Chronic bad breath—halitosis—can be embarrassing and frustrating. The good news? In most cases, it has a treatable cause. The majority of halitosis originates in the mouth, often from bacteria that produce sulfur compounds. Understanding the causes can help you and your dentist address it effectively. Here are the most common culprits and what to do about them.
Bacteria in the Mouth
The primary cause of bad breath is bacteria—especially those that live on the tongue, between teeth, and below the gumline. These bacteria break down food particles and dead cells, releasing volatile sulfur compounds (VSCs) that smell. Improving oral hygiene—brushing, flossing, and cleaning the tongue—can significantly reduce odor. A professional cleaning to remove tartar is also important, since tartar harbors bacteria that brushing can't reach.
Gum Disease
Gum disease creates pockets where bacteria thrive. The infection and bacteria can produce a persistent, unpleasant odor. If you have bleeding gums, redness, or have been told you have periodontal disease, treatment can improve both your gum health and your breath. Scaling and root planing (deep cleaning) removes the bacteria and tartar that contribute to the problem.
Dry Mouth
Saliva helps cleanse the mouth and neutralize acids. When saliva flow is reduced—due to medications, mouth breathing, or certain conditions—bacteria can flourish and cause bad breath. Staying hydrated, using sugar-free lozenges, or discussing saliva substitutes with your dentist or doctor can help. Addressing the cause of dry mouth is important for long-term improvement.
Food and Habits
Certain foods (garlic, onions, strong spices) can cause temporary bad breath. Smoking and tobacco use contribute to chronic odor and also increase the risk of gum disease. Reducing or eliminating tobacco can improve breath and overall oral health.
Other Causes
In a smaller percentage of cases, bad breath can stem from:
- Nasal or sinus issues — Post-nasal drip, sinus infections
- Digestive issues — GERD, stomach problems
- Tonsil stones — Calcified material in the tonsils
- Systemic conditions — Diabetes, liver or kidney disease (less common)
Your dentist can help determine whether the cause is oral or if referral to a physician is needed.
What You Can Do
- Brush twice daily, including your tongue
- Floss daily
- Stay hydrated
- Get regular dental cleanings
- If you have persistent bad breath, schedule an evaluation—don't assume it's "just how you are"
The Bottom Line
Chronic bad breath usually has a cause—and often it's treatable. Start with your dentist. A thorough exam and cleaning, combined with improved home care, can make a significant difference for most people.