Lemon has a certain sweet and sour nature, can play a nourishing Yin moist, moisturize the effect of cough.
Drinking rock sugar lemon water, there is a certain amount of nourishing yin and dry, moistening the lungs to stop coughing, benefit from the efficacy of qi nourishing yin, can be treated with dry mouth, cough, sore throat and other symptoms of the upper sense.
(But rock sugar can not be put more, otherwise it is easy to grow phlegm)