What causes the common cold? A group of viruses. What's behind stomach ulcers? A single strain of bacteria. What causes tetanus? A single species of microbe (not rust, as you might expect). And bad breath? In all, halitosis probably has more than 100 causes: oral bacteria, dental plaque, tartar, gingivitis, periodontal disease, dry mouth, nasal allergies, alcohol, tonsil stones, coffee, garlic, smoking, mouth breathing and much, much more.
As you can see, the origins of oral odor are... complicated. In fact, you'd be hard-pressed to find a health condition that has more (or more varied) causes.
In the interests of full coverage, here's a lexicon -- but by no means comprehensive one -- list of the causes of bad breath, both rare and common. Some of these problems have even appeared in the news recently.
Alcohol: It's not just beer, wine or spirits that can give you major dragon breath. In fact, a common cause of halitosis may be hidden in one of the products you use to clean your palate: mouthwash. Take a gander at the label of any cheap, non-specialty rinse, and you'll see alcohol listed among the inactive ingredients (often at 40 percent concentration). This amount of alcohol can parch your palate in seconds, leaving you open to halitosis. It's a bit ironic, really. After all, it's not even an active ingredient. All it does is give you bad breath. You'd do no worse to gargle with 80-proof vodka.
Allergies: Nasal allergies cause post-nasal drip, an uncomfortable condition that causes mucus to trickle down the back of the throat. You'll know you have it if you're coughing, sneezing and stinking. And the environmental allergens that cause post-nasal drip aren't going away. Recently, CBS Chicago recorded a tree pollen count so high that it qualified for a "dangerous air warning."
Bacteria: These are the underlying cause of almost all forms of halitosis, since they emit stinky compounds that give bad breath its putrid whiff. To eliminate microbes, try rinsing with an alcohol-free specialty breath freshening mouthwash.
Coffee: Americans drink 146 billion cups of coffee per year, according to the 2012 Coffee Statistics Report. That's a lot of bad breath. Oral health expert Steven Sulfaro recently told the Tri-County Times that sidestepping coffee breath takes patience: "It takes diligent home care with twice a day brushing and flossing, especially after drinking tea or coffee." What causes coffee breath? According to a report in the Journal of Breath Research, the main offender is a molecule called 3-mercapto-3-methylbutylformate, which smells like old fish, expired milk and rotten eggs' "musty" aroma. Hoo-whee.
Garlic: Is there a more notorious cause of halitosis? Garlic recently made headlines, not for leading to oral odor (that's obvious enough), but for defeating the latest herbal treatment thrown at it. A study published in the Journal of Agricultural Science found that a Chinese herb, Houttuynia cordata, is all right at masking the smell of garlic breath for a little while. However, the alternative remedy did nothing to actually eliminate the odor. Bummer.
Gum disease: Even mild gingivitis can give off a bad odor, which makes regular brushing and flossing a must.
Mouth breathing: This one most commonly occurs at night, when you can't help but sleep with your yap hanging wide open. You tongue dries out, bacteria run wild and you wake up with raging morning breath. Use a specialty lozenge or mint the moment you get up as a way to moisten your mouth. Sleeping next to a humidifier also seems to help.
Periodontal disease: This is a serious oral condition, one that's sort of like gingivitis' bigger, scarier cousin. It starts with simple gum disease. However, over time, the dental plaque and bacterial colonies that irritate the gums gradually migrate down the roots of your teeth. These eventually reach the bone bed. Your teeth rot and loosen, your gums turn bright red and pull away from your teeth, and your breath absolutely reeks. This is periodontal disease. Ultimately, it can cause tooth loss, not to mention boosting the risk of pregnancy complications and heart disease. Treating periodontal disease is critical, since reducing the severity of the condition can improve breath odor and oral health. According to a new report, it can even predispose people with diabetes to lower medical costs.
Smoking: It causes bad breath, gum disease, tooth decay and cancer. That's why the Centers for Disease Control and Prevention recommends quitting. In fact, following the debut of its latest anti-smoking campaign, Tips from Former Smokers, calls to its 1-800-QUIT-NOW hotline quickly doubled.
Tonsil stones: These little nuggets of protein and bacteria accumulate on your tonsils. If you've ever coughed one up, you know that they may be the most potent cause of oral odor on earth.
So many causes, and yet we've only just begun! To learn about a few more, check out this short review.
For more by Dr. Harold Katz, click here.
For more on dental health, click here.
HuffPost Lifestyle is a daily newsletter that will make you happier and healthier — one email at a time. Learn more