There are several causes of bad breath.
Poor oral hygiene
The most common cause of bad breath is poor oral hygiene.
Bacteria that coat your teeth, tongue and gums can cause plaque (the soft white deposit that forms on the surface of the teeth), gum disease and dental decay. These bacteria combine with saliva and food in the mouth, breaking down food particles and proteins. This releases an unpleasant-smelling gas.
If you do not brush and floss your teeth regularly, any food that is trapped between your teeth will be broken down by the bacteria, causing bad breath.
These bacteria can also live in the rough surface of the tongue. Therefore, as well as brushing your teeth, cleaning your tongue can help control bad breath.
Persistent bad breath or a bad taste in your mouth can be warning sign of gum disease or tooth decay.
Any oral hygiene problems should be picked up and treated in regular check-ups with a dentist or hygienist.
Morning bad breath
Most people have bad breath when they wake up in the morning. This is normal and occurs because the mouth dries up overnight. This slows down the flow of saliva that normally washes away food particles. Bacteria quickly break down any bits of food left in the mouth, and an unpleasant, stale smell is released. The flow of saliva usually increases once you start eating.
Food and drink
Eating strongly flavoured foods, such as garlic, onions and spices, often cause your breath to smell. Strong-smelling drinks, such as alcohol and coffee, can also cause bad breath. This type of bad breath is usually temporary and can be easily avoided by not eating or drinking these types of food or drink. Good dental hygiene also helps.
Medicines
Some medication can cause bad breath. Medicines that have been associated with bad breath include:
- nitrates - sometimes used to treat angina
- some chemotherapy drugs
- phenothiazines (tranquilisers)
Talk to your GP about possible alternative medicines.
Smoking
If you smoke, your breath is likely to smell of stale smoke. As well as making your breath smell, smoking also causes staining and loss of taste and irritates your gums. This increases your risk of gum disease, another cause of bad breath. Stopping smoking will lower this risk and help prevent bad breath.
Medical conditions
Bad breath can be caused by a medical condition, although this is rare.
Dry mouth (xerostomia) is a condition that affects the flow of saliva. This can cause bacteria to build up in the mouth, leading to bad breath. Dry mouth can be caused by salivary gland problems or continually breathing through the mouth instead of the nose. As you get older, you may produce less saliva, which can lead to bad breath.
Other medical conditions that can cause bad breath include:
- infections in the lungs, throat or nose
- bronchitis
- sinusitis
- diabetes
- liver or kidney problems
- gastritis (inflammation of the lining of the stomach) and food reflux
Crash dieting, fasting and low-carbohydrate diets, such as the Atkins diet, can also cause bad breath. These cause the body to break down fat, which produces chemicals called ketones that can be smelt on the breath.
