Medicated plasters are pieces of fabric that contain a layer of medication covered by a layer of adhesive. They deliver herbal infusions through the skin to underlying tissues quickly and effectively for fast relief of minor arthritis pain, backache, sore muscles, and more. Some older Chinese medicated plasters are hard and dry. They get activated by heat- with instructions to warm the plaster in a frying pan before applying! Newer plasters are flexible and peel easily on and off. They may be cut to the required shape and size. Never leave a plaster in place for a prolonged length of time. Always test for skin sensitivity before use.