Diagnosis
A diagnosis of perioral dermatitis is typically made based on the characteristics of the rash. A skin biopsy is usually not required to make the diagnosis but can be helpful to rule out other skin diseases which may resemble perioral dermatitis. Extended patch testing may be useful to also rule out allergic contact causes.Other skin diseases that may resemble perioral dermatitis include:

Rosacea
Acne vulgaris
Seborrheic dermatitis
Allergic contact dermatitis
Irritant contact dermatitis
Angular cheilitis

Treatment
Multiple treatment regimes are available and treatment algorithms have been proposed.Perioral dermatitis will usually resolve within a few months without medication, by limiting the use of irritants, including products with fragrance, cosmetics, benzoyl peroxide, occlusive sunscreens, and various acne products. This is called zero treatment. Topical corticosteroids should be stopped entirely if possible. If the flare proves intolerable, temporary use of a less potent topical corticosteroid can often be helpful. Medication
A number of medications, either applied directly to the skin or taken by mouth, may hasten recovery. These include tetracycline, doxycycline, and erythromycin. Erythromycin may be used as a cream. Doxycycline is most often the first antibiotic drug choice, given at a daily dosage of 100 mg for up to a month before considering tapering off or stopping. Sometimes, longer duration of low doses of doxycycline are required.Metronidazole is less effective, but is available in a gel and can be applied twice daily. If the perioral dermatitis was triggered by a topical steroid then pimecrolimus cream has been suggested as effective in improving symptoms. However, this has also been documented to cause the condition.
Perioral dermatitis, also known as periorificial dermatitis, is a common type of skin rash. Symptoms include multiple small (1–2 mm) bumps and blisters sometimes with background redness and scale, localized to the skin around the mouth and nostrils. Less commonly the eyes and genitalia may be involved. It can be persistent or recurring and resembles particularly rosacea and to some extent acne and allergic dermatitis. The term "dermatitis" is a misnomer because this is not an eczematous process.The cause is unclear. Topical steroids are associated with the condition and moisturizers and cosmetics may contribute. The underlying mechanism may involve blockage of the skin surface followed by subsequent excessive growth of skin flora. Fluoridated toothpaste and some micro-organisms including Candida may also worsen the condition, but their roles in this condition is unclear. It is considered a disease of the hair follicle with biopsy samples showing microscopic changes around the hair follicle. Diagnosis is based on symptoms.Treatment is typically by stopping topical steroids, changing cosmetics, and in more severe cases, taking tetracyclines by mouth. Stopping steroids may initially worsen the rash. The condition is estimated to affect 0.5-1% of people a year in the developed world. Up to 90% of those affected are women between the ages of 16 and 45 years, though it also affects children and the elderly, and has an increasing incidence in men.