White spots on skin have several possible causes, ranging from harmless sun damage to autoimmune conditions like vitiligo. The most common culprits are a yeast overgrowth called tinea versicolor, sun-related aging spots, a childhood condition called pityriasis alba, and vitiligo. Figuring out which one you’re dealing with comes down to the size, location, and texture of the spots, plus your age and skin history.
Tinea Versicolor: A Common Fungal Overgrowth
Tinea versicolor is one of the most frequent causes of white patches, especially in warm, humid climates. It’s caused by Malassezia yeast, a type of fungus that naturally lives on everyone’s skin. Normally it causes no problems, but certain conditions trigger it to overgrow: high humidity, oily skin products, heavy sweating, or frequent use of steroid creams. When the yeast multiplies, sunlight stimulates it to produce a compound called azelaic acid, which bleaches the surrounding skin and creates lighter patches.
The spots tend to appear on the chest, back, and upper arms. They can look white, pink, or tan depending on your skin tone, and they often have a slightly scaly texture you can feel if you run a finger across them. A telltale sign is that the patches become more obvious after sun exposure, because the affected skin doesn’t tan like the surrounding areas. Under a Wood’s lamp (a type of UV light used in dermatology offices), tinea versicolor glows yellow-orange, which distinguishes it clearly from other causes.
Antifungal treatments, either topical or oral, clear the infection itself relatively quickly. But here’s what catches people off guard: the white spots can linger for weeks or even months after the fungus is gone, because the skin needs time to resume normal pigment production. The condition also tends to recur, particularly in summer months.
Vitiligo: When the Immune System Attacks Pigment Cells
Vitiligo affects roughly 0.5% to 2% of the global population, with prevalence highest in Europe (1.6%) and the US (1.4%). It happens when your immune system mistakenly identifies melanocytes, the cells that produce skin pigment, as threats and destroys them. The result is smooth, completely white patches that are sharply defined against the surrounding skin.
Unlike tinea versicolor, vitiligo patches have no scales or texture changes. The skin feels completely normal to the touch. Common locations include the hands, face, and areas around body openings like the eyes, nostrils, and mouth, though it can appear anywhere. Under a Wood’s lamp, vitiligo glows a striking bright white with sharp borders, making it easy for a dermatologist to confirm.
Two main triggers seem to set off or worsen vitiligo. Emotional or physical stress can alter how melanocytes function, and environmental factors like UV radiation or exposure to certain industrial chemicals can do the same. A family history of autoimmune conditions increases your risk. Vitiligo can start at any age, but most people notice it before age 30.
Treatment has improved significantly. A prescription cream that works by calming the immune response at the skin’s surface has shown meaningful results in clinical trials, with a significantly greater proportion of patients achieving at least 75% facial repigmentation compared to placebo at 24 weeks. Narrowband UV light therapy is another well-established option. Neither is a quick fix. Repigmentation happens gradually over months, and results vary by location on the body, with the face generally responding best.
Pityriasis Alba: White Patches in Children
If your child has pale, slightly rough patches on their cheeks, upper arms, or torso, pityriasis alba is the most likely explanation. It’s a common and harmless childhood skin condition that causes round or oval patches up to about an inch across. The patches often start as slightly pink or red spots, then fade to a color noticeably lighter than the surrounding skin. They may have a dry, lightly scaled texture and occasionally itch.
Pityriasis alba is strongly linked to atopic conditions. Children with eczema, asthma, or hay fever (or a family history of these) are more likely to develop it. The patches become more visible in summer when the surrounding skin tans but the affected areas don’t. This can alarm parents, but the condition resolves on its own over weeks to months. Keeping the skin moisturized helps with any dryness or flaking.
Sun Damage Spots After Age 40
Small, flat white spots that appear on the shins and forearms of adults over 40 are usually idiopathic guttate hypomelanosis, a long name for a simple problem: cumulative sun damage. Over decades, UV exposure gradually damages some melanocytes, causing them to produce less pigment in small, scattered areas.
These spots are typically smaller than a pea, though some can grow as large as a quarter. They’re perfectly round or oval, completely flat, and smooth. The most common locations are the forearms and shins, which makes sense since these areas receive the most incidental sun exposure over a lifetime. Less frequently, spots appear on the face, neck, or torso. They’re more noticeable on darker skin tones and become increasingly common with age. They’re purely cosmetic and don’t require treatment, though they don’t go away on their own either.
White Spots After Skin Inflammation
Several inflammatory skin conditions can leave behind lighter patches once the inflammation itself clears. This is called post-inflammatory hypopigmentation, and it’s temporary. The most common causes are eczema, psoriasis, and pityriasis alba. After treatment resolves the active rash or plaques, the affected skin may appear noticeably lighter than the surrounding area for a few weeks to several months before pigment production returns to normal.
This is especially common in people with medium to dark skin tones, where the contrast between normal and lighter skin is more visible. No special treatment is needed for the lighter patches themselves. The pigment gradually comes back as the melanocytes in the area resume normal function. Protecting the area from sun exposure helps prevent the contrast from becoming more pronounced while you wait.
Lichen Sclerosus: A Less Common Cause
Lichen sclerosus produces white, dry plaques that look and feel distinctly different from other causes. The affected skin becomes thin, wrinkled, and fragile, often described as resembling cigarette paper. Hair follicles in the area may appear raised and plugged with dry skin. The patches bruise or blister easily, sometimes without any noticeable injury.
While lichen sclerosus most commonly affects the genital area, it can also appear on the inner thighs, lower back, abdomen, under the breasts, neck, and shoulders. It’s a chronic condition that benefits from medical treatment, as untreated patches can cause scarring and skin thinning over time. If your white patches have that papery, fragile quality, it’s worth having a dermatologist take a look.
How to Tell the Difference
A few key details help narrow down what’s causing your white spots:
- Texture: Scaly or slightly rough patches point toward tinea versicolor or pityriasis alba. Completely smooth, normal-feeling skin suggests vitiligo or sun damage spots. Thin, papery skin suggests lichen sclerosus.
- Borders: Vitiligo has very sharp, well-defined edges. Tinea versicolor and pityriasis alba have softer, less distinct borders.
- Size and shape: Tiny round dots (pea-sized) on the shins and forearms are likely sun damage. Larger, irregular patches suggest vitiligo or tinea versicolor.
- Age: White patches on a child’s face are most likely pityriasis alba. New spots appearing after age 40 on the arms and legs are probably sun damage.
- Location: Chest and back suggest tinea versicolor. Hands, face, and around body openings suggest vitiligo. Shins and forearms in older adults suggest sun damage.
A dermatologist can confirm the diagnosis quickly, often just by examining the spots under a Wood’s lamp. Tinea versicolor, vitiligo, and several other conditions each produce a different color under UV light, making it a simple and painless way to get a definitive answer.