White Patches on Skin: Causes and Treatment

Hypopigmentation vs depigmentation

• Hypopigmentation: reduced pigment, so the skin is lighter than normal but not completely white. Examples: tinea versicolor, pityriasis alba, post-inflammatory hypopigmentation.
• Depigmentation: complete loss of pigment, leaving milk-white or chalk-white skin. Example: vitiligo.

A doctor can tell them apart using a Wood's lamp (ultraviolet light), under which depigmented patches glow bright white.

Common causes of white patches

Tinea versicolor

Tinea versicolor (pityriasis versicolor) is caused by overgrowth of Malassezia, a yeast that normally lives on the skin. It produces small, round, pale, pink or light brown patches with fine scale, mainly on the chest, back, neck and upper arms. Patches become more obvious after a tan, because the yeast stops the skin tanning normally. It is common in teenagers and young adults, in hot, humid weather and with sweating. It is not contagious.

Pityriasis alba

A mild form of eczema in children and teenagers, especially those with darker skin or atopic dermatitis. It causes faint, pale, slightly dry and scaly patches, usually on the face and upper arms, more visible in summer. It fades over months to years and needs only moisturizer, sun protection and sometimes a mild steroid cream.

Vitiligo

Vitiligo is an autoimmune condition in which the immune system destroys pigment cells. It causes sharply defined, milk-white patches, often symmetrical, around the eyes, mouth, hands, feet, elbows, knees and genitals. Hair in the patches may turn white. It affects about 1% of people, often starts before age 30, and is linked to thyroid disease and other autoimmune conditions. It is not contagious.

Post-inflammatory hypopigmentation

Skin can lose pigment after eczema, psoriasis, burns, blisters, infections, chemical peels or laser treatment. The patches match the shape of the original problem and usually repigment over months. See post-inflammatory hypopigmentation.

Idiopathic guttate hypomelanosis

Small, flat, white spots 2 to 5 mm across on the shins and forearms in people over 40, caused by cumulative sun exposure. Harmless but permanent.

Less common causes

• Lichen sclerosus: white, thin, wrinkled, itchy skin, most often on the vulva or penis. It can scar and carries a small risk of skin cancer, so it needs treatment and follow-up.
• Morphea: a localized form of scleroderma with hard, shiny, ivory patches surrounded by a purple ring.
• Nevus depigmentosus: a stable white birthmark present from early childhood.
• Halo nevus: a white ring around a mole, common in teenagers.
• Tuberous sclerosis: white "ash-leaf" patches present from birth, with seizures or developmental problems.
• Leprosy: pale, numb patches; rare in the US but still seen in some parts of the world.
• Albinism: a genetic lack of pigment affecting all of the skin, hair and eyes.
• Chemical leukoderma: depigmentation after contact with certain chemicals, such as some hair dyes and rubber products.

Telling the causes apart

How a doctor diagnoses white patches

The doctor will look at the color, edges, scale and distribution of the patches, ask when they appeared and about rashes, sun exposure and family history, and may use a Wood's lamp. A skin scraping viewed under the microscope confirms tinea versicolor. A small biopsy is used for uncertain cases or lichen sclerosus. Blood tests for thyroid disease are often done in vitiligo.

Treatment

• Tinea versicolor: antifungal shampoos (selenium sulfide or ketoconazole) applied to the skin, antifungal creams, or antifungal tablets for widespread cases. The color takes weeks to months to return after the yeast is cleared, and the infection often recurs in summer, so preventive washes help.
• Pityriasis alba: moisturizers, sunscreen and occasionally a mild steroid cream.
• Vitiligo: steroid creams, calcineurin inhibitor creams (tacrolimus, pimecrolimus), ruxolitinib cream, and narrowband UVB phototherapy. Cosmetic camouflage is an option. Response is best on the face; hands and feet respond less.
• Lichen sclerosus: strong steroid ointment and regular follow-up.
• Sun protection for all types: pale patches burn easily, and tanning of surrounding skin makes them more noticeable.

Frequently asked questions

What causes white patches on the skin?

The most common causes are tinea versicolor (a yeast overgrowth), pityriasis alba (a mild eczema in children), vitiligo (autoimmune pigment loss), pale patches after skin inflammation, and small white sun spots in older adults. Less often, lichen sclerosus, morphea or genetic conditions are responsible.

Are white patches on the skin a sign of a vitamin deficiency?

Rarely. White patches are not typically caused by vitamin deficiency, though low vitamin B12 and some other deficiencies have been loosely linked with vitiligo or pale skin. Most white patches have a skin cause, such as a yeast infection, eczema or vitiligo, which a doctor can diagnose.

How can I tell if white patches are vitiligo or a fungal infection?

Fungal patches (tinea versicolor) are slightly scaly, not completely white, and usually on the chest and back. Vitiligo patches are smooth, chalk-white with sharp edges, and often around the eyes, mouth, hands and joints. A Wood's lamp or skin scraping confirms the diagnosis.

Are white patches on the skin contagious?

No. Vitiligo, pityriasis alba and post-inflammatory hypopigmentation are not contagious. Tinea versicolor is caused by a yeast that already lives on everyone's skin, so it does not spread from person to person in any meaningful way.