Dry Mouth (Xerostomia): Why It Happens and How to Treat It

Dry mouth — known medically as xerostomia — is the feeling that there is not enough saliva in the mouth. Everyone has a dry mouth occasionally, especially when they are nervous, upset, or under stress. But persistent dry mouth, lasting weeks or months, is a medical condition that requires evaluation.

According to the National Institute of Dental and Craniofacial Research (NIDCR), dry mouth is not a normal part of aging. When it occurs in older adults, it is almost always due to a medication, a medical condition, or a treatment such as radiation — and not aging itself.

Saliva does much more than keep the mouth feeling comfortable. Healthy salivary flow:

• Washes away food particles that bacteria would otherwise feed on
• Neutralizes acids produced by bacteria, protecting tooth enamel
• Delivers calcium, phosphate, and fluoride to help re-mineralize early tooth decay
• Contains antibacterial proteins that limit microbial growth
• Begins the chemical digestion of food
• Lubricates the mouth to make speaking, chewing, and swallowing possible
• Maintains the health of the soft tissues of the mouth

When salivary flow drops, all of these protections drop with it. This is why chronic dry mouth dramatically raises the risk of cavities, gum disease, and oral infections.

• A sticky, dry feeling in the mouth
• Trouble chewing, swallowing, tasting, or speaking
• A burning feeling in the mouth
• Dry feeling in the throat
• Cracked lips and corners of the mouth
• A dry, rough tongue
• Mouth sores
• An infection in the mouth
• Bad breath
• A frequent need to sip water during meals
• Difficulty wearing dentures

Without adequate saliva, the mouth loses one of its main natural defenses against decay. People with chronic xerostomia can develop:

• Rampant cavities — particularly at the gum line and on tooth roots
• Rapidly progressive gum disease
• Oral yeast infections (oral candidiasis or 'thrush')
• Difficulty chewing and swallowing, which can affect nutrition
• Loose dentures and denture-related sores

NIDCR specifically warns that patients receiving head and neck radiation, patients taking polypharmacy regimens, and patients with Sjögren's syndrome are at very high risk for radiation caries or 'medication-related decay' — and need an aggressive preventive plan.

Medications

More than 400 commonly prescribed medications can cause dry mouth. The most common categories include:

• Antihistamines
• Decongestants
• Antidepressants
• Antipsychotics
• Anti-anxiety medications
• Diuretics ('water pills')
• Antihypertensives (blood pressure medications)
• Pain medications
• Bronchodilators (asthma inhalers)
• Muscle relaxants
• Anti-Parkinson agents
• Some chemotherapy drugs

People taking multiple medications often experience an additive effect.

Medical conditions

Several conditions can cause chronic dry mouth, including:

• Sjögren's syndrome — an autoimmune disease that specifically attacks the salivary and tear glands
• Diabetes (especially poorly controlled diabetes)
• HIV/AIDS
• Parkinson's disease
• Alzheimer's disease
• Stroke (which can cause altered consciousness or reduced sensation)
• Anemia
• Cystic fibrosis
• Rheumatoid arthritis

Cancer treatment

• Radiation therapy to the head and neck region directly damages salivary glands. Salivary flow may be permanently reduced.
• Chemotherapy can alter the composition of saliva and reduce flow temporarily.

Nerve damage

Injuries or surgery to the head and neck region can damage the nerves that signal the salivary glands to produce saliva.

Dehydration

Vomiting, diarrhea, blood loss, sweating, and inadequate fluid intake can all cause temporary dry mouth that resolves with rehydration.

Tobacco and alcohol use

Both reduce salivary flow and worsen dry mouth symptoms.

NIDCR recommends a tiered approach:

Step 1: Identify and address the cause

• Review medications with the prescribing physician — many drugs have less drying alternatives
• Treat underlying medical conditions (improve diabetes control, address autoimmune disease, etc.)
• Stop tobacco and reduce alcohol

Step 2: Stimulate natural saliva flow

• Sugar-free gum or candy (especially xylitol-sweetened) — chewing stimulates saliva production
• Sip water frequently throughout the day
• Avoid caffeine, alcohol, and tobacco, which worsen drying
• Use a humidifier at night, especially in dry climates or heated bedrooms

Step 3: Substitute saliva when natural production is too low

• Over-the-counter saliva substitutes (Biotène, MouthKote, Oasis) — available as sprays, gels, and rinses
• Prescription medications such as pilocarpine (Salagen) and cevimeline (Evoxac) can stimulate salivary glands when residual gland function remains

Step 4: Aggressive dental prevention

For patients with significant chronic xerostomia, standard preventive measures are not enough.

• High-strength prescription fluoride toothpaste (5,000 ppm)
• Daily fluoride rinses or custom fluoride trays used nightly
• Quarterly dental cleanings instead of twice-yearly
• Frequent fluoride varnish applications in office
• Diet counseling to limit fermentable carbohydrates and acidic drinks
• Sealants on at-risk tooth surfaces

If dry mouth has lasted more than a few weeks, see a dentist or physician. Persistent xerostomia is often the first sign of a treatable underlying condition. A dentist can also start the preventive plan that prevents the long-term damage of untreated dry mouth.

Dry mouth is far more than a comfort issue — it is a dental and medical condition that, untreated, leads to rampant decay, gum disease, and infection. The good news: for most patients, identifying the cause, stimulating saliva production, and putting an aggressive preventive plan in place dramatically reduces both symptoms and dental damage.

This article is adapted from public-domain content published by the U.S. National Institute of Dental and Craniofacial Research (NIDCR) and the National Institutes of Health (NIH).