White spots on the skin (called hypopigmentation or depigmentation ) appear when there is a decrease or loss of melanin, the natural pigment that gives color to the skin, hair and eyes.
They can have many causes, ranging from benign and temporary problems to chronic or autoimmune conditions. Most are not serious, but some require medical evaluation to confirm the diagnosis and rule out potential complications.
Main causes of white spots on the skin
Here are the most common ones, classified according to age and skin type:
1. Idiopathic guttate hypomelanosis (sun spots or “small white drops”)
Very common after age 40–50, especially in people with fair skin.
Small, round, white spots (2–6 mm) appear on the arms, legs, back, and hands.
Cause: cumulative sun exposure + natural aging (melanocytes function less in exposed areas).
They are not itchy or painful; harmless but generally irreversible.
2. Pityriasis versicolor (or tinea versicolor)
A fungal infection caused by yeasts of the genus Malassezia (normally present on the skin but which proliferate in warm, sweaty, and humid conditions).
It causes white, pink, or light brown spots on the chest, back, neck, and arms. These spots
are more noticeable after sun exposure (the fungus disrupts even pigmentation).
It may also cause mild itching or fine peeling.
3. Pityriasis alba
A mild form of atopic dermatitis (eczema). It presents as
dry, slightly scaly, round or oval white patches, primarily on the face (cheeks), neck, and arms.
Very common in children and adolescents, but also possible in adults with atopic dermatitis.
It is associated with dry skin, sun exposure, and allergies.
