Bad breath odors vary, depending on the cause. Some people worry too much about their breath even though they have little or no mouth odor. Others have bad breath and don't know it. Because it's hard to know how your breath smells, ask a close friend or relative to confirm if you have bad breath.

When to see a doctor

If you have bad breath, review how you keep your mouth and teeth clean. Try making lifestyle changes, such as brushing your teeth and tongue after eating, using dental floss, and drinking plenty of water.

If you still have bad breath after making changes, see your dentist. If your dentist thinks a more serious condition is causing your bad breath, you may need to see another healthcare professional to find the cause of the odor.

Most bad breath starts in your mouth. There are many possible causes, including:

• Food. The breakdown of food particles in and around your teeth can lead to more bacteria and cause a foul odor. Eating certain foods, such as onions, garlic and spices, also can cause bad breath. After you digest these foods, they enter your bloodstream, are carried to your lungs and affect your breath.
• Tobacco products. Smoking causes unpleasant mouth odor. Tobacco users also are more likely to have gum disease, which is another source of bad breath.
• Not keeping your mouth and teeth clean. If you don't brush and floss daily, food particles remain in your mouth, causing bad breath. A colorless, sticky film of bacteria called plaque forms on your teeth. If not brushed away, plaque can irritate your gums. Eventually, it can form plaque-filled pockets between your teeth and gums. The early stage of gum disease is known as gingivitis. Late-stage gum disease with bone loss is called periodontitis. Your tongue also can trap bacteria that produce odors. Dentures also can collect odor-causing bacteria and food particles, as can fixed or removable oral appliances such as braces that aren't cleaned regularly or don't fit properly.
• Dry mouth. Saliva helps cleanse your mouth, removing particles that cause bad odors. A condition called dry mouth or xerostomia (zeer-o-STOE-me-uh) can be a part of bad breath because you produce less saliva. Dry mouth naturally occurs during sleep, leading to "morning breath." It gets worse if you sleep with your mouth open. Constant dry mouth can be caused by a problem with the glands that produce saliva and by some diseases.
• Medicines. Some medicines can lead to bad breath by causing dry mouth. The body breaks down other medicines and releases chemicals that can be carried on your breath.
• Infections in your mouth. Surgical wounds after mouth surgery, such as tooth removal, as well as tooth decay, gum disease or mouth sores, can cause bad breath.
• Other mouth, nose and throat conditions. Small stones that form in the tonsils, called tonsil stones or tonsilloliths, are covered with bacteria that can cause bad breath. Infections, or constant swelling in the nose, sinuses or throat, can lead to postnasal drip. This is when fluid from your nose runs down the back of your throat. This condition also can cause bad breath.
• Other causes. Diseases such as some cancers can cause a distinctive breath odor. The same is true for disorders related to the body's process of breaking food down into energy. Constant heartburn, which is a symptom of gastroesophageal reflux disease or GERD, can lead to bad breath. A foreign body, such as a piece of food lodged in a nostril, can cause bad breath in young children.

Your risk of bad breath is higher if you eat foods known to cause bad breath, such as garlic, onions and spices. Smoking, not keeping your mouth clean and some medicines also can play a part, as can dry mouth, infections of the mouth and some diseases. In addition, other conditions such as GERD or cancer can lead to bad breath.

Your dentist likely will smell the breath from your mouth and the breath from your nose and rate the odor on a scale. Because the back of the tongue most often causes the smell, your dentist also may scrape it and rate its odor.

Some devices also can detect certain chemicals that cause bad breath. But these tools aren't always available.

To reduce bad breath, help avoid cavities and lower your risk of gum disease, regularly keep your mouth and teeth clean. Further treatment for bad breath can vary. If your dentist thinks another health condition is causing your bad breath, you likely will need to see your primary healthcare professional or a specialist.

Your dentist will work with you to help you better control bad breath caused by mouth issues. Dental measures may include:

• Mouth rinses and toothpastes. If your bad breath is due to a buildup of bacteria called plaque on your teeth, your dentist may recommend a mouth rinse that kills the bacteria. Your dentist also may recommend a toothpaste that contains an antibacterial agent to kill the bacteria that cause plaque buildup.
• Treatment of dental disease. If you have gum disease, your dentist may suggest that you see a gum specialist, known as a periodontist. Gum disease can cause gums to pull away from your teeth, leaving deep pockets that fill with odor-causing bacteria. Sometimes only professional cleaning removes these bacteria. Your dentist also might recommend replacing faulty fillings, a breeding ground for bacteria.

To reduce or prevent bad breath:

• Brush your teeth after you eat. Keep a toothbrush at work to use after eating. Brush using a fluoride-containing toothpaste at least twice a day, especially after meals. Toothpaste with antibacterial properties has been shown to reduce bad breath.
• Floss at least once a day. Proper flossing removes food particles and plaque from between your teeth, helping to control bad breath.
• Brush your tongue. Your tongue collects bacteria, so carefully brushing it may reduce odors. A tongue scraper may help people who have a coated tongue from a major overgrowth of bacteria, such as from smoking or dry mouth. Or use a toothbrush that has a built-in tongue cleaner.
• Clean bridges, dentures, retainers and mouth guards. If you wear a bridge or a denture, clean it thoroughly at least once a day or as directed by your dentist. If you have a dental retainer or mouth guard, clean it each time before you put it in your mouth. Your dentist can recommend the best cleaning product.
• Keep your mouth moist. Stay away from tobacco and drink plenty of water. Don't take in too much caffeine, spicy food or alcohol. All can dry out your mouth. Chew gum or suck on candy, preferably sugarless, to make more saliva. For constant dry mouth, your healthcare professional may prescribe an artificial saliva preparation or a medicine that you take by mouth that raises the flow of saliva.
• Change your diet. Stay away from foods such as onions and garlic that can cause bad breath. Eating a lot of sugary foods also is linked with bad breath.
• Replace your toothbrush. Change your toothbrush when it becomes frayed, about every 3 to 4 months or sooner as needed. Also, choose a soft-bristled toothbrush.
• Schedule regular dental checkups. See your dentist regularly — generally twice a year. During these checkups, your dentist can look at your teeth or dentures and clean them.

If you're going to see your dentist about bad breath, these tips can help:

• Dentists generally prefer morning appointments to test for bad breath. This lowers the chances that foods you eat during the day will affect the exam.
• Don't wear perfume, scented lotions, or scented lipstick or lip gloss to your appointment. These products could mask any odors.
• If you've taken antibiotics within the last month, check with your dentist to see if you need to reschedule your appointment.

What to expect from your dentist

Your dentist likely will start by asking about your medical history, with questions such as:

• When did you first begin to have bad breath?
• Does your bad breath occur sometimes or all the time?
• How often do you brush your teeth or clean your dentures?
• How often do you floss?
• What kinds of foods do you eat most often?
• What medicines and supplements do you take?
• What health conditions do you have?
• Do you mainly breathe through your mouth?
• Do you snore?
• Do you have allergies or sinus problems?
• What do you think might be causing your bad breath?
• Have other people noticed and commented on your bad breath?

Be ready to answer these questions so that you can make the most of your appointment time.