Vitiligo develops when the cells that produce skin pigment, called melanocytes, are destroyed or stop functioning. In most cases, your own immune system is responsible for attacking these cells. About 0.4% of the global population has vitiligo, with prevalence roughly equal between men and women, and it can appear at any age, though adults are more commonly affected than children.
There is no single cause. Vitiligo results from a combination of genetic vulnerability, immune system malfunction, and environmental or physical triggers that set the process in motion.
The Immune System Attacks Pigment Cells
The most common form of vitiligo, called non-segmental vitiligo, is an autoimmune condition. Your immune system mistakes melanocytes for threats and sends specialized killer T cells to destroy them. Research on skin biopsies from people with vitiligo has shown that T cells at the edges of white patches are specifically primed to recognize and attack melanocyte proteins. These T cells can infiltrate normally pigmented skin and efficiently kill melanocytes within that environment, which is why patches tend to grow outward over time.
This autoimmune process explains why vitiligo often appears alongside other autoimmune conditions. People with vitiligo have a higher risk of autoimmune thyroid disease, alopecia areata (patchy hair loss), and pernicious anemia. If you already have one autoimmune condition, or if autoimmune diseases run in your family, your risk of developing vitiligo increases.
Genetics Play a Significant Role
Vitiligo runs in families. Having a close relative with the condition raises your risk, though most people with vitiligo have no family history at all. Researchers have identified susceptibility genes on multiple chromosomes that influence how the immune system behaves and how melanocytes respond to stress. Many of these genes overlap with those linked to other autoimmune diseases, which helps explain why vitiligo clusters with conditions like thyroid disorders.
Genetics alone don’t cause vitiligo. They create vulnerability. Something else, whether it’s stress, a sunburn, or chemical exposure, typically acts as the spark.
Oxidative Stress Damages Melanocytes From Within
Melanocytes in people with vitiligo accumulate abnormally high levels of hydrogen peroxide, a reactive molecule that damages cells from the inside. Healthy skin produces hydrogen peroxide naturally but breaks it down with protective enzymes. In vitiligo, this cleanup system fails, and hydrogen peroxide builds up to concentrations high enough to disable several critical processes.
The excess hydrogen peroxide damages enzymes that melanocytes need to produce pigment. It also oxidizes signaling molecules that normally promote melanin production, rendering them nonfunctional. This creates a vicious cycle: melanocytes become increasingly stressed and dysfunctional, which may make them more visible to the immune system as targets.
Physical Triggers That Can Start New Patches
If you already have vitiligo or a genetic predisposition to it, physical injury to the skin can trigger new white patches at the injury site. This is called the Koebner phenomenon, and it can happen after cuts, burns, sunburns, tattoos, piercings, surgical wounds, insect bites, or even scratching. Any injury that penetrates through the top and middle layers of skin can potentially set it off.
New patches from the Koebner phenomenon typically appear weeks after the injury, not immediately. They look identical to existing vitiligo patches. This is one reason dermatologists often advise people with active vitiligo to protect their skin from unnecessary trauma and severe sun exposure.
Emotional Stress and Hormonal Changes
Many people report that their vitiligo first appeared or worsened during a period of intense emotional stress. This isn’t coincidental. Stress triggers the release of catecholamines, the same family of chemicals that includes adrenaline and dopamine. People with both stable and active vitiligo show significantly elevated levels of these stress chemicals compared to people without the condition.
Dopamine is particularly relevant. It’s a potent source of oxidative stress and can directly trigger cell death in melanocytes. When stress hormones flood the system, the byproducts of their breakdown generate reactive molecules that may damage pigment cells in the early phases of the disease. Hormonal shifts during puberty, pregnancy, or childbirth can also act as triggers, likely through similar pathways.
Chemical Exposure in the Workplace
Certain industrial chemicals can destroy melanocytes on contact, producing white patches that look identical to vitiligo. Phenolic compounds are the most well-documented culprits. Workers in rubber manufacturing, for example, have developed depigmentation after handling materials containing compounds like para-tert-butylphenol, a known depigmenting agent that was present as an unintended byproduct in commercial rubber stock. Hair dyes, adhesives, and cleaning agents containing phenol-based chemicals have also been linked to occupational vitiligo.
Chemical-induced vitiligo can be tricky because the offending substance isn’t always listed on a product label. In documented workplace outbreaks, the depigmenting chemicals were byproducts of manufacturing, not intentional ingredients.
A Less Common Type With a Different Cause
Segmental vitiligo accounts for a smaller proportion of cases and behaves differently. Rather than spreading symmetrically across both sides of the body, it affects one area, often following the distribution pattern of a single nerve. The NHS describes it as being caused by chemicals released from nerve endings in the skin that are toxic to melanocytes. Segmental vitiligo tends to start earlier in life, progress for a limited period, and then stabilize, unlike non-segmental vitiligo, which can continue spreading for years.
Because segmental vitiligo appears to be driven by the nervous system rather than the immune system, it doesn’t carry the same association with other autoimmune diseases and responds differently to treatment.
Who Is Most at Risk
Your risk of developing vitiligo is higher if you have a family history of vitiligo or other autoimmune conditions, if you already have an autoimmune disease like thyroid disorder or type 1 diabetes, or if you have certain types of cancer, including melanoma or non-Hodgkin lymphoma. Specific gene variants increase susceptibility, but no genetic test can predict whether you’ll develop the condition.
Vitiligo affects all skin tones equally, though it’s more visually apparent on darker skin. The global prevalence in children and adolescents is about 0.27%, rising to 0.70% in adults, suggesting that cumulative exposure to triggers over a lifetime plays a role in who ultimately develops visible disease.