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Oregon Grape
What is it? Overview Usage Side Effects and Warnings

What is Oregon Grape?

The roots and bark of the shrub Mahonia aquifolium(also called Oregon grape) have traditionally been used both orally and topically to treat skin problems. They were also used for other conditions such as gastritis, fever, hemorrhage, jaundice, gall bladder disease, and cancer. In addition, Mahoniawas used as a bitter tonic to improve appetite.

According to some experts, M. aquifoliumis identical to the plant named Berberis aquifolium, but others point to small distinctions. Berberis vulgaris, commonly called barberry , is a close relative of these herbs, but is not identical.

Oregon grape is primarily used today as a topical treatment for psoriasis . Growing evidence suggests that it may help reduce symptoms, although it does not seem to be as effective for this purpose as standard medications. 1 Oregon grape has been proposed as a treatment for other skin diseases, such as fungal infections (such as athlete's foot ), eczema , and acne . 2 However, the evidence is either extremely preliminary or inconclusive. For example, a double-blind, placebo-controlled study of 88 people with eczema tested a cream containing extracts of Mahonia aquifolium, Viola tricolor, and Centella asiatica. 3 The results failed to show benefit overall.

Many studies have been performed on purified berberine, a major chemical constituent of Oregon grape and other...

Safety Issues

Oregon grape appears to be safe when used as directed. In the large open study described above, only 5 of the 443 participants reported side effects of burning, redness, and itching. 4 However, because Oregon grape contains berberine, which has been reported to cause uterine contractions and to increase levels of bilirubin, oral consumption of Oregon grape should be avoided by pregnant women. 5 Safety in young children, nursing women, or people with severe liver or kidney disease has not been established.

There is an additional concern regarding the berberine content of Oregon grape. One study found that berberine impairs metabolism of the drug cyclosporine, thereby raising its levels. 6 This could potentially cause toxicity.