嘴唇呈现异常发紫（医学称“发绀”gàn），可能是心脏供血不足或心肺功能异常的表现。嘴唇发绀常见于先天性心脏病、肺部重症或循环障碍，属明确健康警报。
Abnormally purple lips—a condition medically known as cyanosis（/ˌsaɪəˈnəʊsɪs/）
—may indicate inadequate blood supply to the heart or impaired cardiopulmonary function. Cyanosis of the lips is commonly associated with congenital heart disease, severe pulmonary conditions, or circulatory disorders, and serves as a clear health warning.