Prolonged use of azelaic acid may cause rashes, dry skin, flaking and other discomforts. Azelaic acid is mainly used for the treatment of skin acne topical drugs, the main principle of action is to inhibit the protein synthesis of microorganisms, and then make the microorganisms die, to play the role of antibacterial; this drug can also make the follicle funnel part of the keratinization process into normal. However, long-term use of azelaic acid patients may cause skin dehydration, causing skin dryness, severe cases of rash, burning pain, flaking and so on. A small number of patients may also experience metamorphic reactions, which can be manifested as skin pigmentation reduction, leukoplakia and other skin diseases. So azelaic acid in the continuous use of 12 weeks after the skin condition does not improve the situation, need to consult a doctor. Azelaic acid needs to be used under the guidance of a doctor, do not use privately, if there is discomfort, consult a doctor in time.