How the tongue stays moist?
The moistness of the tongue is due to saliva. There are three major groups of salivary glands that are responsible for the production of saliva. These are the parotid glands, submandibular glands, and the sublingual glands. In addition to these, hundreds of minor salivary glands also exist in the mouth. These minor salivary glands have a small but significant contribution to the overall saliva production in the mouth.
Read more on tongue anatomy.
Saliva is a watery substance that contains mucus and digestive enzymes. The amount of saliva production per day can range from 0.8 liters to 2 liters. The moistness of the tongue and the mouth is dependent on the balance between the rate of saliva secretion and the rate of saliva drainage or evaporation.
Loss of moisture through evaporation is not very significant in conditions when the mouth is kept closed most of the time. Excess saliva in the mouth is usually swallowed. Also, some amount of saliva in the mouth constantly drains down the back of the throat. Saliva secretion increases during eating. Smells, sights and thoughts of appealing foods can also increase the secretion of saliva in the mouth.
Why does the tongue become dry?
When the rate of loss of saliva is balanced by the rate of saliva secretion, the mouth and tongue remain comfortably moist. However, if the rate of loss of saliva exceeds the rate of saliva secretion, then dryness ensues. Reduction in the production of saliva in the mouth causes dryness of the mouth (technically known as xerostomia). A dry mouth also means a dry tongue.
In fact, dryness in the mouth is more readily experienced as a thick and hairy sensation on the tongue. In many cases, a dry mouth is a temporary condition that is not caused by any disease. In such cases, a dry mouth can be easily remedied by consumption of a significant quantity of water. However, in some cases, the dryness of the mouth and the tongue may be more persistent.
Disruption of saliva production or secretion due to some underlying pathology is more likely the cause in such cases. Both local disorders of the salivary glands and systemic disturbances can affect production and secretion of saliva. In fact, a persistent dry mouth and tongue may be an early symptom of diseases like Sjogren’s syndrome and diabetes mellitus. A dry mouth is often associated with excessive thirst in such conditions.
Lifestyle Causes of a Dry Tongue
Both diseases and lifestyle factors can cause dryness of the tongue and mouth. The following are some of the lifestyle factors that can cause a dry tongue.
Breathing through the mouth can lead to dryness of the mouth and the tongue. Compared to nose breathing, mouth breathing is characterized by an increased air flow through the oral cavity. Under normal circumstances, we breathe mostly through the nose. However, mouth breathing may increase in certain conditions such as strenuous physical activity, nasal congestion, blood disorders, heart disease and lung disease.
The rate of saliva secretion is at its lowest level during sleep. Therefore, it is entirely normal to wake up with a relatively dry mouth in the morning. Mouth dryness may worsen if sleep is accompanied by snoring and mouth breathing.
Age-related changes in the salivary glands lead to decreased production of saliva in old age. Disruption of nerve signals to the salivary gland may also decrease the secretion of saliva.
Consumption of certain foods can have a dryness-inducing effect in the mouth. These foods tend to absorb the moisture in the mouth. Examples of such foods include starchy foods made from refined corn or wheat flour, candies, sugar, and salt.
Mouth dryness is a common occurrence in people who consume tobacco. Both chewing and smoking tobacco can result in a dry tongue. Stopping consumption of tobacco products improves the condition.
Alcohol is a known drying agent and diuretic. Excessive intake of alcohol can lead to a dry mouth and a dry tongue.
Disease Causes of a Dry Tongue
The following are some of the diseases that can cause dry mouth and dry tongue.
Salivary gland problems
A variety of diseases that affect the salivary gland can decrease the production or secretion of saliva. Examples of such salivary gland diseases include infections, inflammation, salivary stones, and tumors. These diseases can either damage the secretory tissue of the salivary gland or block the salivary ducts through which saliva is secreted.
A major portion of our body is made up of water. Without adequate amount of water, the normal biological processes within the body cannot occur. Since a major part of saliva also consists of water, dehydration (loss of water and electrolytes) can lead to a decrease in the amount of saliva present in the mouth.
Sjogren’s syndrome is an autoimmune disorder in which the salivary glands are attacked by the body’s immune system. Excessive dryness in the mouth and constant thirst are two of the main features of this condition.
Diabetes mellitus is caused by insulin deficiency or insulin resistance. Excessive thirst, dry mouth and dry tongue are characteristic features of this condition.
Dryness of mouth is very commonly reported by AIDS patients. In conjunction with a weakened immune system, the dry mouth and tongue in AIDS patients predispose them to fungal infections such as the oral thrush.
Read more on burning tongue.
Hypothyroidism is characterized by low levels of thyroid hormones in the body. Dry tongue and dry mouth are also commonly present in this condition.
Nerve disease or damage
Secretion of saliva can get affected by damage to the nerves that innervate the salivary gland. This may occur in conditions such as surgery, trauma to the head and face, and infections of the nervous system.
Dry mouth and dry tongue are common side-effects of many over-the-counter and prescription drugs. Saliva production usually normalizes upon discontinuation of the drug.
Remedies for Dry Tongue
Remedies for dry tongue and mouth depend on the underlying cause of the dryness. Changes in lifestyle may help in certain conditions. Medical treatment may be required if a disease is responsible for the dry tongue.
Some of the lifestyle changes that may help include increased water intake, avoidance of dryness-inducing foods and beverages (such as starch, sugar, salt, acids, tobacco, and alcohol), use of air humidifiers, and measures to avoid mouth breathing.