Dry mouth

About 10% of the general population and 25% of older people experience dry mouth (not enough saliva in the mouth). A dry mouth is a symptom of an underlying problem, rather than a condition in itself.

A number of things may cause a persistently dry mouth, including prescription medications, medical treatments and certain autoimmune diseases such as Sjogren's disease.

Treatment includes products that help to moisten the mouth. The feeling of a dry mouth is also called xerostomia.

Salivary glands

The salivary glands are located around the mouth and throat. These glands make saliva which is pumped into the mouth along tiny channels called salivary ducts. The salivary glands include:

• Parotid - located in the cheek between the front of the ear and the last tooth.
• Submandibular - located beneath the tongue on both sides of the jaw (mandible).
• Sublingual - located in the floor of the mouth.
• Minor salivary glands - found in various locations around the mouth, including the inner cheeks and throat.

A steady flow of saliva keeps the mouth moist at all times. Chewing and swallowing food increases the flow of saliva. Simply looking at and thinking about appetising food can also cause an increased saliva flow.

Protective role of saliva

A dry mouth significantly increases the risk of tooth decay and other oral diseases. Having enough saliva keeps your mouth healthy as it:

• has components that can directly attack the bacteria that cause decay
• has anti-fungal properties
• helps to destroy viruses
• neutralises the harmful acids produced by bacteria in plaque
• contains calcium and phosphate which are important for preventing and healing damage caused by tooth decay
• moistens food which allows you to swallow comfortably
• helps with the formation of particular sounds when you speak
• boosts sensation inside the mouth and allows the experience of food texture, taste and also pain if something is wrong.

Symptoms of dry mouth

Dry mouth symptoms may include:

• saliva that feels thick or stringy
• a rough, dry tongue
• the tongue tending to stick against the roof of the mouth, or lips and cheeks tending to stick against the gums
• problems with chewing or swallowing (particularly dry foods such as biscuits)
• bad breath
• mouth ulcers
• dry and cracked lips
• susceptibility to oral thrush infections
• a high rate of tooth decay
• a prickly, burning sensation in the mouth
• loose acrylic (non-metal) dentures as saliva helps to create the suction between the gum tissues and the acrylic base of the denture.

Related symptoms in the rest of the body

Depending on the cause, dry mouth may relate to symptoms outside the mouth, including:

• dry and itchy eyes
• dry nose or throat
• frequent coughing
• reduced sense of smell
• constipation
• joint pains or stiffness
• generally feeling unwell
• interrupted or poor quality of sleep
• unexplained weight loss
• in women, frequent vaginal thrush infections.

Speak to your doctor if you're experiencing some of these issues so that they can look into what might be causing them.

Dry mouth and tooth decay

Poor oral hygiene (not brushing and flossing your teeth every day) and a sugary diet tend to cause tooth decay. Because they are lacking the protection of saliva, people with dry mouth are more likely to get tooth decay and are more prone to get decay along the gum line (tooth root surface).

Unlike enamel (the outer tooth layer), dentine (the inner tooth layer) is less resistance to acids and can decay quickly, especially without enough saliva to protect it. People with dry mouth may also develop decay on the lower front teeth, which are normally well protected by saliva produced from beneath the tongue.

While people with dry mouth are more prone to decay, it is still preventable with the right diet and lifestyle. Thorough teeth cleaning with a suitable fluoride toothpaste is extremely important.

Causes of dry mouth

Many different conditions, some short term and others long term, can disrupt the production of saliva. These conditions may include:

• Drugs and medications - about 600 drugs and medications, both legal and illegal, are known to cause dry mouth. These include antihistamines, high blood pressure medications, sedatives, decongestants, analgesics (pain relief), antidepressants and illegal drugs such as cocaine.
• Infection - a bacterial or viral infection of the salivary glands (such as mumps) can cause inflammation and restrict saliva production.
• Salivary duct blockages - for example, tiny stones made from saliva minerals may lodge in the salivary ducts and restrict saliva flow.
• Certain medical conditions - including AIDS, amyloidosis, cerebral palsy, diabetes, Parkinson's disease, primary biliary cirrhosis and lupus.
• Nerve problems - the function of the salivary glands is controlled by facial nerves. Injury, illness or surgical damage to these nerves, for example, may reduce saliva production.
• Some cancer treatments - such as chemotherapy or radiotherapy (if directed at the head or neck), may temporarily reduce the ability of salivary glands to make saliva.
• Other causes - including a tendency to mostly breathing through the mouth, for example, in the case of a persistently stuffy nose or blocked sinuses, or hormone changes from pregnancy or menopause.
• Dehydration - not drinking enough fluid can cause thick saliva and a dry mouth. Other causes of dehydration include medical conditions such as blood loss, chronic diarrhoea or kidney failure.

Diagnosis of dry mouth

Diagnosis of dry mouth may include:

• Examination of the mouth and teeth - the inner cheeks appear dry and rough, rather than moist and shiny. Your dentist may check the pattern of tooth decay.
• Saliva tests - for example, a typical saliva test involves rolling out the lower lip and patting it dry. Normally, saliva should re-moisten the lower lip within half a minute or so.
• Reviewing medical history - to check for conditions or medicines that could be drying out your mouth.
• Reviewing your symptoms.

Treatment of dry mouth

Treatment depends on the cause, but may include:

• Changes to medicines - if you are taking a medicine that causes dry mouth as a side effect, the doctor who prescribed it may be able to change the dose or prescribe something different.
• Saliva substitutes - your doctor or dentist can prescribe an artificial saliva substitute. Use strictly as directed.
• Dry mouth products - these products contain ingredients such as lubricants that may help treat your dry mouth. The product range includes toothpaste, mouthwash, gums and topical gels. Speak to your dentist for recommendations.
• Dental products - these products may contain high fluoride or calcium to help prevent tooth decay. Speak to your dentist for recommendations.
• Antibiotics and anti-fungal drugs - may be used to treat an infection.
• Surgery - salivary gland blockages, such as stones, are usually treated with minor surgery.
• Other treatments, if required - any underlying condition, such as Sjogren's disease or diabetes, needs appropriate medical treatment.

Tips for living with dry mouth

Be guided by your doctor and dentist, but general suggestions for your diet include:

• Avoid any substance that increases or irritates mouth dryness. These include:
  • cigarettes,
  • e-cigarettes,
  • alcohol,
  • caffeinated drinks and
  • spicy foods.
• Eat chewy foods to stimulate the flow of saliva.
• Chew food thoroughly before swallowing.
• Include watery foods in your daily diet.
• Avoid crunchy foods that could injure the mouth, such as crackers or potato crisps.
• Avoid sugary foods and drinks.
• Avoid acidic foods and beverages, such as soft drinks, energy drinks, sports drinks, cordials, citrus fruits and fruit juices. These drinks are damaging to enamel and may also be high in sugar.
• Avoid lollies (especially fruit-flavoured and sour lollies) and alcohol-containing mouthwashes, as these products tend to aggravate dry mouth tissue.
• Chew sugar-free gum between meals to promote the flow of saliva.
• Drink plenty of water, but avoid sipping slowly as this can wash away any saliva. It may help to carry a drink bottle.
• Ask your dentist for other dietary suggestions, including a complete list of foods and drinks to limit or avoid.

Self-care suggestions for dry mouth

Be guided by your doctor and dentist, but general self-care suggestions include:

• Brush your teeth at least twice a day and floss or use interdental brushes once a day.
• Regularly use fluoride-containing products such as toothpaste. Ask your dentist about which ones are best for dry mouth.
• Treat dry lips with Vaseline or some other type of greasy balm, such as lanolin.
• An air humidifier used in your bedroom at night may help.
• Ask your dentist for more information if you wear dentures - adhesive dental products may be recommended.
• Take out partial or full dentures while you sleep.
• Visit your dentist every 6 to 12 months for check-ups, teeth cleaning and treatment if necessary. You may require more frequent visits if you have a higher risk for tooth decay.
• Continue to take your medication, even if your medicine is to blame. Your doctor may not be able to change it or change the dose. Do not stop taking your medicine without speaking to your doctor.

Where to get help

• Your dentist
• Your GP (doctor)
• Australian Dental Association - Find a dentist Tel. (03) 8825 4600
• Oral Health Victoria provides public dental services through the Royal Dental Hospital Melbourne and public dental clinics for eligible people