Patients treated with Isotretinoin for at least 2 months with doses ranging from 20 mg-40 mg per day were treated with Co2 ablative laser on one side of the face (randomized). Patients will be treated with a single session using the fractional AcuPulse CO2 laser (AcuPulse; Lumenis Inc., Santa Clara, CA), with the AcuScan120™ scanner hand-piece and the Deep FX mode. The treatment areas will be cleansed with a mild cleanser and 70% alcohol. Local anesthesia, comprising a topical eutectic mixture of 2.5% lidocaine hydrochloric acid and 2.5% prilocaine cream (EMLA Cream; Astra Zeneca AB, Sweden), will be applied to the treated side of the face under occlusion before laser therapy. After an hour of application, the anesthetic cream will gently be removed, and then, to obtain a completely dry skin surface.Treatment parameters will be a flounce of 15 mj and density of 15% in single-pass treatment without overlapping pulse. Immediately after the treatment, gauzes moistened with cold saline solution must be gently applied (without rubbing) on the skin for 15-20 minutes. Thereafter a thin layer of mupirocin 2% ointment (TEVA PHARMACEUTICAL INDUSTRIES LTD, ISRAEL) will be applied on the skin.

After the procedure, a visual analog scale (VAS) will be used to determine the amount of pain felt by the participants. No pain will be scored as 0, and intolerable pain will be scored as 10 in this scale. Photographs will be taken at baseline; before each treatment; and 6 months after the last treatment. Acne scars will be graded by using the Quantitative Global Acne Scarring Grading System, which takes into account the quantity and type of scar based on a point system (13). With this grading scale, the total score can vary from 0 to 84. The overall score will be determined as the "acne scar score". All assessments will be done by two independent physicians and the mean value of the two assessments will be calculated. A 25% or less decrease in the acne scar score was defined as "mild improvement", 26-50% decrease as "moderate improvement", 51-75% decrease as "significant improvement", and over 75% as "near total improvement". Lack of decrease in the acne scar score was defined as "no change" and an increase in the score was defined as "worsening".

Subjective self-assessment by the participants were done 6 months after the last treatment and was scored as follows: - 1 as "worsening", 0 as "no change", 1 as "mild improvement", 2 as "moderate improvement", 3 as "significant improvement ", and 4 as "near total improvement". At this point, all patients will be 6 months after cessation of oral isotretinoin and will be treated with CO2 laser to the second half of the face with the same treatment parameters All patients will receive CO2 laser treatment once a month for 3 consecutive months (LASER treatment will be identical to the treatment mentioned above for the first half of the face).

The LASER treatment for the second half of the face will be also evaluated by two independent physicians and will be compared to the first side of the face which was previously treated. Both physicians will not be aware as to which side of the face is treated with laser during oral intake of isotretinoin and which side is not.