Perioral Dermatitis

Perioral dermatitis is a cluster of small red papules and pustules that ring the mouth, typically sparing a narrow border right at the lip line — that spared rim is the clearest diagnostic clue. It can extend around the nostrils and the eyes, where it takes the periorificial name. It burns and stings more than it itches, and unlike acne it produces no comedones.

The most common trigger is topical steroid use on the face, including the inhaled steroid deposited around the mouth by an asthma inhaler. Heavy occlusive products, fluoridated toothpaste and long-running elaborate routines are also implicated. The cruel part is the steroid rebound: a steroid cream calms it quickly, the rash returns worse when the cream stops, and treating that with more steroid entrenches it.

Treatment starts by stopping. Zero-therapy — dropping every active, every occlusive and every steroid, leaving only a gentle cleanser and a bland moisturiser — is the standard first step, and it usually gets worse for a week or two before it improves. Persistent cases need prescription treatment, commonly topical metronidazole or azelaic acid, or a course of oral tetracycline.

If a rash around your mouth is not responding to acne treatment, this is the diagnosis worth asking about.