In most cases (85–90%), bad breath originates in the mouth itself. The intensity of bad breath differs during the day, due to eating certain foods (such as garlic, onions, meat, fish, and cheese), obesity, smoking, and alcohol consumption. Since the mouth is exposed to less oxygen and is inactive during the night, the odor is usually worse upon awakening ("morning breath"). Bad breath may be transient, often disappearing following eating, brushing one's teeth, flossing, or rinsing with specialized mouthwash.
Bad breath may also be persistent (chronic bad breath), which is a more serious condition, affecting some 25% of the population in varying degrees.
Contrary to the popular legend that Listerine coined the term halitosis, it actually dates from the 1870s, combining the Latin halitus, meaning 'breath', with the Greek suffix osis often used to describe a medical condition, e.g., "cirrhosis of the liver". Bad breath is not, however, a modern affliction. Records mentioning bad breath have been discovered dating to 1550 B.C. A mouthwash of wine and herbs was one recommended way of solving the problem.
Whether you call it bad breath or halitosis, it's an unpleasant condition that's cause for embarrassment. Some people with bad breath aren't even aware there's a problem.
If you're concerned about bad breath, see your dentist. He or she can help identify the cause and, if it's due to an oral condition, develop a treatment plan. In the meantime, try these helpful hints, courtesy of the American Dental Association:
What you eat affects the air you exhale. Avoid certain foods, such as garlic and onions, that contribute to objectionable breath odor. Brushing and mouthwash will only mask the odor temporarily.
Brush and floss daily so particles of food don't remain in the mouth, collecting bacteria while rotting.
Prevent dry mouth, which may be caused by various medications, salivary gland problems, or continuously breathing through the mouth. Use an artificial saliva (prescribed by your dentist), chew sugarless candy or gum, and increase your fluid intake.
Stop using tobacco products. Ask your dentist for tips on kicking the habit.
Scientists have long thought that smelling one's own breath odor is often difficult due to acclimatization, although many people with bad breath are able to detect it in others. Research has suggested that self-evaluation of halitosis is not easy because of preconceived notions of how bad we think it should be. Some people assume that they have bad breath because of bad taste (metallic, sour, fecal, etc.), however bad taste is considered a poor indicator.
For these reasons, the simplest and most effective way to know whether one has bad breath is to ask a trusted adult family member or very close friend ("confidant"). If the confidant confirms that there is a breath problem, he or she can help determine whether it is coming from the mouth or the nose, and whether a particular treatment is effective or not.
One popular home method to determine the presence of bad breath is to lick the back of the wrist, let the saliva dry for a minute or two, and smell the result. This test results in overestimation, as concluded from research, and should be avoided. A better way would be to lightly scrape the posterior back of the tongue with a plastic disposable spoon and to smell the drying residue. Home tests that use a chemical reaction to test for the presence of polyamines and sulfur compounds on tongue swabs are now available, but there are few studies showing how well they actually detect the odor. Furthermore, since breath odor changes in intensity throughout the day depending on many factors, multiple testing sessions may be necessary.