Common conditions

What causes bad breath?

Reviewed by Dr. Samuel Bacon, DDS (dentist). Last reviewed November 3, 2026.

Status: Approved

Short answer: Bad breath usually starts in the mouth. Bacteria feed on leftover food and release odor, especially if brushing and flossing are skipped. Dry mouth, gum disease, certain foods, tobacco and mouth infections can also cause it. Less often, the cause is a sinus, stomach or other medical condition, so persistent bad breath is worth checking.

Common causes

The ADA notes that about half of adults have had bad breath at some point.

  • Bacteria and leftover food. Bacteria naturally live in your mouth and feed on food particles, leaving a foul-smelling waste product.
  • Dry mouth. Saliva washes the mouth. Some medications, salivary gland problems or breathing through your mouth can reduce it.
  • Gum disease. Bad breath that won't go away, or a constant bad taste, can be a warning sign of advanced gum disease.
  • Food. Garlic, onions and coffee affect the air you breathe out.
  • Tobacco. Smoking causes bad breath and raises the risk of gum disease.
  • Other health causes. Sinus conditions, reflux, diabetes, and liver or kidney disease can cause breath odor. MedlinePlus notes that a fruity breath odor can be a sign of ketoacidosis in people with diabetes, which needs medical care right away.

What helps

  • Brush twice a day and clean between your teeth every day.
  • Clean dentures daily and take them out at night.
  • Chew sugar-free gum or eat crunchy foods such as apples or carrots to get saliva flowing.
  • Stop using tobacco.
  • Use mouthwash if you like, but it only masks odor for a while. MedlinePlus notes it doesn't treat the underlying problem.

When to see a dentist

If bad breath doesn't go away with good daily care, see your dentist. Checkups can find gum disease, cavities or dry mouth. If your mouth is healthy, your dentist may refer you to your doctor.

At Indy Smile Group

At a cleaning and exam, we look for the common dental causes of bad breath, such as gum disease, decay and dry mouth, and explain what we find. Book online or call your nearest office.

Next step

Ready to talk it through with a dentist? Book online or call the office closest to you.

Frequently asked questions

Does mouthwash cure bad breath?
No. Mouthwash can mask odor and kill some bacteria for a short time, but it doesn't fix the cause.

Can bad breath be a sign of gum disease?
Yes. According to the ADA, persistent bad breath or a bad taste can be a warning sign of advanced gum disease.

When is bad breath a medical issue?
If your dentist rules out mouth causes, see your doctor. A fruity breath odor in someone with diabetes needs medical care right away.

Sources

  1. ADA MouthHealthy – Bad Breath
  2. MedlinePlus – Breath odor
  3. ADA MouthHealthy – Gum Disease

Last reviewed: November 3, 2026
Reviewed by: Dr. Samuel Bacon, DDS (dentist)

← Back to all articles