Bad breath, medically known as halitosis, can result for many reasons. The main reason being poor oral hygiene but it may also be a sign of other health problems. Bad breath can be made worse by the types of food we eat or unhealthy lifestyle habits.   

Basically, all the food we eat is broken down in the mouth. As foods are digested and absorbed into the bloodstream, they are carried to your lungs and given off in your breath. If you eat foods with strong odors such as onions or garlic , brushing, flossing even mouthwash merely covers up the odor. The odor will not go away completely until the food has passed through the body. 

If you do not brush and floss your teeth daily, food particles can remain in your mouth, promoting bacterial growth between teeth, around gums and on the tongue. This is a main cause of bad breath. Antibacterial mouthwashes can help to reduce bacteria. In addition, odor causing bacteria and food particles can cause bad breath if dentures are not properly cleaned. 

Smoking or chewing tobacco based products can not only cause bad breath, stain teeth, irritate the gums and also reduce your ability to taste foods. Persistent bad breath or a bad taste in the mouth way be a warning sign of gum disease which is caused by the buildup of plaque on teeth. Bacteria cause the formation of toxins to form, which irritate the gums. If gum disease continues and is left untreated, it can cause damage to the gums and jawbone.

A medical condition known as dry mouth can also result in bad breath. Saliva is necessary to moisten the mouth, neautralise acids which produce plaque, and wash away dead cells that accumulate on the tongue, gums and cheeks. If not removed these cells decompose and can cause bad breath. Dry mouth may be a side effect of various medications, salivary gland problems, or continuous bad breath through the mouth. 

Other causes of bad breath include poorly fitting dental appliances, yeast infections of the mouth, and dental cavities. Many other diseases and illnesses can cause bad breath such as respiratory tract infections such as pneumonia, bronchitis, chronic sinus infections, postnasal drip, diabetes, chronic acid reflux, liver or kidney problems.