Thick, sticky saliva: why does it happen, and when does it matter?

Saliva is 99 per cent water; the remaining 1 per cent is proteins, salts and other substances. Within this small part are large proteins called mucins, which make the mouth slippery and form a protective layer over the tissues. In adults, the salivary glands produce about half a litre to one and a half litres of saliva a day. When the water part drops, the mucins stay more concentrated and the saliva takes on a stringy, sticky consistency. Thick saliva is often the other face of reduced saliva.

The nervous system also sets the consistency of saliva. The system that works during rest and digestion produces plentiful, watery saliva; this is what makes eating and swallowing easier. The system that switches on at moments of stress and danger, on the other hand, produces thicker saliva. This is why you feel your mouth go dry and sticky before a nerve-racking talk. This kind of thickening settles on its own once the stress passes.

One of the most commonly listed causes is dehydration. Drinking too little water, sweating a lot or losing fluid during an illness are among the first changes to show up in saliva. The other signs of dehydration are dark yellow, strong-smelling pee, peeing less often than usual, feeling dizzy, tiredness and headaches. Thick saliva that comes with these signs is telling you to take in fluids first.

Another common cause is breathing through the mouth. When your nose is blocked, or you sleep with your mouth open at night, the fluid inside the mouth evaporates and in the morning the saliva is thick and sticky. During a cold, sinusitis or an allergy, mucus running from the back of the nose into the throat also mixes into the saliva and makes it thicker. If a feeling of something stuck in the throat, frequently clearing your throat and a feeling of mucus running down the back of the throat come with it, the cause is usually in your nose. This picture usually clears up on its own; if it goes on for more than a few weeks, you need to see a GP.

Medicines are an important cause: more than 500 medicines are known to be able to cause a dry mouth. Medicines for anxiety and depression, some medicines used for the bladder and for COPD, allergy medicines and decongestants, some blood pressure medicines, Parkinson's medicines and chemotherapy are the main ones. Chemotherapy drugs can thicken saliva directly; radiotherapy to the head and neck also reduces saliva by affecting the glands. We have explained which medicines dry the mouth, and the general picture of a dry mouth, in detail on our dry mouth page.

Thick saliva that lasts a long time and comes with dry eyes, joint and muscle pain and extreme tiredness suggests Sjögren's syndrome. This is a condition in which the immune system affects the salivary and tear glands. For the diagnosis, blood tests, eye tests and a simple test measuring how much saliva is produced by collecting it in a container for five minutes are used; sometimes a small tissue sample is taken from the lip. Uncontrolled diabetes and some viral infections are also among the causes that reduce saliva.

A little-known consequence: thick saliva is also a risk for the salivary glands themselves. Freely flowing saliva washes bacteria away; when it thickens, this washing weakens, and bacteria can travel back up the gland's duct and inflame the gland. This inflammation most often affects the glands in front of the ear and under the jaw, and it is seen more often especially in people over 50. Painful swelling in the cheek or under the jaw, a high temperature and pus coming into the mouth suggest this picture.

A dry mouth has a particular meaning for denture wearers. An upper denture stays in place through the grip created by the thin layer of saliva between it and the palate. In a study of 86 patients, the retention of the upper denture was found to be closely linked with the secretion of the small glands in the palate; no link was found with the flow rate of the large gland in front of the ear. Of nine studies looking at dry mouth and satisfaction with dentures, six found dryness significantly linked with poorer denture performance; according to the authors, the functions most affected are speaking, chewing and retention. So it is no coincidence that your denture starts to slip as your mouth dries out.

The distinction below is not a firm diagnosis; it is a framework showing when your own measures may be enough and when you should see a doctor.

The sequence below helps you narrow down the cause behind thick saliva. The first place to go is your GP or your dentist.

1. 1

   Check for emergency signs first

   If there is swelling in the neck making it hard to breathe, or dehydration together with confusion, blue-tinged or cold skin, do not wait for the next steps; call 112. If there is painful swelling with a high temperature in the cheek or under the jaw, be examined the same day.

2. 2

   Keep an eye on your fluid intake and your pee

   For a few days, note how much water you drink during the day and the colour and frequency of your pee. Dark pee and peeing less often show dehydration; put that right first.

3. 3

   Look at the timing

   Only in the morning, or all day? Thickening that is confined to the morning suggests mouth breathing; a picture that lasts all day suggests a medicine or a general cause. Ask someone who sleeps beside you whether you sleep with your mouth open.

4. 4

   Make a list of your medicines

   Write down all the medicines you take and when you started them, and check the patient information leaflet for dry mouth as a side effect. Do not stop a medicine on your own; speak to the doctor who prescribed it.

5. 5

   Gather the symptoms that come with it

   Dry eyes, joint pain, extreme tiredness, peeing often, thirst, catarrh: tell your doctor about these. Causes such as Sjögren's syndrome and diabetes are investigated together with these symptoms.

6. 6

   Have your dentist look at your mouth

   With long-lasting dryness and thick saliva, the dentist checks for early decay, the state of the gums, signs of thrush and, if you have one, the fit of your denture. Even if the cause lies in your general health, the damage in the mouth needs following up separately.

The measures below reduce the everyday discomfort of thick saliva; if there is an underlying cause, they do not replace its treatment.

Brief thickening is harmless. A picture that lasts for weeks, on the other hand, weakens saliva's protective jobs.

When thick saliva settles depends on its cause. The framework below shows which course each cause follows.

1. Within hours

   Thickening caused by dehydration or stress settles within a short time once fluids are taken in or the stress passes.

2. Within days

   A picture caused by a cold and catarrh settles as the infection clears. If it goes on for more than a few weeks, see a GP.

3. Within weeks

   Dryness and thick saliva that do not settle within a few weeks despite home and pharmacy measures are a picture that needs a doctor. If a medicine has been changed, its effect is also seen within this time.

4. In the longer term

   With permanent causes such as Sjögren's syndrome or radiotherapy, the aim is not for the thickening to go but for the teeth, gums and denture to be protected. During this time, dental check-ups become more frequent.

Thick saliva itself needs no procedure; the scope is set by investigating the cause and by the effects it leaves in the mouth. These are the items that determine it:

Investigating the cause

Blood tests, saliva measurement and, if needed, a rheumatology assessment fall within your doctor's remit.

Treating the effects in the mouth

Decay, gum problems or a fungal infection caused by the dryness may need separate procedures.

The fit of the denture

Adjusting a denture that slips in a dry mouth, or renewing its inner surface, is a separate item.

Protective products and how often you are checked

With long-lasting dryness, moisturising products and more frequent dental check-ups become part of the yearly care.