The Western varieties of Oregon grape (Berberis (or Mahonia) nervosa, M. aquifolium, M. repens, M. fremontii) are commonly used for treating stomach and digestive tract infections. Containing, berberine, Oregon grape similar to other berberine plants, is well known for its antibacterial, antiviral, and antifungal properties.
In Traditional Chinese Medicine, the varieties often used are Radix Mahonia Bealei, Mahonia Nutall, B. sargentiana, and B. thunbergii. Similar to Oregon grape, they all contain the compound berberine and are considered excellent for Clearing Heat, Draining Damp, and treating a variety of skin disorders. It is very specifically useful for treating conditions of Heat paired with Dryness, as its bitter properties release fluids in the body (bile, saliva, and enzymes.)