Pityriasis alba is a common, harmless skin condition that causes pale, slightly scaly patches, most often on the face, arms, and upper body. It primarily affects children between the ages of 3 and 16, though it can occasionally appear in young adults. The patches are not contagious, not caused by infection, and almost always resolve on their own over months to years without leaving any permanent change in skin color.
What Pityriasis Alba Looks Like
The hallmark of pityriasis alba is round or oval patches of lighter skin, typically 1 to 4 centimeters across, though they can sometimes be larger. The patches usually have slightly blurry, irregular edges rather than sharp borders. A fine, dry scale often covers the surface, which is where the name comes from: “pityriasis” refers to scaling, and “alba” means white.
The cheeks are the single most common location, but patches also appear on the upper arms, neck, shoulders, and trunk. Most children develop somewhere between 1 and 20 patches at a time. The lighter color becomes especially noticeable in summer, when surrounding skin tans and the affected areas do not. In darker skin tones, the contrast can be quite striking, which is often what prompts a parent to seek medical advice.
How the Patches Develop Over Time
Pityriasis alba typically moves through three stages, though the first stage is so subtle that many people never notice it. Initially, the patches may appear slightly pink or red with mild scaling. This early inflammatory phase is brief and usually painless, though the skin can feel mildly rough or dry.
The pink color then fades, leaving behind the characteristic pale, hypopigmented patch. This is the stage most people first notice. The patches are not completely white, as they still retain some pigment. Over time, the scaling diminishes and the color difference gradually becomes less obvious as pigment slowly returns. Full resolution typically takes several months to a few years. Most cases clear entirely by early adulthood.
What Causes It
The exact cause of pityriasis alba is not fully understood, but it is closely linked to atopic dermatitis (eczema). Many children with pityriasis alba either have eczema, have a history of it, or have family members with eczema, asthma, or allergies. Not every child with pityriasis alba has eczema, but the two conditions share a tendency toward dry, easily irritated skin.
At the cellular level, the condition involves a mild disruption of pigment production in the affected skin. Histologic studies show irregular distribution of melanin in the base layer of the epidermis, along with changes around hair follicles including plugging and mild inflammation. The pigment-producing cells are still present and functional, which is why the patches eventually regain their normal color. Sun exposure, wind, dry air, and frequent bathing without moisturizing can all worsen the dryness that makes the patches more visible.
Pityriasis Alba vs. Vitiligo
The condition parents worry about most when they see pale patches on a child’s skin is vitiligo, which causes permanent loss of pigment. The two look different in important ways. Vitiligo patches are completely white, not just lighter than surrounding skin, and they have sharply defined borders. Vitiligo also tends to favor the skin around the eyes, mouth, hands, and genitals.
Under a Wood’s lamp (a handheld ultraviolet light used in dermatology offices), the distinction becomes even clearer. Vitiligo patches fluoresce bright white with crisp edges because the pigment-producing cells are entirely absent. Pityriasis alba patches become more visible under the lamp but do not fluoresce, and their borders remain soft and indistinct. This simple, painless exam is often all that’s needed to tell the two apart.
Ruling Out Fungal Infections
Another condition that can look similar is tinea versicolor, a superficial fungal infection that also creates lighter (or sometimes darker) patches on the skin. Tinea versicolor tends to affect the upper back, chest, and shoulders, more commonly in adolescents and young adults. The patches often have a slightly different texture and may be itchy.
If there’s any doubt, a simple skin scraping examined under a microscope with a potassium hydroxide solution will reveal fungal elements if tinea versicolor is the cause. Pityriasis alba shows no fungal organisms on this test. In most cases, though, a dermatologist can distinguish the two just by appearance and location.
Managing the Patches
Because pityriasis alba resolves on its own, treatment focuses on reducing dryness and minimizing the cosmetic appearance of the patches rather than curing the condition. The single most effective step is consistent use of a thick, fragrance-free moisturizer. Applying it at least twice daily, especially after bathing, helps restore the skin barrier and can reduce the visible scaling that makes patches stand out.
Sun protection also plays a practical role. Sunscreen on the face and exposed areas prevents surrounding skin from tanning further, which reduces the contrast between affected and unaffected skin. This won’t speed up repigmentation, but it makes the patches far less noticeable during summer months.
For patches that are particularly dry, rough, or mildly inflamed, a low-strength topical anti-inflammatory cream prescribed by a dermatologist can help settle the irritation and may modestly speed the return of pigment. Non-steroidal options that calm the immune response in the skin are sometimes preferred for the face, since they can be used for longer periods without thinning the skin. In most cases, though, moisturizer and sun protection are enough.
Who Gets It and How Long It Lasts
Pityriasis alba is one of the most common skin conditions in childhood, affecting an estimated 2 to 5 percent of children worldwide. It occurs across all skin types but is diagnosed more frequently in children with darker complexions, largely because the contrast makes it more noticeable rather than because it is genuinely more common in those populations. Boys and girls are affected at roughly equal rates.
The condition tends to recur over several years, especially in children with underlying eczema or very dry skin. New patches may appear as old ones fade. Most children outgrow pityriasis alba entirely by their late teens. The patches do not scar, and once the pigment returns, the skin looks completely normal. In rare cases, a more extensive variant can develop with widespread patches on the trunk and limbs, but even this form is benign and self-limiting.