Acne is one of the most common conditions that patients seek for help in dermatological clinic. Nowadays, conventional treatment including topical agents(retinoids, antibiotics ,antiseptics and keratolytic agents) and systemic agents( antibiotics and retinoids) give a satisfying result but not to every patient. Some patients are not well respond to conventional therapy while some patients are unable to tolerate side effects of the treatments. Therefore, interventions to reduce acne are vigorously experimented . Lights and lasers including intense pulsed light, pulsed dye laser with or without photosensitizer and infrared lasers have been found to be useful in treating active inflammatory acne. Although,pain ,downtime and poor response of comedonal acne are limitations of those lights and lasers therapy. 2940 nm Erbium:YAG laser which has both resurfacing and photothermal effects is our laser of interest to seek for its efficacy in the treatment of inflammatory acne.

Inclusion Criteria:

• Age 18 year-old to 45 year-old
• Mild to moderate severity of acne vulgaris with at least 5 active inflammatory acne lesions on each side of the face and less than 25% difference in lesion count between each side of face
• Fitzpatrick skin phototype I-IV

Exclusion Criteria:

• History or clinical presentation of hypertrophic scar or keloid
• Photoaggravated skin diseases i.e. systemic lupus erythematosus, polymorphous light eruption, solar urticaria
• Oral isotretinoin taken within the last 6 months prior to enrollment
• Topical retinoid within 4 weeks prior to enrollment
• Systemic acne therapies (oral antibiotics) within 4 week prior to enrollment