Short answer
Dry mouth, also called xerostomia, happens when the salivary glands do not make enough saliva. The most common cause is medication, but mouth breathing, dehydration, diabetes, Sjögren's disease and head and neck radiation are also common causes. Dryness at night is often linked to mouth breathing, snoring or medications taken in the evening. Sipping water, sugar-free gum or lozenges, a bedroom humidifier and saliva substitutes can help. Because saliva protects teeth, dry mouth raises the risk of cavities, so your dentist may recommend extra fluoride.
Key takeaways
- Hundreds of common medications can reduce saliva, especially when several are taken together.
- Waking with a dry mouth often points to mouth breathing, snoring or evening medications.
- Saliva protects teeth, so dry mouth can lead to a sudden rise in cavities, especially along the gumline.
- Ongoing dry mouth deserves a conversation with your dentist and physician, not just more water.
Everyone gets a dry mouth now and then, when nervous, after a salty meal or after a night of mouth breathing with a cold. But a mouth that feels dry most of the time is different. It is uncomfortable, it can make eating and speaking harder, and it quietly raises the risk of cavities and mouth infections. This guide explains the common causes of dry mouth, why it is often worse at night, remedies that help, and how to protect your teeth.
What is dry mouth?
Dry mouth, or xerostomia, is the feeling that there is not enough saliva in your mouth. It usually happens because the salivary glands are making less saliva than normal, though sometimes saliva is present but thicker than usual.
Saliva does more than keep the mouth wet. It:
- Washes away food and bacteria
- Neutralizes the acids that cause tooth decay
- Brings calcium and phosphate back to the enamel surface to repair early damage
- Helps you taste, chew and swallow
- Contains substances that help control bacteria and fungi
- Helps dentures stay in place
When saliva drops, all of these protections weaken at once.
Common signs of dry mouth
- A sticky, dry or burning feeling in the mouth
- Thick or stringy saliva
- Needing to sip water to talk or swallow dry food
- Bad breath
- Cracked lips, sores at the corners of the mouth or a rough, red tongue
- A changed sense of taste
- Dentures that rub or do not stay in place
- New cavities, especially near the gumline
What causes dry mouth?
Medications
Medication is the most common cause. Hundreds of prescription and over-the-counter drugs list dry mouth as a side effect, including some used for high blood pressure, depression and anxiety, allergies and colds, pain, bladder control and sleep. The more medications a person takes, the more likely dry mouth becomes, which is one reason it is so common in older adults.
Medical conditions
- Sjögren’s disease, an autoimmune condition that affects the glands that make saliva and tears
- Diabetes, especially when blood sugar is not well controlled
- Other conditions, including HIV, some neurological conditions and kidney disease
Cancer treatment
Radiation to the head and neck can permanently damage the salivary glands. Chemotherapy and some newer cancer treatments can make saliva thick or reduce it for a period.
Dehydration and lifestyle
Not drinking enough fluids, heavy exercise, fever, alcohol, caffeine, smoking, vaping and cannabis can all dry the mouth.
Mouth breathing
Breathing through the mouth, because of a blocked nose, allergies, habit or snoring, dries the mouth quickly, especially overnight.
Why is dry mouth often worse at night?
Saliva flow naturally slows during sleep. On top of that, several things can make nights much drier:
- Mouth breathing or snoring, often from nasal congestion, allergies or sleeping on your back
- Sleep apnea, which is often associated with mouth breathing and loud snoring
- Medications taken in the evening, such as some sleep aids and allergy medications
- Dry indoor air, especially in Toronto winters when the heating is on
- Alcohol in the evening
Waking with a dry, sticky mouth, a sore throat or bad breath are common signs. If you or your partner notice loud snoring, pauses in breathing or gasping, mention it to your physician, as these can be signs of sleep apnea.
Remedies that help
Most people get relief from a combination of steps:
- Sip water through the day, and keep water by your bed.
- Chew sugar-free gum or suck sugar-free lozenges, ideally with xylitol, to stimulate saliva.
- Use a humidifier in the bedroom at night.
- Try saliva substitutes or moisturizing gels and sprays made for dry mouth, available at pharmacies.
- Breathe through your nose when you can, and treat nasal congestion.
- Limit caffeine and alcohol, and avoid alcohol-based mouthwashes, which dry the mouth further.
- Avoid tobacco, vaping and cannabis.
- Choose moist foods, such as soups, stews and sauces, and avoid very salty, spicy or dry foods if they sting.
- Use lip balm for cracked lips.
Ask about your medications
If you suspect a medication, do not stop it on your own. Ask your physician or pharmacist whether the dose, timing or medication could be changed. Sometimes taking a medication earlier in the day helps with dryness at night.
Medical treatment
If dry mouth is severe or caused by a condition such as Sjögren’s disease or radiation, your physician may suggest further tests or prescription treatments that stimulate saliva.
How dry mouth affects your teeth
Without enough saliva, acids stay on the teeth longer and enamel cannot repair itself as well. People with dry mouth can develop several new cavities within a short time, often along the gumline and on exposed root surfaces, even if they have rarely had cavities before. Dry mouth also increases the risk of:
- Oral thrush, a fungal infection that can cause white patches or redness and burning
- Gum irritation and sores
- Problems with dentures, including rubbing and poor fit
Protecting your teeth
- Use fluoride toothpaste twice a day. Your dentist may recommend a high-fluoride prescription toothpaste.
- Ask about fluoride varnish at your checkups.
- Clean between your teeth every day.
- Keep sugary snacks and drinks to mealtimes, and avoid sipping sweet drinks or sucking sugary candies.
- See your dentist regularly, more often if you are getting new cavities.
Our article on hydroxyapatite vs fluoride toothpaste explains why fluoride is especially important when cavity risk is high.
Choosing products when your mouth is dry
- Toothpaste: Use a fluoride toothpaste, and consider a mild, low-foaming one if regular toothpaste stings. Your dentist may prescribe a higher-fluoride toothpaste.
- Mouthwash: Choose an alcohol-free rinse. Some are made specifically for dry mouth.
- Gum and lozenges: Look for sugar-free products, ideally sweetened with xylitol, and avoid acidic or sour candies, which can wear enamel.
- Moisturizers: Gels and sprays made for dry mouth can be used before bed and during the night.
Dry mouth and dentures
Saliva helps dentures grip and protects the gums underneath. With dry mouth, dentures may rub, cause sore spots or feel loose. Keep dentures clean, take them out at night unless your dentist advises otherwise, use a moisturizing gel under them if recommended, and see your dentist if sore spots do not heal within a week or two. Our guide to dentures and daily denture care has more tips.
When to see a dentist or doctor
Book a dental visit if dry mouth lasts more than a few weeks, if you notice new cavities, sore spots or white patches, or if dentures have become uncomfortable. See your physician if dry mouth comes with dry eyes, joint pain, increased thirst and urination, unexplained weight loss or difficulty swallowing.
Dry mouth care at Regal Heights
At our St. Clair West office, we review your medications and health history at every exam, look for early signs of dry-mouth-related decay and suggest ways to protect your teeth. Learn more about our cavity prevention care, or read about dental care for seniors, where dry mouth is especially common.
Frequently asked questions
Why is my mouth dry at night?
The most common reasons are breathing through your mouth while you sleep, snoring, a blocked nose, sleep apnea, a dry bedroom and medications taken in the evening. Saliva flow also naturally drops during sleep. A humidifier, treating nasal congestion and reviewing medications can help. Loud snoring or gasping in sleep should be checked by a physician.
Which medications cause dry mouth?
Many do, including some medications for high blood pressure, depression and anxiety, allergies, pain, bladder control and sleep. The effect is often stronger when several are taken together. Never stop a medication on your own; ask your physician or pharmacist whether an alternative is possible.
Does dry mouth cause cavities?
It increases the risk. Saliva washes away food, neutralizes acid and brings minerals back to enamel. Without enough saliva, cavities can develop quickly, especially along the gumline and on exposed roots.
What is the best remedy for dry mouth?
It depends on the cause. Sipping water, sugar-free gum or lozenges with xylitol, a humidifier at night and saliva substitutes help many people. Your dentist may add high-fluoride toothpaste or fluoride varnish to protect your teeth, and your physician may review medications or treat an underlying condition.
When should I see a doctor about dry mouth?
See a physician if dry mouth lasts more than a few weeks without a clear reason, especially with dry eyes, joint pain, increased thirst, frequent urination or difficulty swallowing, which can point to a medical condition.
