Crowberry can be used to treat flat warts, but not in an infusion. Crowberry treatment of flat warts mainly relies on its corrosive effect for external use. The topical application of the pounded kernel of opuntia, the topical application of the oil of opuntia or the topical application of the pounded opuntia mixed with burnt wine can all treat flat warts. Crow’s gall is a heat-clearing and detoxifying drug with a small poison, which can be used externally to treat corns, warts and other diseases. It can be used externally in moderation. This product is toxic to the gastrointestinal tract and liver and kidney damage, internal use need to strictly control the dose, should not be used for a long time. For external use, pay attention to protect the surrounding normal skin with adhesive tape to prevent irritation of normal skin. Use with caution in pregnant women and children. Gastrointestinal bleeding and patients with liver or kidney disease should not use. It is recommended to use Crow’s Nest under medical supervision to avoid adverse effects.