Dry Mouth: Causes and When to See a Doctor

Dry mouth (xerostomia) is most often caused by not drinking enough, by medicines, by breathing through your mouth at night, or by anxiety. If it lasts for weeks, or comes with dry eyes, great thirst or passing a lot of urine, causes such as diabetes or Sjögren's syndrome need checking. Sipping water and sugar-free gum help. This guide is by Dr. Pedro Yelamo Vera, a GP licensed in Spain (Colegiado No. 484814280).

Why is my mouth dry?

The mouth dries out when the glands make less saliva, or when saliva dries up. The NHS lists these common causes:

• Dehydration: not drinking enough, heavy sweating, fever, vomiting or diarrhoea.
• Medicines: check the leaflet, as dry mouth is a common side effect.
• Breathing through your mouth, mostly at night, from a blocked nose or snoring.
• Anxiety and stress.
• Radiotherapy to the head and neck, or chemotherapy.
• Oral thrush.
• Less often, diabetes or Sjögren's syndrome.

Alcohol, smoking, coffee and mouthwash with alcohol also dry the mouth. In Spain you would say boca seca, and doctors write xerostomía.

Which medicines cause dry mouth?

There are many. The most common are antihistamines, antidepressants, some blood pressure medicines, water tablets, medicines for an overactive bladder, medicines for Parkinson's and strong painkillers. The effect adds up when you take several, which is common in older people. Do not stop any medicine on your own. Talk to your doctor or pharmacist.

Why is my mouth dry at night?

Usually because you breathe with your mouth open: a nose blocked by allergy or a cold, a bent nasal septum, or snoring. If you also snore loudly, stop breathing for short spells or wake up tired, it may be sleep apnoea, which is worth a check. A humidifier and treating a blocked nose help.

Can dry mouth be a sign of diabetes?

Yes. When blood sugar is high, the body loses water in the urine. The clue is dry mouth together with great thirst, passing a lot of urine, tiredness and sometimes weight loss. A blood sugar test makes it clear. Read about diabetes care.

What is Sjögren's syndrome?

It is an autoimmune condition, where the immune system attacks the glands that make saliva and tears. The classic signs are a dry mouth and dry, gritty eyes. It can also cause tiredness, joint pain, dry skin, vaginal dryness and swollen saliva glands in front of the ears. It is far more common in women, mostly after 40.

It is diagnosed with blood tests for antibodies (anti-Ro and anti-La), tests of tear and saliva flow and sometimes a small lip biopsy. A joint specialist (rheumatologist) follows it. There is no cure, but treatment eases the dryness. A gland that stays swollen should be checked.

What problems can dry mouth cause?

• Tooth decay and gum disease, because saliva protects the teeth.
• Oral thrush and mouth sores.
• Bad breath.
• Trouble swallowing, talking or wearing dentures.
• Changes in taste. For a bitter taste, read about a bitter taste in the mouth.

How can I treat dry mouth at home?

The NHS suggests:

• Sip water through the day and keep a glass by your bed.
• Suck ice or sip cold drinks with no sugar.
• Chew sugar-free gum or suck sugar-free sweets to boost saliva.
• Use lip balm.
• Brush morning and night with fluoride toothpaste and use an alcohol-free mouthwash.
• Cut down on alcohol, coffee and fizzy drinks, and stop smoking.
• Take dentures out at night.

Spanish pharmacies sell gels, sprays and lozenges that replace saliva. Ask the pharmacist for a sustituto de saliva that suits you.

When to see a doctor

• The dryness lasts more than a few weeks despite these steps.
• It is hard to talk, chew or swallow.
• You also have dry eyes, joint pain or swollen glands.
• You are very thirsty, pass a lot of urine or are losing weight.
• You think a medicine is to blame.
• You have sores, white patches, bleeding or pain in your mouth.

When to call 112

• Swelling of the tongue, lips or throat, or trouble breathing.
• Signs of severe dehydration: not passing urine, confusion, bad dizziness or great drowsiness.
• A person with diabetes who has a very dry mouth with vomiting, fast breathing or drowsiness.

Frequently asked questions about dry mouth

Getting a medical assessment

If you are in Spain and have a dry mouth, you can book a video consultation with Dr. Pedro Yelamo Vera, a physician registered in Spain. You can also read about urgent, non-emergency video care and allergies. A prescription is never guaranteed: it is issued only where clinically appropriate after a genuine evaluation, as a private electronic prescription under Spanish law. This service is for urgent, non-emergency care. In an emergency, call 112.

This guide is general information. It does not replace the package leaflet or the advice of your doctor or pharmacist.