also cause digestive upset. Serious side effects are not well documented, but the oral form has not been thoroughly studied for long-term safety.
Oregon Grape: Reported Adverse Effects
Documented safety reports on Oregon Grape from the evidence-graded Natural Medicines (TRC Healthcare) database, shown word-for-word from the licensed record.
Reports by conditionSkin irritation Dermatologic
Topically, Oregon grape may cause itching, burning, and skin irritation in some patients.
- Wiesenauer M, Lydtke R. Mahonia aquifolium in patients with Psoriasis vulgaris; an intraindividual study. Phytomedicine 1996;3:231-5.
- Gulliver WP, Donsky HJ. A report on three recent clinical trials using Mahonia aquifolium 10% topical cream and a review of the worldwide clinical experience with Mahonia aquifolium for the treatment of plaque psoriasis. Am J Ther 2005;12:398-406.
Adverse-effects data: Natural Medicines, Therapeutic Research Center
Dosing
There is no official, well-established standard dose for Oregon grape. Topical products are usually applied as directed on the label, often once or twice daily to the affected skin area.
For tinctures and capsules, follow the manufacturer's instructions, since the amount of active compounds varies from product to product. Because a reliable proven dose is not established, it is best to use the lowest amount that seems helpful and to check with a pharmacist or doctor first.
Oregon Grape & Pregnancy
Oregon Grape & Breastfeeding
© 2026 Therapeutic Research Center
Pregnancy & lactation ratings: Natural Medicines, Therapeutic Research Center
References & further reading
The 21 references that drive our Oregon Grape monograph and interaction data, from the evidence-graded Natural Medicines (TRC Healthcare) database. Citations with a link open the study on PubMed or the publisher’s site.
- Wiesenauer M, Lydtke R. Mahonia aquifolium in patients with Psoriasis vulgaris; an intraindividual study. Phytomedicine 1996;3:231-5.
- Chan E. Displacement of bilirubin from albumin by berberine. Biol Neonate 1993;63:201-8. PubMed
- Janbaz KH, Gilani AH. Studies on preventive and curative effects of berberine on chemical-induced hepatotoxicity in rodents. Fitoterapia 2000;71:25-33.. PubMed
- Wu X, Li Q, Xin H, Yu A, Zhong M. Effects of berberine on the blood concentration of cyclosporin A in renal transplanted recipients: clinical and pharmacokinetic study. Eur J Clin Pharmacol 2005;61:567-72. PubMed
- Gulliver WP, Donsky HJ. A report on three recent clinical trials using Mahonia aquifolium 10% topical cream and a review of the worldwide clinical experience with Mahonia aquifolium for the treatment of plaque psoriasis. Am J Ther 2005;12:398-406. PubMed
- Zhang Y, Li X, Zou D, et al. Treatment of type 2 diabetes and dyslipidemia with the natural plant alkaloid berberine. J Clin Endocrinol Metab 2008;93:2559-65. PubMed
- Budzinski JW, Foster BC, Vandenhoek S, Arnason JT. An in vitro evaluation of human cytochrome P450 3A4 inhibition by selected commercial herbal extracts and tinctures. Phytomedicine 2000;7:273-82. PubMed
- Chatterjee P, Franklin MR. Human cytochrome p450 inhibition and metabolic-intermediate complex formation by goldenseal extract and its methylenedioxyphenyl components. Drug Metab Dispos 2003;31:1391-7. PubMed
- Shanbhag, S. M., Kulkarni, H. J., and Gaitonde, B. B. Pharmacological actions of berberine on the central nervous system. Jpn.J Pharmacol 1970;20(4):482-487. PubMed
- Wu, J. F. and Liu, T. P. [Effects of berberine on platelet aggregation and plasma levels of TXB2 and 6-keto-PGF1 alpha in rats with reversible middle cerebral artery occlusion]. Yao Xue.Xue.Bao. 1995;30(2):98-102.
- Peng, W. H., Hsieh, M. T., and Wu, C. R. Effect of long-term administration of berberine on scopolamine-induced amnesia in rats. Jpn J Pharmacol 1997;74(3):261-266. DOI
- Sabir M and Bhide NK. Study of some pharmacological actions of berberine. Ind J Physiol & Pharmac 1971;15(3):111-132.
- Tripathi YB and Shukla SD. Berberis artistata inhibits PAF induced aggregation of rabbit platelets. Phytotherapy Research 1996;10:628-630.
- Yin, J., Xing, H., and Ye, J. Efficacy of berberine in patients with type 2 diabetes mellitus. Metabolism 2008;57(5):712-717. PubMed
- Zhang, H., Wei, J., Xue, R., Wu, J. D., Zhao, W., Wang, Z. Z., Wang, S. K., Zhou, Z. X., Song, D. Q., Wang, Y. M., Pan, H. N., Kong, W. J., and Jiang, J. D. Berberine lowers blood glucose in type 2 diabetes mellitus patients through increasing insulin re
- Guo, Y., Chen, Y., Tan, Z. R., Klaassen, C. D., and Zhou, H. H. Repeated administration of berberine inhibits cytochromes P450 in humans. Eur J Clin Pharmacol 2012;68(2):213-217. PubMed
- Wei, W., Zhao, H., Wang, A., Sui, M., Liang, K., Deng, H., Ma, Y., Zhang, Y., Zhang, H., and Guan, Y. A clinical study on the short-term effect of berberine in comparison to metformin on the metabolic characteristics of women with polycystic ovary syndro
- Hermann, R. and von, Richter O. Clinical evidence of herbal drugs as perpetrators of pharmacokinetic drug interactions. Planta Med 2012;78(13):1458-1477. PubMed
- Chun YT, Yip TT, Lau KL, and et al. A biochemical study on the hypotensive effect of berberine in rats. Gen Pharmac 1979;10:177-182. PubMed
- Lan J, Zhao Y, Dong F, et al. Meta-analysis of the effect and safety of berberine in the treatment of type 2 diabetes mellitus, hyperlipemia and hypertension. J Ethnopharmacol. 2015;161:69-81. PubMed
- Fan Y, Zhou Z, Zhang L. Effect of Oregon grape root extracts on P-glycoprotein mediated transport in in vitro cell lines. J Pharm Pharm Sci 2024;26:11927. PubMed
This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.
Parts of this content are provided by the Therapeutic Research Center, LLC.
DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.
© 2021 Therapeutic Research Center, LLC
Brands that make products with Oregon Grape
151 brands in our database make a supplement containing Oregon Grape.
Supplement products with Oregon Grape
740 products in our database contain Oregon Grape. Open any to see its full ingredient list and every drug interaction we check.
Oregon Grape: Common Questions
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Is Oregon Grape safe to take during pregnancy?
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Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy
Products that contain Oregon Grape
A rotating sample of real supplements in our database that list Oregon Grape — open any to see its full ingredients and every drug interaction we check.
- Skn T1 To L3 by Thera-Zyme
- Inflama-Rest by Source Naturals
- Bio-Assist by Return Healthy
- Blood Sugar Rebalancer by Ormus Minerals
- Intestinal Cleanse by NutriONN
- Detox Drops by Native Remedies
- Berberine Root Extract by Solaray
- Oregon Grape by Herb Pharm
- YST-Dysbio Cleanz by Nutri-West
- EHB by Integrative Therapeutics
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