Hairy leukoplakia is a white, slightly raised patch that forms on the tongue, caused by the Epstein-Barr virus (EBV) replicating in the surface cells of the mouth. It almost always appears on the sides of the tongue, and the patches cannot be scraped or wiped off. The condition is strongly linked to a weakened immune system, particularly HIV infection, and its appearance often signals that immunity has dropped significantly.
What It Looks Like
The hallmark of hairy leukoplakia is white or grayish-white patches on the lateral borders of the tongue. The patches are raised and thickened, with a corrugated or ridged texture that gives them a “hairy” appearance under close inspection. That texture comes from an overgrowth of the outer layer of skin cells on the tongue’s surface, driven by the virus disrupting how those cells normally mature and shed.
The patches are painless in most cases. They can be small and barely noticeable or cover a large portion of the tongue’s side. Unlike many other oral conditions, hairy leukoplakia rarely causes discomfort on its own, which means people sometimes have it for weeks or months before it gets noticed during a dental or medical exam.
How EBV Causes It
Most adults carry the Epstein-Barr virus. It’s the same virus responsible for mononucleosis, and after the initial infection it stays dormant in immune cells for life. In people with healthy immune systems, the virus remains dormant and causes no problems. But when immunity weakens, the virus can reactivate.
Here’s what happens in hairy leukoplakia: reactivated EBV particles infect the skin-like cells (keratinocytes) in the upper layers of the tongue’s surface. Normally, these cells are in the final stage of their life cycle and about to be shed. But EBV hijacks their programming, causing them to keep dividing when they should be dying off. The result is a buildup of abnormal, thickened tissue that forms the characteristic white patch. The virus actively replicates inside these cells and sheds infectious particles into saliva.
A key detail is that EBV doesn’t just arrive at the tongue directly. The virus reactivates in immune cells called B lymphocytes, which release new viral particles. Those particles then make their way into the oral tissue through immune cells that migrate into the tongue’s surface layer. Once there, EBV exploits a reduction in the local immune defenses, specifically a drop in specialized immune cells called Langerhans cells, to establish itself and replicate freely.
Who Gets It
Hairy leukoplakia is most closely associated with HIV. In studies of people living with HIV, roughly 10% develop it, and its appearance correlates with a CD4 count below 200 cells per milliliter. That’s the same threshold used to define AIDS, so hairy leukoplakia often serves as a visible clinical marker of severe immune suppression. In fact, it was first described in 1984, early in the AIDS epidemic, when clinicians noticed this distinctive tongue lesion appearing in their patients.
HIV isn’t the only cause. Anyone with a significantly weakened immune system can develop hairy leukoplakia. This includes people taking immunosuppressive medications after organ transplants, those undergoing chemotherapy, and people on long-term corticosteroid therapy. In rare cases, it has been reported in people with no known immune deficiency, though this is uncommon enough that its appearance in an otherwise healthy person typically prompts testing for underlying conditions, including HIV.
Hairy Leukoplakia vs. Oral Thrush
The most common mix-up is with oral thrush (candidiasis), which also produces white patches in the mouth. The key difference is simple: thrush patches can be wiped or scraped away, leaving a red or raw surface underneath. Hairy leukoplakia patches cannot be removed by scraping. They’re part of the tongue’s surface tissue itself, not a coating sitting on top of it.
Location also helps distinguish them. Hairy leukoplakia strongly favors the sides of the tongue. Thrush tends to appear more broadly, on the inner cheeks, roof of the mouth, gums, and tongue surface. Both conditions can occur simultaneously in immunocompromised people, which sometimes complicates identification. A biopsy can confirm the diagnosis when there’s uncertainty. Under a microscope, hairy leukoplakia shows a distinctive pattern: a thick outer layer of abnormal skin cells with characteristic balloon-shaped cells just below the surface, each surrounded by a clear halo.
What It Means for Your Health
Hairy leukoplakia itself is not cancerous and does not become cancerous. It’s benign. But its significance lies in what it reveals about the immune system. For someone who hasn’t been tested for HIV, the appearance of hairy leukoplakia is a strong signal to get tested. For someone already living with HIV, it typically indicates that the virus is not well controlled and that immune function has declined to a concerning level.
The onset of hairy leukoplakia tracks with a sustained drop in CD4 cells combined with a sharp rise in viral load. This makes it a useful clinical indicator, sometimes appearing before blood work reveals how far immune suppression has progressed.
Treatment and Outlook
In many cases, hairy leukoplakia doesn’t require direct treatment. The patches are painless and pose no danger on their own. The priority is addressing the underlying immune suppression. For people with HIV, starting or adjusting antiretroviral therapy to bring the virus under control and rebuild CD4 counts often causes hairy leukoplakia to resolve on its own.
When treatment of the patches themselves is desired, antiviral medications that target EBV replication can shrink or eliminate them. However, the patches frequently return once antiviral treatment stops, because the underlying EBV infection is lifelong and will reactivate again if immune function remains low. This is why managing the root cause of immunosuppression matters more than treating the tongue lesion directly.
For transplant recipients or others on immunosuppressive drugs, treatment decisions are more nuanced since the medications suppressing their immune systems can’t simply be stopped. In these cases, antiviral therapy for the patches may be used as a longer-term management strategy, or the patches may simply be monitored if they’re not causing symptoms.