10 Causes of Bad Breath (Halitosis) You May Not Expect

Common causes of halitosis (bad breath) include poor oral hygiene, eating habits, smoking, and certain conditions and infections.

Bad breath happens when bacteria break down leftover food in your mouth, which produces smelly compounds.

Not flossing or brushing your teeth regularly can result in cavities and periodontal (gum) disease, which can cause bad breath.

Cavities

Oral bacteria that erode the enamel, or the protective covering on your teeth, cause cavities. Cavities are areas of tooth decay or surface damage.

Cavities may also trigger halitosis indirectly. “Food can get caught in the cavities,” John Grbic, DMD, a dentist at Columbia Doctors in New York, told Health. The remnants of your last meal can linger in cavities for long periods, which causes more bad breath.

Gum Disease

Bad breath is a warning sign of gum disease. Gum disease results from infections and inflammation of the gums and bone that surround your teeth.

A rare infectious disease of the gum tissue called acute necrotizing ulcerative gingivitis (ANUG) causes a strong odor.

Foods that make your breath smell bad include:

• Condiments
• Garlic
• Onions
• Pickles
• Radishes
• Spices

Bad breath from food can occasionally stem from the digestive tract. “When you digest food, the chemicals are eventually absorbed into your bloodstream and enter your lungs, where you can expel them later,” said Grbic.

Alcohol can also cause bad breath due to factors like:

• Dry mouth
• High levels of sulfur in daily drinkers
• Increase gum disease risk
• Poor oral hygiene
• Short-term effect of the smell of the alcohol itself

The keto diet is a low-carbohydrate, high-fat diet. When done correctly, it puts your body into ketosis, which allows you to burn fat and lose weight. In ketosis, you may notice keto breath, which can smell like acetone or have a fruity odor.

Fasting is another cause of bad breath. You do not produce as much saliva when you skip meals. Eating food increases the amount of saliva in your mouth.

Bad breath can sometimes be a symptom of an underlying condition or infection.

Bacterial Infections

Strep throat is a bacterial infection that causes a sore throat. According to Grbic, the bacteria may cause your breath to smell bad.

Bacterial sinus infections may also produce a smelly, pus-like mucus that causes bad breath.

Some of these infections are associated with specific types of bacteria that are known to produce a bad odor in the mouth.

Diabetic Ketoacidosis

Breath that has a sweet scent can be a sign of diabetic ketoacidosis (DKA). This life-threatening diabetes complication causes other symptoms like frequent urination, nausea, and stiff muscles.

Heartburn

Heartburn may trigger bad breath in some people. Gastroesophageal reflux disease (GERD) causes frequent heartburn due to stomach acid that leaks back into the esophagus.

A 2017 study noted that about 60% of participants with erosive tooth wear had significant GERD symptoms. Increased exposure of the teeth to stomach contents partly led to tooth decay.

Postnasal Drip

Mucus can build up in the back of your throat due to pollen allergies or a cold. The foreign particles in the postnasal drip eventually travel into your mouth and trigger bad breath.

Sjogren’s Syndrome

Sjögren’s syndrome is an autoimmune disorder that affects the glands that produce moisture. Bad breath has been associated with the condition due to dry mouth.

Long-term smoking decreases the secretion of saliva and changes its quality. Saliva helps wash away food and bacteria, which prevents bad breath.

Enzymes and antibodies from saliva can also destroy bacteria in your mouth.

It is important to clean dental appliances like dentures and fixed bridges daily. These appliances are magnets for food particles, which can become lodged in the material and lead to bad breath.

Medications that may contribute to bad breath include:

• Acid reducers
• Aminothiols
• Anticholinergics
• Antidepressants
• Antifungals
• Antihistamines and steroids
• Antispasmodics
• Chemotherapy drugs
• Dietary supplements
• Organosulfur substances

Saliva production slows down while you are sleeping. Your breath might have a bad odor until you brush your teeth after you wake up.

Mouth breathing has been associated with bad breath. According to Hadie Rifai, DDS, a dentist at the Cleveland Clinic, some people breathe through their mouths while they sleep and exercise.

Everyone has their own saliva composition made up of different bacteria, all of which affect how your breath smells.

Ways to reduce bad breath include:

• Avoid smoking.
• Chew gum regularly.
• Clean dental appliances, such as dentures, retainers, and mouthguards, daily.
• Eat more fruits and vegetables and less meat.
• Limit foods and drinks that cause bad breath.
• Maintain good oral hygiene, like brushing your teeth twice daily, cleaning your tongue, flossing, and using mouthwash.
• Visit the dentist about twice a year.

Common causes of bad breath include poor oral hygiene, eating habits, smoking, and certain conditions and infections.

Practicing good oral hygiene by brushing and flossing regularly and limiting certain foods and drinks can prevent halitosis.