A hairy tongue is caused by an overgrowth of the hair-like rough surface of the tongue (papillae). The tongue will look like it is covered with hair.

A person with a hairy tongue often has severe bad breath (halitosis). Soreness is not usually present.

Causes of a hairy tongue include poor oral hygiene, decreased saliva in the mouth, and side effects of antibiotic treatment. Hairy tongue can also be caused by the overuse of some types of mouthwashes and by smoking or the use of smokeless (spit) tobacco.

Hairy tongue is not a serious condition and will usually clear up after the antibiotic or mouthwash is discontinued, saliva flow increases, or oral hygiene improves. Brushing the tongue daily with a soft-bristled toothbrush and toothpaste or a solution of 1 part hydrogen peroxide to 2 parts water may help remove the hair-like growths. This may also help prevent hairy tongue.