A man's tongue turned green and hairy after he took antibiotics

• A man went to the doctor with a green, hair-like coating on his tongue.
• He had taken antibiotics around 21 days before seeking medical help.

A man's tongue turned green and hairy after he took antibiotics, according to a case report.

The unnamed 64-year-old man from Ohio, who was a smoker, told doctors his tongue had been discolored for two weeks, doctors wrote in the New England Journal of Medicine.

The man had completed a course of antibiotics around 21 days before he visited the doctor.

He was diagnosed with a condition known as hairy tongue, which makes what are known as filiform papillae bulges on the upper surface of the tongue discolored and elongated. The American Academy of Oral Medicine says that hairy tongue occurs in as much as 13% of the population, and is harmless and relatively common.

Smoking, bad oral hygiene, and soft foods can cause hairy tongue

Filiform papillae are bulges under the mucous membrane of the tongue, which help to roughen the surface and help with chewing, speaking, and keeping your mouth clean.

Usually, the filiform papillae are worn down from regular brushing and eating solid foods. But the protein keratin can build up on these papillae if there is a lack of abrasion to the top of the tongue, according to the AAOM. So people are more at risk of developing hairy tongue if they have poor oral hygiene or are on soft food diets as a result of other health issues or lack of teeth, for example.

When the filiform papillae are allowed to build up for a while, they can get very long and develop a hair-like appearance. They can then trap bacteria, yeast, and food, which add to the buildup.

Smoking can also increase your risk of hairy tongue, because it facilitates the buildup of bacteria and plaque on your tongue, as can taking certain medications like antibiotics, which can change the types of bacteria in your mouth and again cause buildup.

Usually with hairy tongue, the filiform papillae turn black, but they can also go brown, yellow, or green — like in this patient's case.

Hairy tongue is more common in older age, as well as in men, according to the AAOM.

Hairy tongue doesn't require any medication for its treatment. In this case, the patient was advised to gently scrub the surface of his tongue with a toothbrush four times daily, and to stop smoking.

Six months after he first presented with hairy tongue, it had returned to normal despite the fact that he did not stop smoking.