Bad Breath: Causes, Where It Comes From and What to Do

Most of the time, bad breath comes from your own mouth: bacteria between your teeth and on your tongue, inflamed gums, cavities or dry mouth. What helps is brushing twice a day, cleaning between your teeth daily and having a dentist look for the cause if it doesn't go away. Mints and mouthwash only cover it up for a while.

The home check that gives you a clue

It's hard to smell your own breath. On top of that, the ADA notes that tobacco dulls your sense of smell, so people who smoke may not notice their own breath.

Two simple ways to find out:

• The back of your hand: put a little saliva on the back of your hand or your wrist, wait a few seconds for it to dry, and smell it. It's not a medical test; it's just a clue.
• Someone you trust: your partner or one of your kids will tell you the truth if you ask them directly.

If the answer is yes, the next step is figuring out where it's coming from.

Most of the time it starts in your mouth

As Mayo Clinic puts it, most bad breath starts in your mouth. MedlinePlus explains that bacteria that build up in your mouth and between your teeth produce the bad odor. These are the most common mouth-related causes:

• Plaque and leftover food. If you don't brush and clean between your teeth every day, plaque builds up, and food particles trapped there feed odor-causing bacteria.
• Gum disease. The NIDCR lists persistent bad breath among the symptoms of gum disease, along with red, swollen or easily bleeding gums. If that sounds familiar, read Bleeding gums when brushing.
• Cavities and abscesses. MedlinePlus lists abscessed teeth, cavities and impacted teeth among the causes.
• Your tongue. It can harbor bacteria too, as can braces that aren't cleaned well.
• Dentures that aren't cleaned well or don't fit. They can hold bacteria. The ADA recommends taking them out at night and cleaning them thoroughly before wearing them again.
• Wounds in the mouth. For example, after a tooth extraction.
• Tonsils. Tonsil stones and throat infections can also cause odor.

Food, tobacco and dry mouth

Food. Garlic, raw onions, cabbage and coffee are on MedlinePlus's list. Mayo Clinic explains that after you digest them, their compounds enter your bloodstream, reach your lungs and affect your breath; that's why the odor can linger even after you brush.

Tobacco. Smoking has its own odor, and according to the NIDCR, tobacco use is the most significant risk factor for gum disease.

Dry mouth. Saliva cleans your mouth; when you don't have enough, your mouth isn't being cleaned as much as it should be and bacteria build up. The NIDCR points out that dry mouth is not a normal part of aging: it often comes from medications (such as some for blood pressure, depression or bladder control), conditions like diabetes or Sjögren's disease, or radiation and chemotherapy. Besides bad breath, it raises your risk of cavities.

To ease it, the NIDCR suggests:

• Drinking water throughout the day and sipping it during meals.
• Chewing sugarless gum or sucking on sugarless hard candy to get saliva flowing.
• Limiting caffeine and avoiding tobacco and alcohol.
• Using a humidifier at night.

If you think a medication is drying your mouth, don't stop it on your own: talk to your doctor or dentist.

When it may come from somewhere else

If your dentist doesn't find a cause in your mouth and you brush and clean between your teeth daily, the ADA says the source may be another health problem, such as your sinuses or reflux, and you should see your doctor. These are some causes outside the mouth listed by MedlinePlus:

• Nose and sinuses: sinus infection or, in children, an object stuck in the nose. Mayo Clinic adds postnasal drip.
• Stomach and esophagus: gastroesophageal reflux disease (GERD). According to Mayo Clinic, frequent heartburn can lead to bad breath.
• Uncontrolled diabetes: diabetic ketoacidosis causes a fruity odor and can be life-threatening.
• Kidneys: kidney failure can cause an ammonia-like or "fishy" odor.
• Liver: hepatic encephalopathy, a serious complication of liver disease.
• Lungs: bronchiectasis, lung infections or abscesses.
• Some medications and supplements in large doses.

None of these can be diagnosed by smelling your breath at home. MedlinePlus recommends seeing a provider if the odor persists without an obvious cause, or if it comes with fever, cough or facial pain with nasal discharge.

What actually helps

• Brush twice a day for two minutes with fluoride toothpaste. We walk through the order in Floss, brush, rinse: the order that works.
• Clean between your teeth every day. MedlinePlus puts special emphasis on flossing; if floss is a struggle, interdental brushes and other options work too.
• Keep your mouth moist: water and sugarless gum.
• Quit tobacco. It helps your breath and your gums.
• Clean your dentures every day and keep them covered in water when you're not wearing them. More on our dentures in Miami page.
• Keep up with checkups and cleanings. The NIDCR includes routine visits with a professional cleaning in gum disease prevention.

What about mints and mouthwash? They can freshen your breath for a while, but the ADA calls them only a temporary solution, and MedlinePlus notes that mouthwash doesn't fix the underlying problem.

Tongue scraping: what the ADA says

Tongue scrapers are heavily marketed for bad breath, but the ADA says there's no evidence that brushing or scraping your tongue will prevent bad breath: the bacteria grow back just as fast. To the ADA, cleaning your tongue is a personal preference, not a necessary step.

Other sources, like Mayo Clinic, do include tongue cleaning in a daily routine. If you like how it feels, be gentle, but don't use it in place of brushing, cleaning between your teeth and finding out what's behind the odor.

What we do at your PureSmile checkup

When you come in for bad breath, we look for the cause before recommending anything:

1. We ask how long you've noticed it, what medications you take (for dry mouth), whether you smoke, and whether you wear dentures or a bridge.
2. We examine your teeth, gums, tongue and, if you have one, your denture, with X-rays when needed.
3. We explain what we see and, if needed, do a teeth cleaning or let you know if you need a deep cleaning.
4. If we don't find a cause in your mouth, we tell you plainly and recommend you see your doctor.

We see patients in English or Spanish and verify your dental insurance for free before your visit. We open on November 2, 2026 at 8000 SW 117th Ave, Suite 100, in Kendall. Join the waitlist or call us at (305) 787-3642.

Frequently asked questions

How can I tell if bad breath is coming from my stomach?

There's no home test for that. Reflux with frequent heartburn can cause bad breath, but most cases start in the mouth, so the first step is a dental exam and, if the dentist doesn't find the cause, a visit to your doctor.

How do I get rid of bad breath?

Brush twice a day with fluoride toothpaste, clean between your teeth daily, drink water, quit tobacco and clean your dentures well if you wear them. If it persists, book a checkup to look for cavities, gum problems or dry mouth.

What diseases can cause bad breath?

The most common ones are in the mouth: gum disease, cavities and abscesses. Outside the mouth, MedlinePlus lists sinus infections, reflux, uncontrolled diabetes, and kidney, liver or lung disease, among others.

How do I know if bad breath is coming from my liver?

You can't tell by the smell at home. When the liver is involved, it's a serious complication that your doctor diagnoses; if you're worried, talk to them.

Does mouthwash get rid of bad breath?

It masks it for a while but doesn't fix the cause. Therapeutic rinses can help in some cases; ask your dentist which one fits your situation.

General information; not a substitute for an in-person evaluation. Responsible dentist: Dr. Yoan Suárez Zayas, DMD (FL License DN 21413). Sources: MedlinePlus (Bad Breath; Breath odor), Mayo Clinic (Bad breath: symptoms and causes), National Institute of Dental and Craniofacial Research (NIDCR: dry mouth; gum disease) and American Dental Association (MouthHealthy: bad breath, tongue scrapers, mouthwash).