Written by Calvin Bennet · Updated September 2026
Bad breath (halitosis) is usually caused by odor-producing bacteria in your mouth — most often from a coated tongue, poor oral hygiene, or dry mouth. It is very common (about half of adults have had it), and it is usually fixable with better daily cleaning, tongue cleaning, hydration, and regular dental visits. Persistent bad breath can be a sign of gum disease, so it is worth a dentist’s look. Below are the five most common causes — followed by exactly how to get rid of it.
Bad breath, or halitosis, is an unpleasant smell that often comes from the mouth. It can be caused by a variety of things including certain foods, dental problems, and medications. In some cases, bad breath may be a sign of a serious health condition. Here are the five most common reasons you could be struggling with bad breath.
1. Oral Hygiene
The most common cause of bad breath is unsurprisingly poor oral hygiene. If you are not brushing properly at least twice a day, this is going to lead to food and bacteria buildup, causing your breath to smell. A good mouthwash, as well as remembering to floss, are also effective additions to your routine to ensure you’re cleaning as thoroughly as possible. Periodontal, or gum, disease usually results due to poor hygiene and can lead to bad breath as well. Alongside your daily routine it is important to have regular dental cleanings to keep your oral health in the best possible shape.
2. Diet
The foods and drinks you consume can affect the smell of your breath beyond just inside your mouth. Highly potent foods such as garlic or onions contain odor-causing particles that enter your bloodstream, which leads to your lungs. So, even if you are brushing afterward, when you exhale, your breath can still be altered by the food. If you have a diet that is high in sugar, the bacteria that feed on the sugars can cause poor-smelling breath. If you eat a high-protein or low-carb diet, your body may release sulfurous gasses due to the difficulty of breaking down the proteins. Other common culprits of bad breath include coffee and alcohol. Each of these reduces saliva production, which leaves more room for bacteria to grow, leading to worse breath.
3. Smoking
Aside from causing many other health problems such as cancer, heart disease, and lung disease, smoking affects your breath as well. This is because of the smell left behind in your throat and lungs from the smoke. Chemical compounds are also left behind, mixing with saliva to cause your breath odor to worsen. Any tobacco-based product can cause bad breath, as well as whatever device from which you are smoking..
4. Digestion
Digestive issues such as constipation, bowel problems, and poor digestion often cause acid reflux. Acid reflux is when the muscle at the bottom of your esophagus relaxes at the wrong time, leading to stomach acid coming back up through your esophagus. This allows the odors from your food and drinks to come back up as well. Constant acid reflux can lead to a slew of other health concerns such as esophagitis, ulcers, or esophageal cancers.
5. Other Medical Concerns
Besides gum disease from plaque buildup, other medical concerns can cause bad breath as well. Mouth yeast infections, as well as cavities, can cause poor-smelling breath. The medical condition known as dry mouth, or xerostomia, can also cause this issue. Without the necessary amount of saliva, cells decompose in the mouth instead of being washed away. If none of the 1-4 causes mentioned in this article are causing your bad breath, it could be a more concerning medical problem such as:
- Allergies
- Infections such as pneumonia or bronchitis
- Sinus infections
- Diabetes
- Gastrointestinal issues
- Lung infection
- Liver or kidney problems
Understanding the causes of bad breath can help you take steps to improve your oral hygiene to reduce or eliminate the problem. If you have persistent bad breath that doesn’t seem to be related to any of these common causes, it’s a good idea to see your dentist or doctor to rule out other possible health problems.
How to Get Rid of Bad Breath
Once you know the cause, the fixes are mostly simple daily habits:
- Brush twice a day for two minutes with fluoride toothpaste.
- Floss daily (or use a water flosser) to clear the food and plaque your brush misses.
- Clean your tongue with a scraper or your brush — the back of the tongue is where most odor bacteria live.
- Stay hydrated and chew sugar-free gum (look for the ADA Seal) to keep saliva flowing and rinse bacteria away.
- Use an antibacterial mouthwash with the ADA Seal as a supplement — not a substitute — for brushing and flossing.
- See your dentist regularly for cleanings, and sooner if bad breath persists despite good care.
Do Not Forget Your Tongue
If there is one thing most people miss, it is the tongue. Brushing your teeth alone leaves the bacterial coating on the back of the tongue untouched — which is why so many people still have bad breath even right after brushing. Adding a quick tongue clean to your routine is often the fastest improvement you can make.
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Frequently Asked Questions
What is the main cause of bad breath?
Odor-producing bacteria in the mouth – especially the coating on the back of the tongue – along with poor oral hygiene, gum disease, and dry mouth. Certain foods, smoking, and some medical conditions also contribute.
How do I get rid of bad breath permanently?
Treat the cause, not just the smell: brush twice a day with fluoride toothpaste, floss daily, clean your tongue, stay hydrated, and keep up regular dental cleanings. If it persists, see your dentist.
Can bad breath be a sign of something serious?
Usually it is caused by oral factors. But persistent bad breath can signal gum disease or, less often, issues like sinus infections, acid reflux, or other conditions – so see a dentist or doctor if good oral care does not fix it.