Halitosis is also referred to as oral malodor, but most of us know it quite simply as "bad breath." Even though it's a comparatively minor health problem, bad breath can be distressing and a bit of a social handicap. It is not a wonder that we spend millions each year on efforts to freshen our breath with various gums, sprays, and mouthwashes.

The most common cause of bad breath is the food you eat. Garlic, onions, some kinds of fish, and diets rich in fat and meat can all result in halitosis. Saliva and bacteria naturally occurring in your mouth break down small pieces of food that are caught between your teeth. This releases volatile substances or chemicals that lead to bad breath.

The breakdown products of proteins in the body used for energy are exhaled through the lungs, and therefore missing meals, hunger, fasting, starvation, and low-calorie diets can also cause bad smelling "hunger breath."

Because there is no flow of saliva during sleep, putrefaction (decomposition or rotting) of saliva and debris in the mouth can lead to bad breath in the morning.

Halitosis is also caused by:

• poor oral hygiene (not brushing or flossing regularly)
• smoking
• alcohol
• dentures
• dry mouth
• periodontal or gum disease that causes teeth to become loose, thereby creating pockets in the gums that harbour bacteria and lead to bad breath
• chronic lung or sinus infections
• breathing through your mouth because of enlarged tonsils or adenoids
• mouth infections such as thrush (candidiasis)
• systemic diseases such as diabetes, liver disease, or kidney disorders
• pregnancy
• a change in the acidity of saliva

Taking certain medications can also cause bad breath, especially those that reduce the flow of saliva and dry out the mouth (e.g., some antidepressants, antipsychotics, antihistamines, decongestants, and medications to reduce high blood pressure).

The awkward irony of halitosis is that many people aren't aware that they have it. This is because the cells in the nose that are responsible for the sense of smell actually become unresponsive to the continuous stream of bad odour. If you have bad breath, you may need to be told, or you may notice the negative reaction of other people when you're just too close!

It's easy to self-diagnose bad breath. You can lick your wrist, let it dry for a few seconds and smell the area, or cup your hands over your mouth and sniff your own breath. If you need a second opinion, ask a friend, family member, or your physician or dentist.