Goldenseal is a North American botanical with origins as a traditional remedy among Native Americans. It has historically been used for skin and eye irritations, as a bitter tonic, and to improve digestive function. It is also marketed as an antioxidant and is often combined with echinacea in supplements to support immune function.
Two of its compounds, berberine and hydrastine, have been studied in the lab. In animal studies, goldenseal compounds appeared to kill bacteria and other microbes, and slow tumor growth. Anti-inflammatory, spasm-reducing, and muscle-contracting properties have also been observed. However, other animal studies suggest potential toxicity with long-term use and there are no human data to confirm supposed effects.