A person with hairy leukoplakia has a whitish, irregular coating on the sides of the tongue or lining of the mouth. By itself this condition is not contagious, but is most commonly associated with AIDS. Hairy leukoplakia has been linked to the Epstein-Barr virus in those with a poorly functioning immune system. Testing for HIV infection is important when confronted with this finding.

The lesions may appear smooth or flat, and are most often "hairy" or feathery in appearance.

Treatment usually includes the oral antiviral medication, acyclovir. Other options include valacyclovir and famciclovir.