Having bad breath is hardly anybody's idea of fun, but most of us will suffer from it from time to time. However, if your breath smells foul for an extended period of time, and improvements in your dental hygiene regimen don't seem to help shift it, it could be a sign of a more serious medical issue.  Diseases and ailments that can cause bad breath are varied, and the following list of potential causes should by no means be considered exhaustive. If you notice chronic halitosis, you should visit either a dentist or a doctor for help with the problem, and if your dentist (such as Dr Bala Subramaniam Vasanthini B.D.S.) is worth their salt they will notice a problem during one of your routine checkups (you do visit your dentist regularly, right?).

Diabetes

Chronic bad breath is one of the most common symptoms of both type I and type II diabetes. It is also one of the most noticeable, largely because bad breath caused by diabetes has a very distinctive odour. This odour is not necessarily unpleasant, and is often described as fruity and sweet, reminiscent of pears or nail varnish remover. This smell is caused by ketones, a byproduct of the chemical reactions that occur when the body burns fat. In the case of diabetes sufferers, the body burns much higher amounts of fat than normal, due to its inability to derive sufficient energy from blood sugar. Excessive ketone levels can be quite dangerous, so the body exudes these excess ketones through the salivary glands.

Kidney disease

Like bad breath associated with diabetes, bad breath associated with kidney disease and failure has a uniquely distinctive smell - unfortunately it's a lot more unpleasant than fruity diabetes breath, and smells more like rotting fish or even stale urine.This deeply unpleasant smell is causes by excessive build up of ammonia. Ammonia is usually filtered out of the body by the kidneys and expelled via urination, but once kidneys begin to fail the ammonia they can no longer filter enters the bloodstream, and can also build up in the lungs and salivary glands, causing halitosis

Cancer

It's pretty alarmist to immediately associate bad breath with cancer, but incurable bad breath can be one of the very first signs of cancerous growth, and catching any cancer early vastly improves your chances of successfully fighting it. Unfortunately, halitosis caused by cancer lacks the distinctive smell of halitosis caused by kidney disease or diabetes. As a general rule, there are three types of cancer that cause bad breath:

• Gastric cancer: This cancer develops in the lining of the stomach. The same bacteria that causes stomach ulcers (helicobacter pylori) can also provoke stomach cancer, so if you suffer from both bad breath and stomach ulcers you should urgently seek medical help. 
• Lung cancer: You should pay particular attention to your breath if you are a smoker, as the pungent aroma of cigarette smoke on your breath can mask genuine halitosis. Other early warning signs of lung cancer include coughing, shortness of breath and unexplained weight loss.
• Mouth cancer: Another cancer that is often caused by smoking, early signs of mouth cancer besides bad breath can include enlarged lymph nodes, discoloured patches on the lining of the mouth, and mouth ulcers that heal slowly or not at all.