Conditions: Xerostomia (Dry Mouth)
Xerostomia is the medical term for the sensation of a dry mouth. It is a symptom rather than a disease in itself, and it can reflect reduced saliva production or changes in the quality of saliva.
What is xerostomia?
Xerostomia is the medical term for the subjective feeling of a dry mouth. It is a symptom rather than a disease in itself, and it often points to an underlying cause that affects how the mouth makes or holds onto saliva.
Doctors distinguish two related terms. Xerostomia is the sensation of dryness a person notices. Salivary gland hypofunction (also called hyposalivation) is a measured reduction in the actual amount of saliva produced. The two do not always go together—some people feel very dry even when their saliva flow tests as normal, because the problem can lie in the quality and thickness of saliva rather than its quantity. Dry mouth is common, with population studies estimating that roughly one in five to one in four people report symptoms, and it becomes more frequent with age.
How saliva works and why it matters
Saliva is produced by three pairs of major salivary glands—the parotid, submandibular, and sublingual glands—along with hundreds of tiny minor glands scattered throughout the lining of the mouth. Healthy adults make roughly 1 to 1.5 liters of saliva each day. Production rises during and after meals and drops during sleep. It is controlled by the nervous system, which is why the sight, smell, or taste of food can trigger the glands to release saliva.
Although saliva is about 99% water, the rest contains proteins, minerals, and enzymes that do a great deal of work. Saliva:
Lubricates and moistens the lining of the mouth and the teeth, making chewing, swallowing, and speaking possible.
Protects the teeth by buffering acids, keeping the mouth near a neutral pH, and supplying minerals that help repair (remineralize) tooth enamel.
Cleanses the mouth by washing away food debris and microorganisms.
Fights infection through antibacterial, antiviral, and antifungal substances that help keep the mix of germs in the mouth in balance.
Supports taste and digestion by dissolving flavor molecules so they can reach the taste buds, and by beginning the breakdown of starches.
Aids wound healing in the tissues of the mouth.
When saliva flow falls or its composition changes, all of these protective functions are weakened, which is why dry mouth can lead to a chain of further problems.
Common causes
Dry mouth has many possible causes, and more than one can be present at the same time.
Medications. This is the most common cause overall. Hundreds of drugs can reduce saliva, including many antidepressants, antihistamines, medications for high blood pressure, diuretics ("water pills"), medications for overactive bladder, and other anticholinergic drugs. Taking several medications at once (polypharmacy), common in older adults, increases the likelihood of dry mouth.
Radiation therapy to the head and neck. Radiation used to treat cancers of the head and neck can damage the salivary glands directly. Depending on the dose and the area treated, this dryness can be severe and long-lasting or permanent. Modern radiation techniques that spare the salivary glands can reduce this effect.
Sjögren syndrome and other medical conditions. Sjögren syndrome is an autoimmune disorder in which the immune system attacks the moisture-producing glands, causing dry mouth and dry eyes; it is far more common in women. Other conditions linked to dry mouth include diabetes, other autoimmune diseases (such as rheumatoid arthritis and lupus), graft-versus-host disease after stem cell transplant, HIV, and treatment with certain cancer immunotherapies.
Dehydration. Not taking in enough fluid, or losing fluid through fever, vomiting, or diarrhea, lowers the water available for saliva.
Mouth breathing. Breathing through the mouth, especially during sleep or with nasal congestion or obstruction, dries out the oral tissues.
Other factors. Aging, tobacco and alcohol use, anxiety and depression, and nerve damage affecting the salivary glands can all contribute.
Symptoms and complications
The most obvious symptom is a persistent dry, sticky feeling in the mouth, sometimes with thick or stringy saliva, cracked lips, or a dry throat. Because saliva does so much, reduced flow can cause a range of further symptoms and complications:
Tooth decay (dental caries). Without saliva's cleansing, buffering, and remineralizing effects, cavities can develop quickly and in unusual patterns. After head and neck radiation, decay can appear within the first few months and can lead to more serious problems in the teeth and jawbone.
Oral infections. A dry mouth is more prone to fungal infections, especially oral thrush (candidiasis), as well as gum disease.
Difficulty chewing, swallowing, and speaking. A poorly lubricated mouth makes forming and swallowing food harder and can make speech difficult; some people need to sip liquids to talk or eat.
Taste changes. Because saliva helps carry flavors to the taste buds, dry mouth can dull or alter taste (dysgeusia).
Other effects. Bad breath (halitosis), a burning or sore mouth, mouth ulcers, and trouble keeping dentures in place are common. Over time, difficulty eating can contribute to poor nutrition and weight loss, and the day-to-day burden can affect quality of life.
How xerostomia is evaluated
Because dry mouth can have many causes, evaluation usually begins with a thorough medical, dental, and medication history to look for likely contributors—especially medications, radiation history, and signs of conditions such as Sjögren syndrome. A careful examination of the mouth, head, and neck checks the condition of the teeth and gums, looks at the moisture and health of the oral lining, and feels the salivary glands for swelling, masses, or asymmetry.
Symptoms may be assessed with simple questions or with standardized questionnaires. To measure saliva objectively, a test called sialometry collects and measures the amount of saliva produced over a set period, both at rest (unstimulated) and while chewing something like paraffin wax (stimulated). Very low flow rates support a diagnosis of salivary gland hypofunction. Depending on the suspected cause, additional tests—such as blood tests for autoimmune disease, imaging of the glands, or a small gland biopsy—may be used.
Treatment and management
There is no single cure for dry mouth, and treatment is tailored to the cause and severity. In general, care focuses on relieving symptoms, protecting the teeth and mouth, and addressing whatever is driving the dryness. Common approaches include:
Addressing the underlying cause. When a medication is responsible, the prescribing clinician may consider adjusting the dose or switching to an alternative with less drying effect. Managing conditions such as diabetes or Sjögren syndrome, and correcting dehydration, can also help.
Medication review. Reviewing the full list of medications, particularly in people taking many drugs, can identify contributors that might be changed.
Hydration and environment. Frequent sips of water and steps to keep the air and mouth moist, such as using a humidifier, are simple measures commonly used.
Saliva substitutes and moisturizers. Artificial salivas and oral moisturizers come as sprays, gels, rinses, and toothpastes. They coat and lubricate the mouth and generally last longer than water. Products with a neutral pH and added fluoride are generally favored because they are gentler on the teeth and support enamel.
Saliva stimulants (sialogogues). When the glands are still able to work, stimulating saliva is often more effective than substituting it. Non-drug stimulants include sugar-free gum, lozenges, and xylitol or sugar-free acidic candies. Prescription medications called cholinergic agonists—such as pilocarpine and cevimeline—can increase saliva flow and have improved symptoms in people who have had head and neck radiation or who have Sjögren syndrome. These drugs can cause side effects such as sweating and require caution in people with certain heart or lung conditions, such as asthma or chronic lung disease.
Dental care. Because of the high risk of decay, preventive dental care is central. This typically includes meticulous daily brushing and flossing, regular dental visits, limiting sugary and acidic foods and drinks, and high-strength fluoride (such as prescription fluoride gels, pastes, or varnishes). Antifungal treatment is used when candidiasis develops.
The overall goal is to keep the mouth comfortable and functional while protecting the teeth and preventing infection. A combination of approaches is often used, and the right mix depends on the underlying cause and how well the salivary glands can still respond.