What is glossitis and what causes it?

The top of a healthy tongue is matte and slightly rough because it is covered with papillae, including the threadlike filiform papillae that give it a velvety look. In glossitis these papillae shrink or disappear, so the tongue looks:

• Smooth, glossy or "bald" in patches or all over
• Bright red, beefy, or sometimes pale
• Swollen, sometimes with tooth marks along the edges

It can feel sore, tender or burning, especially with hot, spicy or acidic food. MedlinePlus notes that symptoms can start suddenly or develop slowly, and swelling can make chewing, swallowing or speaking harder. Rarely, it swells enough to block the airway.

Nutritional deficiencies

This is the cause most people worry about, and it is a real one. The NHS lists a sore or red tongue, sometimes with mouth ulcers, among the symptoms of vitamin B12 or folate deficiency anemia; MedlinePlus describes a swollen, red tongue in B12 deficiency. A case-control study in PMC found B12 deficiency may play a role in atrophic (smooth) glossitis. Iron, riboflavin and niacin deficiencies can also contribute. Tiredness, breathlessness and pins and needles alongside a sore smooth tongue make deficiency more likely.

Allergies and irritants

Reactions to foods, medicines, toothpaste or mouthwash ingredients can inflame the tongue. Tobacco, alcohol and very spicy food irritate it directly.

Infections

Yeast (thrush), viruses including herpes simplex and bacteria can all cause glossitis. A related pattern, median rhomboid glossitis, is a smooth red patch in the middle of the top of the tongue; a case-control study in PMC found it was considerably more common in people with diabetes.

Dry mouth

Saliva protects the tongue. Dry mouth from medicines or Sjögren's syndrome leaves it more prone to inflammation.

Injury and appliances

Burns, biting, rough teeth and ill-fitting dentures can cause localized glossitis.

A dentist or doctor will examine the tongue for missing papillae and swelling, ask about diet, medicines, recent illness, alcohol and tobacco, and check the rest of the mouth. MedlinePlus notes that blood tests may be needed to look for an underlying problem; typical tests include a full blood count, iron studies, vitamin B12 and folate. A swab may be taken if yeast is suspected.

Treatment targets the cause, and Cleveland Clinic and MedlinePlus both describe glossitis as going away once that cause is removed or treated. Depending on the cause, that may mean:

• Antifungal, antiviral or antibiotic medicine for infection
• Supplements or diet changes once a deficiency is confirmed by testing
• A corticosteroid applied to the tongue to calm inflammation
• Stopping or switching a medicine or product causing a reaction
• Adjusting dentures or smoothing sharp teeth

At home, avoid hot, spicy and acidic food, alcohol and tobacco while the tongue is sore, use a mild toothpaste, and keep up thorough but gentle oral care. Cleveland Clinic notes that brushing the tongue as part of good oral hygiene helps lower the risk of infection-related glossitis. Clean gently and skip areas that are raw.

MedlinePlus advises contacting a provider if symptoms last longer than 10 days, if swelling is severe, or if speaking, chewing or swallowing becomes difficult. Get emergency care right away if tongue swelling affects breathing.