Dental Conditions
Dry mouth
Saliva does far more than keep your mouth comfortable. When there is not enough of it, cavities, gum problems and bad breath follow. Here is why it happens and what can be done.
Reviewed by Dr. Ray Han, General Dentist, Dentistry at Vitality Health
Dry mouth, known medically as xerostomia, is the feeling that there is not enough saliva in your mouth. The most common cause by far is medication: hundreds of everyday prescriptions list dry mouth as a side effect. It matters because saliva protects teeth. Without enough of it, cavities form quickly, especially along the roots, and gums and breath suffer. Dry mouth can be managed, and the teeth can be protected.
Many people assume a dry mouth is just a nuisance, or a normal part of getting older. It is neither. It is a warning sign that the mouth has lost its main defence, and it is one of the most common reasons we see new cavities in people who have not had one in decades.
This page explains what saliva does, what causes dry mouth, why it leads to decay and bad breath, what you can do at home, what we can do in the office, and when to see your physician.
What does saliva actually do?
- Washes the teeth. Saliva rinses away food and sugar and dilutes the acid that bacteria produce.
- Neutralizes acid. It buffers the mouth back to a safe level after every meal, which is when enamel would otherwise dissolve.
- Repairs enamel. Saliva carries calcium and phosphate that redeposit into early, soft spots in the enamel before they become cavities.
- Fights germs. It contains proteins and antibodies that keep bacteria and yeast in check.
- Helps you chew, swallow, taste and speak. It moistens food and lubricates the tongue and lips. Dentures need saliva to seal and stay in place.
Most adults produce about a litre of saliva a day. When production falls, all of these jobs suffer at once.
What causes dry mouth?
Medications
The most common cause. Blood pressure pills, antidepressants, antihistamines, decongestants, bladder medicines, painkillers, muscle relaxants and many others reduce saliva. The more medications you take, the greater the effect. Never stop a medication on your own; talk to your physician or pharmacist.
Ageing
Saliva glands do not fail simply from age, but older adults take more medications and have more health conditions that dry the mouth, so dry mouth becomes far more common with age.
Mouth breathing
Breathing through the mouth at night, often because of a blocked nose, snoring or sleep apnea, dries the tissues by morning. A dry mouth on waking that improves through the day is the typical pattern.
Diabetes
High blood sugar pulls fluid from the body and can reduce saliva. Dry mouth is sometimes the symptom that leads to a diagnosis of diabetes, and people with diabetes are already at higher risk of gum disease.
Radiation treatment
Radiotherapy to the head or neck for cancer can damage the saliva glands for the long term. Patients need an intensive prevention plan before, during and after treatment.
Sjögren's syndrome
An autoimmune condition in which the body attacks its own moisture-producing glands, causing dry mouth and dry eyes. It is diagnosed by a physician, usually a rheumatologist, and needs coordinated care.
Why does dry mouth cause cavities and bad breath?
Without saliva to rinse and buffer the mouth, the acid that bacteria produce after every meal or drink stays on the teeth for far longer. Enamel dissolves faster than it can repair. Cavities appear in places that were never a problem before, and they progress quickly.
The roots of the teeth are the most vulnerable. Root surfaces are exposed as gums recede with age, and they are made of a softer material than enamel. Root decay along the gum line is the classic pattern in older adults with dry mouth, and it can undermine a tooth, or a crown, in months. Read more about cavities and tooth decay and receding gums.
Bad breath follows for the same reason. Saliva normally clears the bacteria and food debris that produce odour; a dry mouth lets them build up, particularly on the tongue. A dry mouth is also more prone to thrush, a yeast infection that leaves white patches and a sore, burning feeling, and to cracked lips and corners of the mouth. See our page on bad breath.
What helps at home?
- Sip water often through the day, and keep a glass by the bed. Small frequent sips help more than large drinks.
- Chew sugar-free gum or suck sugar-free lozenges, ideally ones sweetened with xylitol, to stimulate whatever saliva your glands can still make.
- Choose alcohol-free mouth rinses; alcohol dries the mouth further. Rinses and gels made for dry mouth can be soothing, especially at night.
- Run a humidifier in the bedroom, and if you breathe through your mouth at night, ask your physician about the cause.
- Cut back on caffeine, alcohol and tobacco, all of which dry the mouth.
- Limit sugar and acid. Frequent sugary or acidic drinks are far more damaging when there is no saliva to wash them away. Water is the drink of choice.
- Brush twice a day with fluoride toothpaste and clean between the teeth daily, and take dentures out at night and clean them thoroughly.
What can the dental team do?
Our goal is to protect the teeth while the cause is addressed. Depending on your risk, we may recommend:
- Fluoride varnish painted on at each visit, which strengthens enamel and exposed roots for months at a time.
- Prescription high-fluoride toothpaste (5,000 parts per million, several times the strength of regular toothpaste) used nightly.
- More frequent cleanings and check-ups, often every three to four months, so early root decay is caught while it is still small enough to treat simply.
- Saliva substitutes and stimulants. Sprays and gels that mimic saliva, and in some cases a prescription medication from your physician that increases saliva flow.
- Treatment for thrush if it develops, and adjustment or relining of dentures that no longer seal well.
- A medication review in coordination with your physician or pharmacist, to see whether a drug that dries the mouth can be changed, dosed differently or taken at another time of day.
If you wear dentures, dry mouth makes them rub and loosen. See our page on dentures for care advice, and tell us if yours have become uncomfortable.
When should I see my physician?
See your family physician if dry mouth started with a new medication, if it comes with dry eyes, joint pain or unusual tiredness, if you are also very thirsty and passing more urine than usual, or if it is severe and constant with no obvious cause. Dry mouth can be the first visible sign of a medical condition, and the medication review that often solves it needs a prescriber.
We are glad to write to your physician with what we have found in your mouth. Dry mouth is managed most effectively together.
Common questions
Is dry mouth a normal part of ageing?+
Not by itself. Healthy saliva glands keep working into old age. Dry mouth becomes more common with age because of medications and health conditions, and both can often be adjusted. Do not accept it as inevitable.
Which medications cause dry mouth?+
Very many, including common ones: blood pressure medications (especially diuretics), antidepressants, antihistamines and decongestants, bladder-control medicines, opioid painkillers, muscle relaxants, some inhalers and some Parkinson's medications. Taking several at once multiplies the effect. Bring your medication list to your dental visit.
Why am I suddenly getting cavities in my sixties?+
Dry mouth is the usual answer. Teeth that were protected by saliva for decades lose that protection when a medication reduces saliva flow, and receded gums expose softer root surfaces. Fluoride varnish, high-fluoride toothpaste and more frequent visits can stop the pattern.
Can dry mouth cause bad breath?+
Yes. Saliva clears the bacteria and debris that produce odour. Without it they build up on the tongue and between the teeth. Treating the dry mouth, cleaning the tongue and staying well hydrated usually improve breath noticeably.
Does chewing gum really help?+
Yes, as long as it is sugar-free. Chewing stimulates the saliva glands, and gum sweetened with xylitol also makes it harder for cavity-causing bacteria to grow. Chewing for ten to twenty minutes after meals is a simple, effective habit.
Sources: Tan ECK, et al. Medications that cause dry mouth as an adverse effect in older people: a systematic review and meta-analysis. J Am Geriatr Soc 2018;66(1):76–84 · Barbe AG. Medication-induced xerostomia and hyposalivation in the elderly: culprits, complications, and management. Drugs Aging 2018;35(10):877–885 · Canadian Dental Association: position on the use of fluorides in caries prevention
Dry mouth and new cavities?
Book a visit and bring your medication list. We will protect your teeth and help you get to the cause. Call (905) 479-7777.