Known as halitosis, bad breath has an unpleasant odor. This odor can strike at times or be persistent, depending on the cause. For many, the millions of bacteria that live in the mouth ; especially  on the back of the tongue are the primary causes of bad breath. The mouth's warm, moist conditions make an ideal environment for these bacteria to grow. Most bad breath is the result of poor oral hygiene.

Some types of bad breath, such as "morning mouth," are considered to be fairly normal, and they usually are not health concerns. The morning bad breath occurs because the saliva that regularly washes away decaying food and odors during the daytime diminishes at night while you sleep. Your mouth becomes dry, and dead cells adhere to your tongue and to the inside of your cheeks. Bacteria use these cells for food and expel compounds that have a foul odor.

Causes of Bad breath

Poor oral hygiene

 Improper brushing and lack of flossing can leave food particles to decay inside the mouth.
 

Infections in the mouth

Periodontal (gum) disease, Respiratory tract infections,  Throat infections, sinus infections, lung infections.
 

External agents

Garlic, onions, coffee, cigarette smoking, chewing tobacco etc.
 

Dry mouth (xerostomia)

This can be caused by salivary gland problems, medications or by breathing through the mouth.
 

Systemic illnesses:

 Diabetes, liver disease, kidney disease, lung disease, sinus disease, acid reflux disease etc.
 

Psychiatric illness:

Some people may imagine that they have bad breath, but it is not noticed by oral-health-care professionals or others. This is referred to as "pseudo halitosis."

You can control your bad breath

Cover up the odor:

 Make it a habit to always chew on something nicely scented; like gum or candy so that it masks your bad breath. Make sure it's sugar free, or else the sugar can promote tooth decay.
 

Make it a habit to use mouthwash every time you use the bathroom:

 Drink plenty of water throughout the day. It will clear out and cover the bad breath, at least temporarily.
 

Respect personal space:

When you're talking to someone, they shouldn't be able to smell your breath, unless it is quite powerful. If they can smell your breath, you're probably too close.
 

Brush your tongue and your teeth thoroughly:

 You may as well run the brush over the insides of your cheeks while you're at it. Over 50% of what causes bad breath is not on your teeth.
 

Floss before you brush:

 If you floss before you brush, you'll be able to smell how bad your breath smells and see how your toothbrush is cleaning your teeth.
 

Keep Your Mouth Moisturized:

 You could have heard this many times but a dry mouth is a stinky mouth. Drink a lot of liquids.

Diagnosis

Your dentist will review your medical history for medical conditions that can cause bad breath and for medications that can cause dry mouth. Your dentist also will ask you about your diet, personal habits like smoking, chewing tobacco and any symptoms, including when the bad breath was noticed and by whom.

You will need diagnostic tests if the doctor suspects a lung infection, diabetes, kidney disease, liver disease or Jorgen’s syndrome. Depending on the suspected illness, these tests may include blood tests, urine tests, X-rays of the chest or sinuses, or other specialized diagnosis.