Dry mouth has various causes. Simple measures such as drinking frequent sips of water, sucking ice cubes and chewing sugar-free gum will often help. They may be all that is needed in many cases. Artificial saliva or medicine to stimulate the salivary glands is sometimes used.
What causes a dry mouth?
A dry mouth is not an illness in itself. It can have several causes. In many cases there is a problem with how the salivary glands work. The causes can include:
- Mouth breathing - which may be your usual habit, or be due to a blocked nose.
- Lack of fluid in the body (dehydration). This may occur for many reasons. For example, you may be quite ill with a high temperature or be quite frail and not drinking enough.
- Medicines. Various medicines can cause a dry mouth as a side-effect. For example:
- Tricyclic antidepressants used for low mood or pain relief.
- Antihistamines used for allergies.
- Antimuscarinic medicines used for gut problems.
- Some anti-epileptic medicines.
- Some antipsychotics used for mental health problems.
- Beta-blockers used for heart problems.
- 'Water' tablets (diuretics) used to manage blood pressure or heart problems.
- Many of these medicines cause a dry mouth by affecting the salivary glands which reduce the amount of spit (saliva) that these glands make.
- Radiotherapy to the head or neck as part of treatment for cancer. The radiotherapy can damage the salivary glands.
Sign of other illness
- Sjögren's syndrome. This is a condition which can affect various parts of the body, including:
- The joints (which can cause arthritis).
- The salivary glands (which can cause a dry mouth).
- The tear glands (which can cause dry eyes).
- HIV and AIDS.
- Alzheimer's disease.
Dry mouth at night
Some people notice a dry mouth more at night. This might be due to:
- Not routinely drinking through the night.
- People may mouth breathe more at night. This may be because they have a blocked nose and sleep with their mouth open.
- The timing of when they take their medication may mean the effects are felt more at night.
How do you treat a dry mouth?
If possible, treat any underlying cause
In some cases, it may be possible to treat the underlying cause. For example:
- If a medicine is causing the dry mouth as a side-effect, it may be possible to change to a different medicine or to reduce the dose.
- Lack of fluid in the body (dehydration), a blocked nose and anxiety can often be treated.
Whatever the cause, the following will often help:
- Take frequent sips or sprays of cold water. Always have a glass of water next to you when you go to bed.
- Suck ice cubes.
- Sugar-free chewing gum is often helpful.
- Eating pineapple chunks or partly frozen melon is often soothing and helpful.
- Some people find that it helps to suck boiled sweets. (But, sugary or acidic sweets may not be good for your teeth.)
- Consider reducing or cutting out caffeine and alcohol. They make you pass out more urine, which can be dehydrating. Caffeine occurs in tea, coffee, cola and other drinks. It is also part of some medicines.
- You can apply petroleum jelly to your lips to prevent drying and cracking.
If the above measures are not adequate then your doctor may prescribe a spray, gel or lozenge which acts as a substitute for spit (saliva). Each dose only lasts a short time and so they need to be used frequently. Some people find artificial saliva products more helpful than others.
In some cases of dry mouth, the saliva glands are only partly affected and can be stimulated to make more saliva:
- Chewing sugar-free gum can help to increase the production and flow of saliva.
- Pilocarpine is a medicine which can stimulate salivary glands to make more saliva. It may be prescribed if other measures have not helped much:
- Pilocarpine usually works well and quickly in most people with a dry mouth caused by a medication side-effect.
- Pilocarpine is not very effective in treating people whose dry mouth has been caused by radiotherapy. An operation which moves the saliva gland on one side so that it can be protected from radiotherapy is sometimes an option in these people.
- Pilocarpine can cause side-effects in some people, such as:
- Runny nose.
- Blurred vision.
- Frequent trips to pass urine.
- Side-effects tend to become less troublesome in time as your body becomes used to them. A doctor may suggest a low dose at first and that you take this for a while until any side-effects have eased. The dose may then be gradually increased with the aim of getting maximum benefit but with minimum side-effects.
- Pilocarpine should not normally be used if you have asthma, chronic obstructive pulmonary disease (COPD), a slow heart rate (bradycardia), bowel obstruction or angle-closure glaucoma.
Is a dry mouth serious?
This very much depends on the underlying cause and how that is treated.
What are the salivary glands?
The salivary glands make spit (saliva). Saliva is important in the breaking down of the food that you eat. It makes food moist, lubricating it as it passes from the mouth to the gullet. It also contains enzymes in the saliva which break down some of the starch and fat in your food.
There are three pairs of glands that make saliva. From these glands, saliva drains into the mouth down short tubes (ducts). The submandibular glands are under the floor of your mouth - one on each side - and drain saliva up into the floor of your mouth. The parotid glands lie just below and in front of your ears. Saliva passes down the parotid duct into the inside of your cheeks. The sublingual glands are just beneath your tongue.
You make small amounts of saliva all the time to keep your mouth moist. When you eat, you normally make much more saliva which pours into your mouth.
Further reading and references
Furness S, Worthington HV, Bryan G, et al; Interventions for the management of dry mouth: topical therapies. Cochrane Database Syst Rev. 2011 Dec 7(12):CD008934.
Palliative care - oral; NICE CKS, October 2018 (UK access only)
Jha N, Seikaly H, Harris J, et al; Phase III randomized study: oral pilocarpine versus submandibular salivary gland transfer protocol for the management of radiation-induced xerostomia. Head Neck. 2009 Feb31(2):234-43. doi: 10.1002/hed.20961.
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