Post-acne Hyperpigmentation

The goal of this clinical trial is to evaluate the efficacy and safety of a combination serum containing Melasyl™, 10% Niacinamide, Hyaluronic Acid, and HEPES when used as a moisturizer after QS-Nd:YAG 1064 nm low-fluence laser treatment for melasma and post-acne hyperpigmentation. The study aims to answer the following main questions: * Does the combination serum reduce hyperpigmented lesions after laser treatment for melasma and post-acne hyperpigmentation? * Does the serum improve skin hydration following laser therapy for melasma? * Is the combination serum safe for use after laser treatment, without causing irritation or adverse effects? Participants will be female patients aged 18-60 years, clinically diagnosed with melasma or post-acne hyperpigmentation (skin types IV and V), who visit the Dermatology \& Venereology Outpatient Clinic for QS-Nd:YAG 1064 low-fluence laser treatment. All participants will have undergone a 2-week priming period using either 2% hydroquinone cream or the test serum prior to laser treatment. Written informed consent is required. Participants will be randomly assigned to receive either the test serum or 2% hydroquinone cream based on a coded allocation. The product will be applied twice daily after facial cleansing, and sunscreen will be used 15 minutes before outdoor activities. Treatment lasts for 2 weeks, with participants recording application times and any adverse effects in a diary. Evaluations-including facial photography, mMASI, mexameter, dermoscopy, Wood's lamp, and PAHPI-will be conducted at baseline and at 1, 2, and 4 weeks post-laser. Erythema and subjective assessment (VAS) will be performed 15 minutes after the laser procedure.