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Is your bad breath a sign of serious illness? A dentist shares how to tell

Bad breath stinks, literally, but it may also be a sign of a serious health problem. A dentist discusses the different types and causes of halitosis.
/ Source: TODAY

Bad breath happens to everyone from time to time. That's why there are so many gums, mints and mouthwashes advertised to get rid of it fast.

Halitosis (the medical term for bad breath) is usually caused by something in the mouth — whether it's leftover bits of food stuck in the teeth, a buildup of bacteria on the tongue or smoking cigarettes. Even a meal packed with garlic and onion can be smelled on the breath long after it's been digested.

Is bad breath a sign of serious illness?

Most cases of halitosis are temporary and treatable, but sometimes bad breath can be a symptom of a more serious illess, according to Dr. Kami Hoss, dentist and author of “If Your Mouth Could Talk: An In-Depth Guide to Oral Health and Its Impact on Your Entire Life."

“Your mouth is the opening to your body. ... It's a reflection of not only what is happening not only in the mouth itself, but also what’s happening in the other parts of the body,” Hoss tells

Systemic health issues, organ dysfunction and other conditions can cause bad or unusual-smelling breath, he adds.

What usually causes bad breath?

The most common cause of bad breath is poor oral hygiene. "Our mouth is filled with millions of microbes, and these make up our oral microbiome," says Hoss. This includes good bacteria, which help keep our mouth healthy and aid digestion, as well as bad bacteria.

“In a healthy mouth, there’s a balance,” says Hoss, adding that proper oral hygiene should cut down on the bad bacteria while allowing a healthy level of good bacteria.

If the mouth and teeth are not cleaned regularly, the harmful bacteria (along with food debris) can build up and produce a foul odor, Hoss explains. It may smell sulfuric or like rotten eggs.

How to tell if you have bad breath

Bad breath isn't always obvious to the breather, says Hoss. Despite the close proximity of the nose to the mouth, it's hard to tell how our breath smells because we get so used to it from breathing, he explains.

When a person has halitosis, they may not be aware at all, he adds — it might even be pointed out by a partner, friend or colleague, which is uncomfortable for all parties involved.

The classic trick — exhaling into a cupped hand and taking a whiff — is not that effective, Hoss says. The best way to smell your own breath is to lick the back of your hand and wait a few seconds or until the saliva dries. “Then smell it, and that’s how your mouth smells,” says Hoss.

How to treat bad breath

If you have bad breath, the first line of defense is good oral hygiene, Hoss explains. "You want to eliminate all the things that are potentially causing it from an oral health issue," says Hoss. That means brushing and flossing every morning and night, scraping or cleaning the tongue daily and using an alkaline mouthwash.

Alcohol-based or antimicrobial mouthwashes should be avoided because they can dry out the mouth out and kill good bacteria, Hoss adds. Routine dental cleanings and checkups are also important to stay on top of your oral health.

How do you know if your bad breath is serious?

Can be a symptom of an underlying medical problem? Yes.

"If you're doing all that and it's not getting resolved, then you have to look deeper and see if you have other serious health issues going on," says Hoss. In some cases, oral hygiene alone won’t cut it because it’s not treating the root cause, he adds.

When bad breath becomes chronic and you've ruled out anything else going on with the mouth, it's time to see a doctor, says Hoss.

It's also important to take note of how your breath smells and any other symptoms. Certain conditions can cause distinct types of bad breath or specific odors, says Hoss. Here are some examples:

What illnesses give you bad breath?


People who are diabetic or pre-diabetic may experience a peculiar smelling breath: Think fruit or nail polish remover, Hoss explains.

"The body, because of the lack of insulin, can't burn sugar, so it starts burning fat instead and produces these chemicals called ketones," says Hoss. When blood sugar levels aren't managed, ketones can build up and reach high levels in the blood. The result is a breath that smells fruity or like acetone (the main ingredient in nail polish remover), because acetone is a ketone, says Hoss.

Fruity-smelling breath can also be a sign of diabetic ketoacidosis, a life-threatening complication that occurs when ketone levels are so high that the blood becomes acidic, according to the National Library of Medicine — it's often a sign of Type 1 diabetes before a person is diagnosed.

Acid reflux

Sometimes, bad breath can be caused by an issue bubbling up from the stomach. Acid reflux or gastroesophageal reflux, occurs when acid in the stomach flows back up the esophagus, says Hoss.

Acid reflux can happen to anyone, but the more severe and chronic form is called gastroesophageal reflux disease or GERD — which affects an estimated 20% of the U.S. population.

"Just imagine all that acid and all the food that’s hasn’t been digested yet, it just gets pushed up your esophagus and in your mouth," says Hoss. This can cause the breath to have a sour, pungent odor and smell like the undigested food in your stomach.

Kidney problems

“If your kidneys aren’t functioning correctly, they can’t filter out certain minerals out of your blood properly,” says Hoss. The kidneys work to remove toxins and other waste products from the blood, which are then excreted in your urine, per the Cleveland Clinic.

When a person has kidney problems or kidney disease, these toxins build up in the body and circulate in the bloodstream, says Hoss. “This can make your breath smell like ammonia or urine,” he adds. Ammonia is found in many household cleaners.

Liver disease

You may be able to smell liver issues or liver disease on your breath.

“When your liver isn’t working properly, it can’t filter toxins from the blood or regulate your blood sugar,” says Hoss. As a result, these toxins remain in the body and can cause the breath to smell overly sweet and musty, Hoss adds.

In severe cases of liver disease, the breath may smell strongly of rotten eggs (called fetor hepaticus), according to the National Institutes of Health.

Bacterial or viral infections

Any infection in the mouth, nose, sinuses or throat can cause the bad breath, Hoss explains. This includes localized infections, such as an infected wound, surgical site or dental abscess.

Can a virus cause bad breath?

An infection from a virus or bacteria, like bronchitis, tonsillitis and sinusitis, can cause inflammation and a buildup of mucus in the back of the throat, also called post-nasal drip, says Hoss. The mucus may have a foul or rotten odor and taste, which results in bad breath.

Post-nasal drip is often worse while sleeping, Hoss explains, so people may notice that mornings are more intense, breath-wise.

Pneumonia can cause a buildup of fluid in the lungs which may smell foul and cause bad breath when coughed up, Hoss adds.

In these cases, the bad breath may be accompanied by symptoms of the underlying infection like congestion, coughing, pain or a fever.


"Saliva is really, really important. ... It helps with all sorts of things — digestion, lubrication when swallowing and ... cleansing of your mouth," says Hoss, adding that saliva also keeps the mouth's pH level balanced.

When the mouth doesn't produce enough saliva, harmful bacteria can quickly build up and start producing odors, Hoss explains. The bad breath may be accompanied by a feeling of dryness or stickiness and thick saliva in the mouth.

Dry mouth (also called xerostomia) can be caused by dehydration, says Hoss, which reduces saliva production. Drinking enough water is a key part of maintaining oral health and preventing bad breath.

Certain health conditions can also dry out the mouth, Hoss adds. These include issues affecting the salivary glands, diabetes, stroke, Alzheimer’s and autoimmune disorders (such as Sjogren’s syndrome or HIV/AIDs), per the Mayo Clinic.


"There are hundreds of medications that can cause dry mouth and reduction in saliva. It's a very common side effect," says Hoss. Some medications can also release chemicals that can be smelled on the breath, he adds.

Medications commonly linked to bad breath include antihistamines, antidepressants and cancer treatments, such as chemotherapy and radiation. Even stress can cause dry mouth, says Hoss.

Always consult your doctor if you have any questions, says Hoss, or check the listed side effects of a medication if you are concerned about dry mouth.