Evaluation of the Efficacy and Safety of Fractional CO₂ Laser With and Without Intradermal Botulinum Toxin A in the Treatment of Inflammatory Facial Acne Vulgaris.

• Each participant will undergo a total of 3 FCO₂ laser sessions, scheduled at four-week intervals. Laser sessions will be initiated 2 weeks after intradermal microbotox injections on the designated side.
• Laser safety goggles will be used for all patients throughout the procedure.
• A fractional CO₂ laser system (10,600 nm; DEKA SmartXide DOT, Italy) will be used in all sessions. The treatment protocol comprises 2 overlapping passes over acne lesions, while perilesional and uninvolved skin will receive a single pass. Laser settings will be standardized at 15 W power, 550 μm dot spacing, 400 μs dwell time, using SmartTrack scanning mode with single stack emission. A square pattern with a 10/10 ratio and 100% spot size will be applied.
• The same laser settings will be used on both sides in each patient. If adjustment for phototype is required, it will be applied symmetrically to both sides and documented.

The treatment protocol comprises two overlapping passes over acne lesions, while perilesional and uninvolved skin receives a single pass. Laser settings were standardized at 15 W power, 550 μm dot spacing, 400 μs dwell time, using SmartTrack scanning mode with single stack emission. A square pattern with a 10/10 ratio and 100% spot size will be applied.

• FCO2
• 10,600 nm; DEKA SmartXide DOT, Italy

• A single session of intradermal microbotox injections will be performed 2 weeks prior to FCO₂ laser sessions on the allocated side.
• Topical anesthetic cream (lidocaine 2.5%/prilocaine 2.5%) will be applied to the treatment area for approximately 30 minutes prior to injection to minimize patient discomfort. Following adequate anesthesia, the anesthetic cream will be completely removed, and the skin will be disinfected with 70% isopropyl alcohol before injection.
• Botox® (onabotulinumtoxinA) will be used. Each vial containing 100 units will be reconstituted with 5 mL of sterile normal saline (0.9% NaCl), yielding a concentration of 20 units/mL.
• The diluted toxin will be administered intradermally using an insulin syringe fitted with a 30-gauge needle. Injections will be delivered at an angle of approximately 5-15° relative to the skin surface to ensure proper intradermal placement. • The total injected dose will be standardized at 20 units per hemi-face.

The treatment protocol comprises two overlapping passes over acne lesions, while perilesional and uninvolved skin receives a single pass. Laser settings were standardized at 15 W power, 550 μm dot spacing, 400 μs dwell time, using SmartTrack scanning mode with single stack emission. A square pattern with a 10/10 ratio and 100% spot size will be applied.

• FCO2
• 10,600 nm; DEKA SmartXide DOT, Italy

Intradermal botulinum toxin injection will be performed to one randomized hemi-face in each patient 2 weeks prior to starting FCO2 LASER sessions.

• Botox® (onabotulinumtoxinA), manufactured by Allergan (Irvine, California, USA), will be used. Each vial containing 100 units will be reconstituted with 5 mL of sterile normal saline (0.9% NaCl), yielding a concentration of 20 units/mL.
• The diluted toxin will be administered intradermally using an insulin syringe fitted with a 30-gauge needle. Injections will be delivered at an angle of approximately 5-15° relative to the skin surface to ensure proper intradermal placement, evidenced by the formation of small visible wheals at the injection sites. Microinjections will be spaced approximately 1 cm apart over the designated side of the face.
• The total injected dose will be standardized at 20 units per hemi-face.
• Care will be taken to avoid deep intramuscular injection to minimize the risk of unintended muscle weakness.

• Bótox

lesion count will be performed to each hemi-face respectively upon enrollment and at the end of treatment period and at the follow up visit (3 months past cessation of treatment).

With separate right and left cheek scoring in concordance with the split-face design. In 1997, Doshi et al. introduced the Global Acne Grading System (GAGS), which divides the face, chest, and back into six areas. Each area is graded from 0 to 4 based on the severity of the worst lesion. These individual scores are summed to produce a total score. Patients are classified as follows: 1-18 indicates mild acne, 19-30 indicates moderate acne, 31-38 indicates severe acne, and over 39 indicates very severe acne (Doshi, Zaheer and Stiller, 1997).

is a clinician-rated scale used to evaluate overall acne severity and treatment response based on a global assessment of lesion appearance. It grades acne from clear (0) to severe (4)

Acne-related quality of life will be assessed using the CADI, a validated acne-specific quality of life questionnaire developed by Motley and Finlay in 1992 to assess the psychological and social impact of acne vulgaris. It consists of five items scored on a four-point scale, with higher scores indicating greater impairment. It remains widely used in clinical research due to its simplicity and reliability (Motley and Finlay, 1992)

Patient satisfaction will be assessed using a 5-point Likert scale to evaluate patients' subjective perception of treatment outcomes. On the Likert scale, patients will rate their overall satisfaction as 1 = very dissatisfied, 2 = dissatisfied, 3 = neutral, 4 = satisfied, and 5 = very satisfied.

is a validated scoring system developed to assess the severity of PIH based on lesion number, size, intensity, and distribution, with weighted scores assigned to each domain. The total PAHPI score ranges from 6 to 22, with higher scores indicating greater severity of post-acne hyperpigmentation. The index has demonstrated good reliability and validity in evaluating post-inflammatory hyperpigmentation associated with acne vulgaris (Khee et al., 2021).

is a clinician-based assessment tool used to evaluate the severity and extent of post-acne erythema following inflammatory acne lesions. It provides a standardized clinical evaluation of erythematous post-acne changes (Shucheng et al., 2024).