Oregon grape (Berberis aquifolium or Mahonia aquifolium) is a medicinal herb from the Berberidaceae plant family. Long ago, American Indian tribes in the Pacific Northwest used Oregon grape for many ailments, including stomach problems, hemorrhages, tuberculosis, and arthritis.

Some current uses of Oregon grape include treating psoriasis, improving insulin sensitivity, and lowering heart disease risk. However, additional studies are needed to confirm its effectiveness.

What Is Oregon Grape?

The Oregon grape is a bushy perennial plant with shiny leaves that resemble holly. It produces blackish-blue, unpleasant-tasting, edible berries that look like tiny grapes. The golden yellow roots of the plant are used for their medicinal properties.

The name Oregon grape is somewhat misleading because the fruit it bears is not a grape. While the plant grows in the Pacific Northwest region of the United States—including Oregon— it flourishes in many other areas of the country.

Oregon grape is available in topical products, tinctures, and capsules. Supplements can be found in herbal stores and online.

Uses of Oregon Grape

Supplement use should be individualized and discussed with a healthcare professional, such as a registered dietitian, pharmacist, or doctor. No supplement is intended to treat, cure, or prevent disease.

Oregon grape root has been used in herbal medicine to treat different disorders. Most of the published clinical research on Oregon grape involved utilizing the root of the herb in a topical (administered on the skin) cream to treat a skin condition called psoriasis. The studies have also focused on one ingredient in Oregon grape: berberine.

Psoriasis

It is believed that the alkaloid berberine, contained in Oregon grape, is responsible for the medicinal effects when used to treat psoriasis. Further studies are needed to confirm Oregon grape’s effectiveness in treating this condition.

Diabetes Mellitus

Lab and animal studies suggest berberine improved insulin sensitivity and secretion, and other outcomes, like inflammation, in cell cultures of mice.

It is thought that berberine may improve blood sugar management through several pathways, including increasing insulin sensitivity, protecting the cells that produce insulin, and decreasing sugar production in the liver (gluconeogenesis).

However, there is not enough human data suggesting that berberine alone is effective in treating diabetes.

Heart Disease

Berberine may lower the risk of heart disease by improving cholesterol levels and/or reducing inflammation associated with cardiovascular disease. In animal studies, berberine lowers LDL (bad) and total cholesterol as well as reduces plaque buildup in blood vessels.

The anti-inflammatory and antioxidant properties are also thought to be heart-protective. However, clinical studies are needed to confirm berberine has similar heart-protective effects in humans.

Other Potential Uses

Oregon grape has also been used for its:

• Digestive properties (reducing symptoms in gastrointestinal disorders such as irritable bowel syndrome and ulcerative colitis)
• Antimicrobial properties (including its anti-fungal, antibacterial, and anti-parasitic action)
• Immune-boosting properties
• Anti-inflammatory properties

What Are the Side Effects of Oregon Grape?

Oregon grape is generally considered safe. It has no toxicity. However, several side effects have been reported from the use of Oregon grape. Along with these side effects, as with all herbal supplements, is the possibility of an allergic reaction.

Common Side Effects

Common side effects identified in Oregon grape and berberine include:

• Diarrhea
• Constipation
• Gas
• Stomach upset
• Itching, burning, and irritation (at the site of topical cream administration)
• Rash (particularly with topical use)

Severe Side Effects

Severe side effects of Oregon grape are rare. An allergy to Oregon grape’s constituents could cause anaphylaxis, a severe, life-threatening allergic reaction, but again this is rare.

Consuming too much Oregon grape, particularly too much berberine, may have severe effects, such as jaundice (yellowing of the skin) when taken in high doses.

Precautions

Oregon grape is not recommended for pregnant people because it can cross the placenta and might harm the fetus. A condition called kernicterus, a rare type of brain damage, may result if a newborn child who has jaundice is exposed to berberine. Nor is it safe for those who are breastfeeding people because berberine can be transferred to the infant through breast milk and it might cause harm.

Safety has not been established for use in children and, therefore, is not recommended.

Avoid Oregon grape if you have an allergy to other herbs in the Berberidaceae family.

The long-term internal use of Oregon grape has not been studied. Until there is clinical data on the safety of long-term use, it is not recommended to take Oregon grape internally for an extended period.

Dosage: How Much Oregon Grape Should I Take?

The berries of the plant (which are not grapes) are edible, but they taste nothing like grapes. Keep in mind that there is limited scientific evidence on the safety of Oregon grape when ingested. Unlike the Oregon grape root, the berries are not thought to offer medicinal properties.

Few clinical studies about the proper dosage of Oregon grape have been completed. There is insufficient data to determine an effective, safe dose of Oregon grape.

However, there are clinical studies on the oral consumption of berberine.

Berberine is an active ingredient in Oregon grape. A dose of 0.2 to one gram of berberine per day in tablet or capsule forms has safely been used for up to three months.

What Happens if I Take Too Much Oregon Grape?

Due to a lack of clinical data, an effective, safe dose of Oregon grape has not been determined. There is no information on upper limits specific to Oregon grape.

Research regarding the excessive use of berberine is in its early stages and has only been conducted in animals. The known effective dose for humans is not known.

Speak with your healthcare provider about what dosage of Oregon grape would be best for you.

Interactions

Certain medicines may interact with Oregon grape and interfere with the liver’s ability to break down some medications. Anyone taking prescription medication should consult their healthcare provider before taking Oregon grape.

Examples of medications that should not be taken with Oregon grape or its component berberine include:

• Neoral, Sandimmune (cyclosporine)
• Medicines for diabetes, like metformin
• Versed (midazolam)
• Medications processed by special liver enzymes (CYP2C9, CYP2D6, CYP3A4)
• Sedatives

If the liver doesn’t properly break down certain medications, they may have increased side effects.

Interactions with supplements may include:

• Herbs or supplements that may impact blood pressure (licorice, magnesium, niacin, potassium)
• Herbs or supplements that may lower blood sugar (aloe, bitter melon, cassia cinnamon, chromium)
• Herbs or supplements that may change how blood clots (garlic, ginger, ginkgo)
• Sedating herbs or supplements (melatonin, valerian)

Always consult your healthcare provider before using Oregon grape to ensure its safety, particularly when taking other medication. This includes prescription, herbal, over-the-counter (OTC), and nutritional/medicinal supplements.

Reading a supplement’s ingredient list and nutrition facts panel is essential to know which ingredients and how much of each ingredient is included. Please review this supplement label with your healthcare provider to discuss potential interactions with foods, other supplements, and medications.

How to Store Oregon Grape

Guidance for storing and disposing of Oregon Grape can be found on the package.

The dried root of Oregon grape can be stored in food or pharmaceutical-grade polyethylene bags. Bags of dried Oregon grape roots can be stored for up to two years in a dry space away from sunlight and pests.

Storage of other forms of Oregon grape should be listed on the item’s packaging. Do not use the product beyond the recommended length of storage. If the product has been stored longer than suggested, discard the product as instructed on the packaging.

Summary

Oregon grape is a medicinal plant with a history of use in the traditional medicine practices of Native Indian tribes of the Pacific Northwest. It has been used for several human ailments and conditions, but few of these claims have been verified by clinical studies.

Researchers have studied the effects of Oregon grape’s constituent, berberine, on some health conditions. More studies are needed to confirm the benefits of berberine for diabetes mellitus, heart disease, and psoriasis.

Oregon grape is considered non-toxic but clinical studies still have to be done to understand its long-term effects, along with dosing limits.

Discuss dosing and safety considerations with a healthcare professional when taking Oregon grape. Oregon grape may interact with several medications and other supplements. Share with your healthcare provider all medicines and supplements you are taking to avoid any possible interactions with Oregon grape.