The tongue occupies most of the oral cavity and any disorder affecting the mouth will usually involve the tongue as well. The outer part of the tongue is covered by a mucous membrane similar to most of the inner lining of the mouth. It has various papillae (projections) which house the taste buds. Moisture of the tongue is maintained by saliva, most of which comes from the major salivary glands (parotid, sublingual, submandibular) with a smaller yet significant contribution from the hundreds of minor salivary glands in the mouth. Therefore dryness of the mouth which is primarily due to reduced saliva secretion will also cause dryness of the tongue.
Why is the tongue dry?
A dry tongue is part of mouth dryness (xerostomia). It is sometimes more prominent in the tongue causing a coarse or hairy and thick sensation of the tongue. Most causes of a sudden dryness of the tongue are benign and due to certain foods or situations that are often not related to any disease. It is quickly remedied with significant water consumption. However, persistent dryness of the mouth and tongue are often due to some disruption with saliva secretion that may either be due to local disorders of the salivary glands or systemic disturbances. It is an important early symptom of diseases like diabetes mellitus and Sjogren’s syndrome and is often linked to excessive thirst.
The moisture content within the mouth is a balance between the rate of saliva secretion and drainage down the throat or evaporation from the mouth. Normally the mouth is closed when a person is not eating or talking so the moisture loss by evaporation is minimal. Only excess amounts of saliva are actively swallowed but small quantities are constantly draining into the back of the throat. It is however quickly replaced by the saliva secretion from the salivary glands. In this way the moisture content within the mouth and that of the tongue is consistent. Saliva secretion increases when a person sees and smells foods that are appealing. It also increased when eating. Saliva is a combination of a serous fluid (thin and watery) containing digestive enzymes and mucus which moisturizes the mouth and tongue. About one liter of saliva is secreted per day on average although this can be as low as 0.8 liters or as high as 2 liters.
Causes of a Dry Tongue
Some causes of a dry tongue and mouth dryness are due to factors that may or may not be related to any disease, and includes lifestyle factors. These causes may include :
- Mouth breathing increases the flow of air through the mouth cavity thereby having a drying effect on the tongue. It may arise with heart or lung disease, blood disorders that affect oxygenation, nasal congestion or after strenuous activity.
- Sleep is a period when saliva secretion decreases and is at the lowest level. It is therefore not uncommon to experience moderate mouth dryness upon waking. However, with mouth breathing and snoring during sleep there is excessive mouth and tongue dryness upon waking.
- Aging leads to various changes in different parts of the body including the salivary glands. Less saliva is produced and secreted either due to age-related changes in the salivary gland or disruption of the nerves signals that stimulated saliva secretion.
- Foods particularly refined carbohydrates causes tongue dryness by absorbing moisture in the mouth. This includes sugar, candy, starchy foods made from wheat or corn flour. Salty foods have a similar effect but more often causes the sensation of tongue dryness than actually having a major drying effect. Salt also increases thirst.
- Tobacco use whether through smoking or chewing also contributes to mouth dryness. It usually resolves once tobacco products are stopped.
- Alcohol consumption, especially in large amounts, tends to lead to a dry tongue and mouth in general as alcohol is a diuretic.
Diseases that cause tongue dryness
- Salivary gland diseases may vary from inflammation, infections to tumors and salivary stones. These diseases either block the salivary ducts which carry saliva out of the gland or damage the secretory tissue of the salivary gland.
- Dehydration is a loss of water and electrolytes that is essential to maintain normal body functioning. In an attempt to preserve the body fluids, saliva production and secretion may decrease significantly.
- Sjogren’s syndrome is an autoimmune condition where the immune system attacks and damages the salivary glands and tears glands in particular. Patients typically have excessive dryness of the mouth and complete of continuous thirst.
- Diabetes mellitus is a disorder associated with insulin deficiency or resistance that leads to high blood glucose levels. A dry mouth and tongue as well as excessive thirst are typical symptoms.
- HIV/AIDS patients commonly report dryness of the mouth and tongue. The decreased saliva content in addition the weakened immune defenses increases the chances of conditions such as oral thrush.
- Hypothyroidism is diminished thyroid activity with low thyroid hormone levels. Dryness of the mouth and tongue are one of the symptoms.
- Nerve diseases or damage as a result of trauma to the head or face, surgery or certain infections that target the nerves may affect the relaying of signals that control the activity of the salivary glands.
- Medication is one of the most common side effects of almost any type of over-the-counter and prescription drug. It is usually temporary and resolves once the drug is discontinued. Medication for high blood pressure, diarrhea, nasal and sinus congestion, depression, anxiety, Parkinson’s disease and muscle spasm.
Remedies for Dry Tongue
Although there are certain medication that can increase saliva production, certain lifestyle and home remedies may help ease the dryness. Medical treatment is necessary to treat any underlying diseases as a dry tongue is just one symptom of these diseases.
- Drink sufficient water during the day – between 1.5 to 2 liters. Sip throughout the day rather than drinking large quantities in a few sittings.
- Avoid foods with high quantities of salt, sugar, starch and acids.
- Limit coffee and alcohol intake and stop tobacco use.
- Chewing gum (sugar free) can assist with increasing saliva production.
- Air humidifiers are helpful for dry climates especially at night.
- Use ergonomic pillows to reduce snoring.
- Avoid mouth breathing if voluntary or seek treatment for nasal congestion to stop mouth breathing.