Red lips may be a normal physiological phenomenon, or it may be associated with lipitis, erythema multiforme, etc. 1. Normal physiological phenomenon: each individual’s lip color is different, some people have lighter lips, while others may have redder lips. Therefore, red lips may be a normal physiological phenomenon. 2. Lip inflammation: When using unsafe lipstick, long-term sun exposure may lead to lip inflammation, which may cause repeated dryness, flaking, swelling and pain of the patient’s lips, thus making the patient’s lips red. 3. Erythema multiforme: also known as exudative erythema multiforme, the typical clinical symptoms are mainly manifested as skin lesions with mucosal lesions. Blister-herpetic erythema multiforme will lead to erosion of the oral mucosa, with a dark red halo around it, making the patient’s lips red. There may also be other causes of red lips, and after ruling out normal physiological phenomena, the patient should consult a doctor for a clear diagnosis and treatment.