Head-and-shoulders photo of an African American woman holding her hands over her mouth; for information about bad breath and teeth whitening from Plano, TX dentist Dr. Miranda Lacy.

9 Causes of Bad Breath and Why Hiding the Odor Isn’t Good Enough

I have a bad smell in my mouth. I brush daily but it still smells. I chew gum all day long and suck on mints, but I don’t want to get cavities from all the sugar. Any suggestions? Will teeth whitening help? – Thanks. Luca from San Antonio

Luca – Many factors can affect the way your breath smells. Although teeth whitening products can brighten your smile, they won’t help your breath smell fresh.

What Causes Bad Breath?

Several factors are reviewed below.

1. Bacteria

Bacteria in your mouth is the most common cause of bad breath. In addition to brushing your teeth daily, floss between them. Flossing removes food debris that promotes bacteria. If bacteria get stuck between your teeth, it will begin to smell bad. Some people benefit from a tongue cleaner to remove bacteria. Others gently brush their tongue.

2. Gum Disease

Infected gum tissue breeds bacteria. Gums can get inflamed and pus-filled and cause a foul odor on your breath.

3. Dry Mouth

Saliva cleanses your mouth. Lack of saliva production causes bacteria to breed and make your breath smell bad. Breathing through your mouth, instead of your nose, will also decrease saliva production.


When stomach acid flows up your esophagus, gastroesophageal reflux disease (GERD) occurs. The backup of regurgitated food can cause your breath to smell bad.

5. Liver Disease

Your liver removes toxins from your body. If your liver isn’t functioning properly, toxins can build up in your bloodstream and cause a sweet, musty odor on your breath.

6. Kidney Disease

Malfunctioning kidneys cause minerals to collect in your bloodstream. The result is often a metallic taste in your mouth and breath that smells like ammonia.

7. Extreme Low-Carb Diet

If you’re on an extremely low-carb diet, your body will burn fat, instead of sugar. Fat burning releases ketones in your body, including acetone, which can make your breath smell like nail polish.

8. Pneumonia

Phlegm from the bacterial or viral infection in your lung has a bad odor. As you cough it up, it will affect the smell of your breath.

9. Bronchitis

As you cough, foul-smelling mucus from your lungs will make your breath smell bad, too.

There are powerful products to help you treat bad breath, including BreathRx. But don’t neglect an appointment with your dentist or medical doctor to identify the cause of the problem. You might have an underlying medical condition that needs to be treated. The odor of your breath can be a lifesaving sign of something more serious. Don’t ignore it.

Plano, TX dentist Miranda Lacy sponsors this post.