What causes white patches on skin?

A patch may be lighter because the skin makes less melanin, because pigment-producing cells are absent from that area, or because fine scale reflects light from the surface. Hypopigmentation is a general description rather than one diagnosis. Pityriasis alba can leave pale, slightly dry patches, while tinea versicolor may cause lighter or darker areas with fine scale on the trunk. Vitiligo causes sharply defined areas of pigment loss and can affect skin, hair, or mucosal areas.

Other patterns include small sun-related pale spots, genital or body-area conditions such as lichen sclerosus, and colour change after inflammation or injury. Location, border, scale, itch, and whether the patches are increasing help guide an examination.

Take a clear photograph in natural light and note when the patches began, whether they itch or scale, and whether new areas are appearing. Use gentle, fragrance-free skincare and protect the lighter skin from sun exposure, which can make contrast more visible and leave it vulnerable to burning. Avoid steroid, antifungal, bleaching, or home remedies unless the diagnosis supports them. A clinician may inspect the surface, examine other body sites, or use a light examination to distinguish pigment loss from scale.

Arrange a dermatology assessment if patches are enlarging, sharply outlined, recurrent, scaly, itchy, painful, or located on the genitals. Seek prompt care for blistering, sores, bleeding, rapid inflammation, or signs of infection such as warmth, pus, and fever. Assessment is especially useful when white patches affect hair, eyes, mouth, or several body areas, or when the diagnosis is uncertain.

Ask whether the patch is truly lacking pigment or only covered by scale, which diagnoses fit its distribution, whether testing is needed, and how to protect or treat the affected skin.