Originally found on https://www.mouthhealthy.org/en/az-topics/b/bad-breath?source=promospots&content=topstories&medium=badbreath/
There are a number of reasons you might have dragon breath. While many causes are harmless, bad breath can sometimes be a sign of something more serious.
Bacteria
Bad breath can happen anytime thanks to the hundreds of types of bad breath-causing bacteria that naturally lives in your mouth. Your mouth also acts like a natural hothouse that allows these bacteria to grow. When you eat, bacteria feed on the food left in your mouth and leaves a foul-smelling waste product behind.
Dry Mouth
Feeling parched? Your mouth might not be making enough saliva. Saliva is important because it works around the clock to wash out your mouth. If you don’t have enough, your mouth isn’t being cleaned as much as it should be. Dry mouth can be caused by certain medications, salivary gland problems or by simply breathing through your mouth.
Gum Disease
Bad breath that just won’t go away or a constant bad taste in your mouth can be a warning sign of advanced gum disease, which is caused by a sticky, cavity-causing bacteria called plaque.
Food
Garlic, onions, coffee… The list of breath-offending foods is long, and what you eat affects the air you exhale.
Smoking and Tobacco
Smoking stains your teeth, gives you bad breath and puts you at risk for a host of health problems. Tobacco reduces your ability to taste foods and irritates gum tissues. Tobacco users are more likely to suffer from gum disease. Since smoking also affects your sense of smell, smokers may not be aware of how their breath smells.
Medical Conditions
Mouth infections can cause bad breath. However, if your dentist has ruled out other causes and you brush and floss every day, your bad breath could be the result of another problem, such as a sinus condition, gastric reflux, diabetes, liver or kidney disease. In this case, see your healthcare provider.