Why Is Ultraviolet Radiation the Primary Cause of Melasma?

Under normal circumstances, ultraviolet (UV) radiation directly stimulates melanocytes—pigment-producing cells located in the basal layer of the skin—causing them to become hyperactive and proliferate rapidly. This accelerates melanin synthesis and accumulation, ultimately leading to melasma.

Upon excessive UV exposure, the epidermal barrier sustains mild damage, resulting in diminished skin metabolic capacity. Consequently, newly synthesized melanin cannot be properly metabolized and eliminated, leading to its persistent deposition between the epidermis and the superficial dermis. With prolonged UV exposure, melanin accumulates progressively in uneven layers, gradually forming patchy, yellowish-brown pigmented lesions—i.e., melasma. Moreover, UV radiation perpetuates cutaneous inflammatory responses and disrupts the rhythmic regulation of pigment metabolism, thereby deepening the color and enlarging the area of existing pigmented spots. This is the primary underlying cause of melasma recurrence and resistance to fading.

In daily skincare, comprehensive sun protection throughout the day is essential. When outdoors, wear sun-protective hats and carry umbrellas to avoid direct exposure to intense sunlight. Simultaneously, adhere to a gentle skincare regimen to repair and reinforce the skin barrier, maintain overall skin stability, and minimize abnormal melanin accumulation.