Halitosis or bad breath can be quite embarrassing, especially as people are often unaware of it until they are informed by family or friends. One way to check if you have bad breath is to lick the inside of your wrist, let it dry and then smell it. If this results in an unpleasant smell, then you probably have bad breath and you should discuss this with your dentist.
Bad breath is mainly caused by large amounts of volatile sulphur compounds (VSCs) which are produced by bacteria in the mouth. The amount of VSCs vary greatly during the day and is influenced by factors such as oral hygiene, eating, drinking and sleeping.
When oral hygiene is poor, or there is untreated periodontal disease, bacteria can incubate in the mouth and so bad breath can result. Tobacco, certain foods like garlic and onions can also influence breath, although their effect comes from the lungs rather than the mouth.