Many people misunderstand bad breath, tending to link it directly to poor oral hygiene. While bleeding gums and dental caries can certainly cause bad breath, these are far from the only causes. Other than poor oral hygiene, bad breath can show up for six different reasons.
Bad breath from the lungs
Your lungs can lend an unpleasant odor to the air you exhale in 3 ways:
⇒If your diet includes garlic, onion or other strong-smelling foods, the odor-giving chemicals in them can enter your bloodstream, make their way to your lungs and foul up the air that passes through them.
⇒ Alcohol and smoking can cause bad breath. With smoking, the tar and other substances in the smoke can cause a buildup of contaminated phlegm in your lungs. This phlegm can pass its odor to the air that you exhale. If you have alcohol in your blood from a few drinks, that smell can get on your breath in your lungs, too.
⇒ Asthma, cystic fibrosis and even lung cancer tend to leave an unpleasant stamp on the breath. Doctors are beginning to actually use smell tests to detect lung cancer at an early stage these days.