A split-face comparative study between Q-switched Nd:YAG laser and fractional CO ₂ laser in patients with post-acne hyperpigmentation: A hospital-based interventional study

Objectives: Post-inflammatory hyperpigmentation poses a common concern among individuals with acne, especially those with darker skin tones, and it can endure for a prolonged period post-acne resolution. Laser therapies like Q-switched Nd:YAG (Neodymium-doped yttrium aluminum garnet) and fractional CO2 lasers have been identified as effective treatment options for post-acne hyperpigmentation. The study aims to compare the efficacy and side effects of Q-switched Nd:YAG laser and fractional CO2 laser in treating post-acne hyperpigmentation. It evaluates each laser individually and its relative performance. Material and Methods: A comparative prospective study was carried out at a tertiary care hospital in the southern region of India to evaluate the effectiveness of Q-switched Nd:YAG and fractional CO2 lasers in the treatment of post-acne hyperpigmentation. The study involved a total of 48 patients, with 3 lost to follow-up. Each participant received 4 sessions of Q-switched Nd:YAG laser on the left half of the face and 4 sessions of fractional CO2 laser on the right half of the face, with a 2-week interval between sessions. Assessment of results was conducted after 2 nd -week, 4 th -week, and 2-month post-final laser session using the physician’s global assessment and patient satisfaction score metrics, along with clinical photographs. Results: In a study comprising 45 participants, primarily females aged 20–40 years with skin type IV, Q-switched Nd:YAG laser, and fractional CO2 laser treatments were compared for post-acne hyperpigmentation. Results showed on the Q-switched Nd:YAG laser-treated left side, 60% had moderate to excellent improvement, with 80% satisfied to very satisfied. In contrast, the fractional CO2 laser-treated right side saw 40% with moderate improvement and 62.2% satisfied to very satisfied. Side effects such as erythema (22.2%) and edema (6.7%) were more prevalent with fractional CO2 laser compared to Q-switched Nd:YAG laser where there was only erythema (17.8%), no edema. Conclusion: Q-switched Nd:YAG laser shows superior efficacy and patient satisfaction compared to fractional CO2 laser in treating post-acne hyperpigmentation, making it a preferred choice due to its significant improvements and fewer adverse effects.