The skin condition most commonly associated with losing pigment is vitiligo, an autoimmune disorder that causes white patches to appear on the skin. It affects roughly 1% of the global population and can develop at any age, though it most often appears before age 30. While vitiligo is the most well-known cause of pigment loss, a few other conditions can look similar, so understanding the differences matters.
Why Vitiligo Causes White Patches
Your skin gets its color from specialized cells called melanocytes, which produce the pigment melanin. In vitiligo, the immune system mistakenly attacks and destroys these melanocytes. The process starts when melanocytes become stressed and release certain proteins that act as alarm signals. The immune system interprets those signals as a threat and sends a type of white blood cell to destroy the melanocytes. Those immune cells then release chemical messengers that recruit even more immune cells to the area, creating a cycle of destruction that spreads the pigment loss outward.
This is why vitiligo patches tend to grow over time. It’s not an infection, it’s not contagious, and it’s not caused by anything you did. It’s a misdirected immune response, similar in mechanism to other autoimmune conditions like type 1 diabetes or thyroid disease.
What Vitiligo Looks Like
Vitiligo appears as smooth, flat patches of skin that have lost their color completely. On lighter skin, the patches may be subtle until sun exposure tans the surrounding skin and creates contrast. On darker skin tones, the patches are often more noticeable year-round. The patches have no texture change: they’re not scaly, raised, or rough. They’re simply white.
The most common form, called non-segmental vitiligo, tends to appear symmetrically on both sides of the body. If a patch develops on your left hand, a similar patch often shows up on your right hand. It frequently affects the face, hands, wrists, elbows, knees, feet, and areas around body openings like the eyes, nostrils, and mouth. The hair within affected patches usually keeps its color early on, though it can turn white as the condition progresses.
A less common form, segmental vitiligo, behaves differently. It appears on only one side of the body, spreads rapidly within a limited area over 6 to 24 months, and then typically stops. Up to 50% of people with segmental vitiligo develop white hairs in the affected area early in the course of the condition.
What Triggers New Patches
People with vitiligo are susceptible to something called the Koebner phenomenon, where new patches of pigment loss develop at sites of skin injury. Cuts, scrapes, burns, friction from tight clothing, tattoos, and even sunburn can trigger new white patches on previously unaffected skin. Studies estimate this happens in 21 to 62% of vitiligo patients, and its presence tends to correlate with more active disease and a lower response to treatment.
Emotional stress is another commonly reported trigger, though its role is harder to quantify. Many people notice their first patches or a flare of existing patches during periods of significant psychological stress. Hormonal changes, including pregnancy and thyroid fluctuations, have also been linked to new activity.
How Doctors Confirm the Diagnosis
A dermatologist can often diagnose vitiligo just by looking at the skin, but a Wood’s lamp exam makes it definitive. This handheld device emits ultraviolet light that causes depigmented skin to glow bright white, making patches visible even on very fair skin where they might otherwise blend in. The exam also helps distinguish vitiligo from other conditions that cause lighter (but not completely white) patches.
Because vitiligo is linked to other autoimmune conditions, your doctor will likely order blood work to check your thyroid function. About 14.3% of vitiligo patients have an autoimmune thyroid disorder such as Hashimoto’s thyroiditis or Graves’ disease, and roughly 21% test positive for thyroid antibodies even without symptoms yet. The risk of thyroid problems increases with age, so periodic monitoring is worthwhile.
Treatment and Repigmentation
Vitiligo treatment focuses on encouraging melanocytes to repopulate the white patches, a process called repigmentation. The most established option is narrowband UVB phototherapy, which involves standing in a light booth two to three times per week. After about four months of consistent treatment, roughly 67% of patients see some repigmentation. More significant results, with 75% or greater repigmentation, have been reported in 63% of patients who continue treatment for a full 12 months. The average course involves around 45 sessions. Repigmentation typically starts as small dots of color appearing within the white patches, gradually expanding and merging.
In 2022, the FDA approved a topical cream containing a JAK inhibitor (sold as Opzelura) for non-segmental vitiligo in patients 12 and older. This is the first FDA-approved medication specifically targeting repigmentation. In clinical trials, 30% of patients using the cream achieved at least 75% improvement in facial vitiligo scores after 24 weeks, compared to 10% using a placebo. The cream works by blocking the chemical signaling pathway that drives the immune attack on melanocytes.
Other options include topical corticosteroids and calcineurin inhibitors, which suppress local immune activity. For stable vitiligo that hasn’t spread in a year or more, surgical approaches like melanocyte transplantation can move pigment-producing cells from unaffected skin into white patches. Results vary depending on the location and size of the patches, with the face and neck generally responding best to treatment and the hands and feet responding least.
Other Conditions That Cause Lighter Skin
Not every light patch on the skin is vitiligo. Several other conditions can look similar at first glance but have different causes and outcomes.
- Pityriasis alba causes light-colored, slightly scaly patches, most often on the face and upper arms of children and teenagers. The patches are lighter than surrounding skin but not completely white. It’s harmless and usually resolves on its own.
- Tinea versicolor is a fungal infection that creates patches of discolored skin with a fine, dry, scaly texture. The patches can be lighter or darker than surrounding skin and are most common on the trunk and shoulders. Antifungal treatments clear it up, though the color difference can take weeks to even out.
- Post-inflammatory hypopigmentation occurs after skin injuries, acne, eczema, or burns heal. The affected area loses some pigment temporarily. Unlike vitiligo, the color usually returns over months.
- Albinism is a genetic condition present from birth that affects pigment production throughout the entire body, including the skin, hair, and eyes. It’s not an acquired condition like vitiligo.
The key distinction is that vitiligo produces completely depigmented (milk-white) patches, while most other conditions produce patches that are lighter than normal but still retain some color. A Wood’s lamp exam easily separates the two.