Cupping therapy is a method of using suction to pull or move stagnant fluids and blood out of an injured area. Either glass or plastic cups are placed on the skin for up to 15 minutes to create the desired affects. In this simple way cupping reduces pain and relaxes tight painful muscles. Cups are also regularly placed over the lungs to stimulate lung qi and improve lung function. In this way it works to combat the early symptoms of a cold, stimulate expectoration of phlegm later in a cold and reduce the frequency of asthma attacks.