White spots on your skin usually come from one of a handful of common conditions, most of them harmless. The cause depends on the size of the spots, where they appear, and whether they’re spreading. A small fungal overgrowth, sun damage over time, dry skin patches, or an autoimmune condition can all leave lighter areas on your skin. Here’s how to tell what you’re likely dealing with.
Tinea Versicolor: A Fungal Overgrowth
The most common cause of white spots, especially on the chest, back, and upper arms, is tinea versicolor. A type of yeast called Malassezia lives naturally on everyone’s skin. When it overgrows, it interferes with your skin’s normal pigment production, creating uneven patches that look lighter (or sometimes darker) than surrounding skin. The spots are usually flat, slightly scaly, and may merge together into larger areas.
Tinea versicolor tends to flare in warm, humid weather or after heavy sweating. It’s not contagious, and it’s not a sign of poor hygiene. The yeast simply thrives when conditions on your skin shift in its favor. Under a UV lamp in a doctor’s office, tinea versicolor patches glow orange, which makes it easy to confirm. Antifungal creams or shampoos clear the infection, but the white spots themselves can take weeks or months to return to your normal skin color even after the fungus is gone.
Sun Damage Spots That Appear With Age
If you’re noticing small, round white dots on your shins, forearms, or other sun-exposed areas, these are likely idiopathic guttate hypomelanosis. They’re tiny, typically 2 to 6 millimeters across, and scattered rather than clustered. They look like confetti-sized drops of lost color.
These spots result from years of cumulative sun exposure gradually wearing down the pigment-producing cells in those areas. They become increasingly common as you age: a recent study found that 87% of people aged 40 and older had at least one of these spots, and up to 80% of people over 70 are affected. They can appear as early as your 20s or 30s, though. The spots are completely harmless and don’t spread to other people, but they’re permanent. Sun protection slows the development of new ones.
Pityriasis Alba: Pale Patches in Children
If a child has round or oval whitish patches on their cheeks, upper arms, or neck, pityriasis alba is the likely explanation. The patches are slightly dry and faintly scaly, with blurred edges rather than sharp borders. This condition is considered a mild form of eczema and is most common in children who have a history of dry or sensitive skin.
Pityriasis alba tends to be more noticeable in summer, when surrounding skin tans but the affected patches don’t. In winter, dry indoor air can worsen the scaling. The patches aren’t dangerous and typically fade on their own over months to a couple of years. Keeping the skin well moisturized helps them look less obvious in the meantime.
Vitiligo: When the Immune System Targets Pigment Cells
Vitiligo produces smooth, completely white patches where the skin has lost all its pigment. Unlike the faint, slightly off-color spots from other causes, vitiligo patches are strikingly white with well-defined edges. They commonly appear on the hands, face, around the eyes and mouth, and on the elbows, knees, or genitals, though they can develop anywhere.
The underlying cause is autoimmune. Your immune system’s T cells mistakenly attack and destroy melanocytes, the cells responsible for producing skin pigment. This also damages the stem cells that would normally regenerate new melanocytes, which is why the color loss can be permanent without treatment. Globally, vitiligo affects roughly 0.36% of the general population, translating to about 28.5 million people worldwide. It’s more prevalent in central Europe and south Asia, where rates reach roughly 0.52%.
For years, no approved treatment existed specifically for repigmentation. That changed with the approval of a topical cream (ruxolitinib) that works by blocking the immune signals driving melanocyte destruction. In clinical trials, about 50% of patients using this cream achieved significant facial repigmentation by one year of use. The treatment works best on the face and is less effective on hands and feet, where blood flow and skin biology differ. Phototherapy, which uses targeted UV light to stimulate pigment cells, remains another common option and is often combined with topical treatments.
Post-Inflammatory Hypopigmentation
If a white spot appeared where you previously had a burn, a rash, a bad pimple, or any kind of skin inflammation, the pigment loss is a direct aftermath of that injury. Burns, eczema flares, psoriasis patches, certain laser treatments, and even insect bites can temporarily damage the pigment-producing cells in the affected area. The result is a lighter patch that matches the exact shape of the original wound or rash.
Most cases of post-inflammatory hypopigmentation resolve on their own as the pigment cells recover. The timeline varies widely depending on your skin tone and the severity of the original inflammation. Darker skin tones tend to show these spots more prominently and may take longer to even out. There’s no reliable way to speed up the process, but protecting the area from further sun damage helps prevent the contrast between the light patch and surrounding skin from becoming more obvious.
Lichen Sclerosus: White Patches With Texture Changes
Lichen sclerosus is less common but worth knowing about, particularly if you notice white patches in the genital or anal area. Unlike the conditions above, lichen sclerosus changes the texture of your skin, not just the color. Affected skin becomes thin, wrinkled, fragile, and sometimes shiny or smooth in an unusual way. It can also appear on the back, shoulders, upper arms, and breasts.
This condition can cause itching, discomfort, and, in the genital area, pain during sex or urination. It requires treatment because untreated lichen sclerosus can cause scarring and, in rare cases, slightly increases the risk of skin cancer in the affected area. A doctor can usually diagnose it by appearance and may take a small biopsy to confirm.
Nutritional Deficiencies and White Spots
Vitamin B12 deficiency has a documented link to skin color changes, including vitiligo. In one case series of 63 patients with B12 deficiency, 3% developed vitiligo and 19% developed other pigment changes. The connection isn’t fully understood, but B12 plays a role in melanin production, and correcting the deficiency sometimes helps restore pigment. If your white spots are accompanied by fatigue, tingling in your hands or feet, or mouth sores, a B12 deficiency is worth investigating with a simple blood test.
How to Tell Which One You Have
A few features help narrow things down quickly:
- Size and shape: Tiny dots (2 to 6 mm) scattered on sun-exposed limbs point to sun damage spots. Larger, irregular patches suggest tinea versicolor, vitiligo, or pityriasis alba.
- Texture: Slight scaliness suggests tinea versicolor or pityriasis alba. Completely smooth, stark-white patches point to vitiligo. Thin, wrinkled skin suggests lichen sclerosus.
- Location: Chest and back are classic for tinea versicolor. Face and hands for vitiligo. Cheeks and arms in a child for pityriasis alba. Genital area for lichen sclerosus.
- Color contrast: Faintly lighter than your normal skin tone is typical of tinea versicolor and pityriasis alba. Completely white, like paper, is characteristic of vitiligo.
A dermatologist can usually identify the cause on sight. When it’s not obvious, a UV lamp exam takes seconds and distinguishes between fungal causes and autoimmune pigment loss. Tinea versicolor glows orange under the lamp, while vitiligo patches appear bright white with crisp borders.