Causes and types of bad breath

Coming from within the mouth
Most cases of bad breath come from problems within the mouth such as poor

oral hygiene or gum disease. This is discussed in more detail later in the

leaflet.

Morning bad breath
Most people have some degree of bad breath after a nights sleep. This is

normal and occurs because the mouth tends to get dry and stagnate overnight.

This usually clears when the flow of saliva increases soon after starting to

eat breakfast.

Foods, drinks and medicines
Chemicals in foods can get into the bloodstream, and then be breathed out

from the lungs. Most people are familiar with the smell of garlic, spicy

foods and alcoholic drinks on the breath of people who have recently eaten or

drunk these. Various other foods and medicines can cause a smell on the

breath. This type of bad breath is temporary and easily cured by not eating

the food. (However, some people eat spiced food every day and as a result

will constantly have a typical smell on their breath.)
If a medicine is causing the problem then discuss possible alternatives with

your doctor.

Smoking
Most non-smokers can tell if a person is a smoker by their breath which

'smells like an ashtray'. Stopping smoking is the only cure for this type of

bad breath. Smoking also increases the risk of developing gum disease,

another cause of bad breath.

Crash dieting or fasting
Can cause a 'sickly sweet smell' on the breath. This is due to chemicals

called ketones being made by the breakdown of fat. Some ketones are then

breathed out with each breath.

Medical causes
Other medical causes are uncommon. Some people with nose problems can get bad

breath. For example, a polyp in a nose, sinusitis or a 'foregin body' stuck

in a nostril (occurs most commonly in children) can cause a bad smell. In

this situation the smell tends to occur only, or more severely, when you

breathe out through your nose. It is not so noticeable when you breathe out

through your mouth. Lung or tonsil infections are sometimes a cause. Other

causes are rare.
However, in these 'medical' cases, there are usually other symptoms that

would indicate the cause. For example, a blocked nose, sinus pain, chest

symptoms, etc. If you are otherwise well and have no other symptoms apart

from bad breath, the bad smell is likely to be coming from the mouth and

other 'medical' causes are unlikely.

Bad breath coming from within the mouth
As mentioned, in most people who have bad breath the bad smell is thought to

come from bacteria within the mouth. As the bacteria break down proteins and

other debris in the mouth, they release foul smelling gases. One or more of

the following may contribute to the build up of bacteria and bad breath.

* Food stuck between teeth. Normal teeth brushing may not clear bits of

food (particularly tiny bits of meat) which can get stuck between teeth. The

food then rots and becomes riddled with bacteria. Regular flossing can clear

and prevent this problem.
* Plaque, calculus and gum disease. Dental plaque is a soft whitish

deposit that forms on the surface of teeth. It forms when bacteria combine

with food and saliva. Plaque contains many types of bacteria. Calculus,

sometimes called tartar, is hardened calcified plaque. It sticks firmly to

teeth. Gum disease means infection or inflammation of the tissues that

surround the teeth. If your gums look inflamed, or regularly bleed when you

clean your teeth, you are likely to have gum disease. The severity can range

form mild to severe.
* Coating on the back of the tongue. In some people, a 'coating' develops

on the back part of the tongue. It is not clear why this occurs. It may be

from mucus that drips down from the back of the nose ('post nasal drip'). The

coating can contain many bacteria.
* Mouth tumours that ulcerate and become infected are an uncommon cause

of bad breath.


The treatment of bad breath coming from within the mouth is good oral

hygiene.