Lip Darkening Home A-Z Health Information Health Library A-Z Lip Darkening Overview Lip darkening refers to the discolouration of the lips, making them appear darker than their natural colour. Types Hyperpigmentation: Darkening due to excess melanin.Cyanosis: Blue or purple discolouration due to low oxygen levels. Symptoms Darkened lipsUneven lip colour Causes Sun exposureSmokingDehydrationCertain medicationsUnderlying health conditions Diagnosis Visual examination and medical history review. Treatment Topical lightening agentsQ-Switch YAG laserLifestyle changes