Pregnancy is associated with a variety of normal physiological skin changes as well as excerbation of pre-existing skin diseases or development of new pregnancy-specific dermatoses due to hormonal fluctuations. The various skin conditions and lesions may complicate the process of differential diagnosis. In this clinical case, a 41-year-old woman experienced itching, without rashes during the third trimester of pregnancy. The symptom after delivery grew worse instead of resolving. In addition to intense itching, macules appeared on legs gradually enlarged and coalesced to form patches. We treated the patient with Tiao Wei Cheng Qi Tang (Powder) and Huang Lian Jie Du Tang (Powder) as Lu Zixian's "Six Causes Discrimination" in Qing Dynasty mentioned that "macules are caused by Yangming heat". Skin condition improved significantly within one month after intervention, thus we report the case.