Goldenseal, Hydrastis canadensis L., is a herb that is widely used in dietary supplements, eye washes, and skin lotions. Goldenseal works as contact antimicrobial rather than a general antibiotic. It can be applied directly to open sores or inflamed skin for its soothing effect on inflamed mucous membranes, skinlike linings that protect many of the body's organs. Goldenseal is often used to treat bladder infections. Berberine extracts and decoctions (extracts obtained through boiling) have demonstrated significant antimicrobial activity against a variety of organisms including bacteria, viruses, fungi, protozoans, helminths, and chlamydia.
The plant is also used for reducing inflammation from sores and ulcers of the mouth and eyes. Pets with allergic conjunctivitis (runny eyes) may benefit from eye drops made from goldenseal. Its active component, berberine is helpful in treating tapeworms (in conjunction with garlic and for treating giardial and E. coli infections of the intestinal tract. In animal experiments goldenseal has shown powerful anticancer activity against brain tumors. In humans goldenseal has shown evidence of being effective in lowering LDL (bad cholesterol) levels. Goldenseal may enhance immune function by increasing antigen-specific immunoglobulin production. Due to similar qualities (and the fact that goldenseal is an endangered plant), Oregon grape, and goldenthread can be used in place of goldenseal.
Goldenseal should not be used in pregnant animals or in pets with low blood sugar levels (as goldenseal further lowers blood sugar). Long-term use of goldenseal may cause high blood pressure and should not be used in pets with kidney failure or in cats with hyperthyroidism, in pets with jaundice or liver disease. It is recommended that goldenseal be used for no more than 7 days in a row, with a break of 5 to 7 days before resuming use, to prevent overstimulation of the liver.