For digestive conditions, barberry is often combined with other bitter herbs, such as gentian, in tincture form. Such mixtures are taken 15 to 20 minutes before a meal, usually 2–5 ml each time. As a tincture, 2–3 ml of barberry can be taken three times per day. Standardized extracts containing 5–10% alkaloids, with a total of approximately 500 mg of berberine taken each day, are preferable for preventing infections. Standardized extracts of goldenseal are a more common source of berberine, since goldenseal contains a higher concentration of berberine than barberry. An ointment made from a 10% extract of barberry can be applied topically three times per day for psoriasis. A tea/infusion can be prepared using 2 grams of the herb in a cup of boiling water. This can be repeated two to three times daily.⁹