Concise answer
Around-mouth pigmentation may follow irritation, lip licking, acne, friction, sun exposure, contact allergy or another skin condition. The distribution alone cannot identify one cause.
Strong home remedies and repeated rubbing can worsen inflammation and deepen colour.
Assessment considers the lips, surrounding skin, products, symptoms and whether similar pigment appears elsewhere.
When evaluation may help
Seek review when darkening is persistent, itchy, scaly, spreading or associated with changes inside the mouth or elsewhere on the body.