What causes macroglossia (an enlarged tongue)?

Doctors separate two situations, because they are treated differently:

• True macroglossia: the tongue tissue itself is enlarged, from extra muscle, fluid, deposits or a growth.
• Pseudomacroglossia: the tongue is a normal size but looks too big because the space around it is small, for example a small lower jaw, a narrow dental arch, a low palate or very large tonsils pushing it forward. A review in PMC lists these as common mimics.

A tongue that is temporarily swollen from an allergy, injury or infection is a different problem again; see swollen tongue. Sudden swelling is an emergency, while macroglossia develops over time or is present from birth.

• Beckwith-Wiedemann syndrome: a growth disorder. Cleveland Clinic notes that about 90% of children with it have macroglossia.
• Down syndrome: listed by Cleveland Clinic and MedlinePlus among the conditions most often linked to an enlarged tongue.
• Congenital hypothyroidism: low thyroid hormone from birth; Cleveland Clinic calls hypothyroidism a common cause in children.
• Lymphangioma and hemangioma: malformations of lymph or blood vessels within the tongue.
• Mucopolysaccharidoses such as Hurler and Hunter syndromes, in which sugar molecules build up in tissues.

Some children with a large tongue at birth grow into it as the face and jaw develop.

• Hypothyroidism: fluid and tissue changes can enlarge the tongue, often with tiredness, weight gain and feeling cold.
• Acromegaly: excess growth hormone, usually from a pituitary tumor, enlarges the tongue along with the hands, feet and facial features. The NHS describes it as a rare condition that develops slowly.
• Amyloidosis: abnormal protein deposits; Cleveland Clinic notes macroglossia is the most common oral sign of amyloidosis. It can come with scalloping along the edges.
• Tumors: such as lymphoma, or vascular growths.
• Infections and inflammation: including tuberculosis, sarcoidosis and, historically, diphtheria.
• Medicines, radiation, injury or surgery affecting the tongue.

These effects, compiled from Cleveland Clinic and a PMC review, are what decide whether treatment is needed, more than the size of the tongue alone.

A doctor examines the tongue, mouth, head and neck and looks for signs of an underlying condition. Blood tests such as thyroid function may be ordered, and CT or MRI scans can show the tongue structure or a vascular malformation.

Treatment starts with the cause:

• Thyroid hormone replacement for hypothyroidism, or treatment of acromegaly or amyloidosis
• Corticosteroids in some cases to reduce swelling
• Speech therapy and feeding support
• Orthodontic treatment for bite problems
• Reduction glossectomy, surgery to remove part of the tongue, for severe cases affecting breathing, feeding or jaw growth

Cleveland Clinic reports that about 10% of people treated for macroglossia have surgery to reduce the size of their tongue.

Day to day, keeping the mouth comfortable matters. If the tongue often rests outside the lips, regular sips of water and lip balm help keep the mouth comfortable. Good tooth brushing and regular dental visits are important when the bite is affected. Tongue coating care is the same as for anyone else, but there is no evidence that oral hygiene changes the size of the tongue.