Bad breath is a relatively common symptom that can appear after consuming foods such as broccoli, garlic or onion, or by going without eating for many hours, but it can also appear due to the accumulation of bacteria on the tongue, cavities or gum problems, such as gingivitis or periodontitis.
Bad breath, known scientifically as halitosis, can also be accompanied by other symptoms, such as a feeling of dry mouth, increased thirst, general malaise, tiredness or anxiety, which may indicate a health problem, such as diabetes, kidney failure or psychiatric problems, for example.
It is important to consult a general practitioner or dentist whenever symptoms of bad breath appear, especially when it is frequent or accompanied by other symptoms, so that an assessment can be carried out, the cause can be identified and the most appropriate treatment can be indicated.

The main causes of bad breath are:
1. Dirt on the tongue
Most of the time, bad breath is caused by the accumulation of bacteria on the tongue that leaves its surface a whitish, yellowish, brown or gray color. More than 70% of people with bad breath, by cleaning their tongue properly, achieve pure breath.
What to do: Whenever you brush your teeth, you should also use a tongue cleaner that you can buy in pharmacies or drugstores. To use, simply press across the tongue, from back to front, to completely remove dirt from the tongue. If you don’t have a cleanser, you can also clean your tongue with a toothbrush, moving from back to front at the end of brushing.
2. Cavities
Cavities are also common causes of bad breath because in this case the proliferation of bacteria inside the mouth is very large and there is a release of a characteristic smell that leads to the development of bad breath.
What to do: If any of these problems are suspected, you should go to the dentist to identify and treat each one. Furthermore, it is important to brush your teeth, gums, the inside of your cheeks and your tongue very well to avoid the appearance of new cavities or bacterial plaque. See how to brush your teeth correctly.
3. Gum or periodontal disease
Gum or periodontal diseases, such as acute necrotizing ulcerative gingivitis, herpetic gingivitis, periodontitis, pericoronitis, periodontal abscess, can cause bad breath, as they cause inflammation and infection in the gums.
These diseases are caused by the accumulation of plaque or tartar between the teeth and gums, resulting in inflammation, infection or destruction of the tissue that supports the tooth, which may affect one or more teeth.
What to do: You should consult your dentist for an evaluation and diagnosis of gingivitis or periodontitis. The dentist must completely remove all accumulated tartar, and it is important to brush your teeth correctly, with a soft or electric toothbrush and use dental floss daily. Furthermore, in the case of periodontitis, the dentist may recommend the use of antibiotics or even surgery. See how periodontitis is treated.
4. Going for many hours without eating
When you spend more than 5 hours without eating anything, it is normal to have bad breath, which is why when you wake up in the morning this odor is always present. This happens because the salivary glands produce less saliva, which is used to help digest food and keep the mouth clean.
Furthermore, when you go without eating for a long time, the body can begin to produce ketone bodies as a source of energy from the breakdown of fat cells, causing bad breath.
What to do: It is recommended to avoid going more than 3 or 4 hours without eating during the day, and even if you need to fast for longer, you should always drink small sips of water to clean your mouth and stimulate saliva production. Sucking on a clove can be a very effective natural solution in this case.
5. Wear dentures
People who wear some type of denture are more likely to have bad breath because it is more difficult to keep their mouth clean and the plate itself can accumulate dirt and food debris, especially if it is not the ideal size, with a perfect fit inside the mouth. .
Small spaces between plaque and gums can allow food debris to accumulate, causing bacteria to multiply, causing bad breath.
What to do: You should brush your teeth and the entire area inside your mouth and also clean your dentures very well every day before going to sleep. There are solutions that the dentist can recommend to leave the dentures to soak overnight and eliminate bacteria. But before putting this prosthesis back into your mouth, in the morning, it is also recommended to wash your mouth again to keep your breath clean. Check out the step-by-step guide to clean your dentures correctly.
6. Eating foods that make your breath worse
Certain foods can cause bad breath, such as broccoli, kale and cauliflower. These vegetables encourage the formation of sulfur within the body and this gas can be eliminated through the anus or mouth.
Furthermore, foods such as garlic and onions also promote bad breath just by chewing them because they contain a very strong and characteristic odor that can remain in the mouth for hours.
What to do: The ideal is to avoid consuming these foods too frequently, but in addition it is also important to always brush your teeth and clean your mouth very well after consuming them because this way your breath becomes fresher again. See the complete list of foods that cause gas and, therefore, also promote bad breath.
7. Throat or sinus infections
When you have a sore throat and have pus in your throat, or when you have sinusitis, it is normal to have bad breath because in this case there are many bacteria in the mouth and nasal cavity that end up releasing this bad smell.
What to do: Gargling with warm salt water is excellent for helping to remove pus from the throat, naturally eliminating bad breath. Breathing the steam of warm water with eucalyptus is also excellent for fluidizing nasal secretions, encouraging their removal, making it a great home remedy for sinusitis. Furthermore, it is important to consult an otorhinolaryngologist, who may recommend the use of antibiotics to combat the infection.
8. Stomach problems
In case of poor digestion or gastritis, eructation, which is burping, is common. These gases, when passing through the esophagus and reaching the mouth, can also cause bad breath, especially if they are very frequent.
What to do: improve digestion by always eating in small quantities, in a more varied way and always eating some fruit at the end of each meal is a great natural strategy to combat bad breath caused by stomach problems. See more examples in home remedies for stomach.
9. Decompensated diabetes
Uncontrolled, or decompensated, diabetes can also cause bad breath with a smell similar to rotten apples, and this happens due to diabetic ketoacidosis, which is common in these cases and can be accompanied by other symptoms, such as a feeling of intense thirst and dry mouth, intense tiredness and weakness or mental confusion.
Diabetic ketoacidosis occurs because as there is not enough glucose inside the cells, the body starts to produce ketone bodies in order to generate energy, resulting in bad breath and also lowering the pH of the blood, which can be dangerous if you have diabetes. is not properly treated.
What to do: Diabetes should be treated according to the endocrinologist’s instructions, as this will prevent diabetic ketoacidosis. Furthermore, if symptoms of ketoacidosis are detected, it is important that the person goes to the hospital or emergency room immediately to avoid complications. Know how to identify diabetic ketoacidosis.
10. Xerostomia
Xerostomia, popularly known as dry mouth, is characterized by a decrease or interruption in the production of saliva or a change in the composition of saliva, causing the mouth to become very dry, which leads to bad breath.
Generally, bad breath is accompanied by other symptoms, such as thick saliva or difficulty chewing, and is generally caused by smoking, stress, anxiety or even illnesses, such as anemia, lupus or multiple sclerosis, for example.
What to do: It is important to drink plenty of water throughout the day to hydrate the mucous membranes of the mouth and reduce the discomfort of dry mouth, in addition to avoiding smoking. In addition, the doctor may recommend the use of artificial saliva or specific treatment for the disease that is causing the xerostomia. See other causes of dry mouth and what to do.
11. Liver problems
Some liver problems, such as liver failure, can cause bad breath, usually with a sweet smell, due to the liver’s difficulty in carrying out its main functions, such as synthesis of clotting factors, metabolism and elimination of toxins from the body.
Additionally, liver failure can cause belly swelling, yellowing of the skin and eyes, or a general feeling of being unwell. Know how to identify all the symptoms of liver failure.
What to do: When liver failure is suspected, it is important to consult a hepatologist so that the diagnosis can be made, the cause identified and appropriate treatment initiated, which may include the use of medication or even a liver transplant, depending on the stage of the disease.
12. Kidney failure
Renal failure is a disease in which the kidneys lose their ability to filter the blood and eliminate toxins from the body, such as creatinine and urea, through urine, which end up accumulating in the bloodstream and are eliminated by the lungs through the breathing, causing bad breath, with a smell similar to urine.
What to do: The treatment of kidney failure must be guided by a nephrologist, who can recommend antihypertensive and diuretic medications, as this can help eliminate toxic substances that may be accumulated in the body. In more serious cases, the doctor may recommend treatment with hemodialysis or even a kidney transplant. See how kidney failure is treated.
13. Olfactory reference disorder
Olfactory reference disorder is a psychiatric condition in which a person feels like they have bad breath all the time, although it is not noticed by other people.
This condition can generate anxiety, because in addition to feeling like they have bad breath, the person also believes that other parts of the body also have a bad smell, such as armpits or feet, for example.
What to do: You should consult your general practitioner so that tests can be carried out and diseases that can cause bad breath can be ruled out. If olfactory reference disorder is diagnosed, the doctor must refer the person to a psychiatrist, who can indicate the best treatment that can be done with cognitive behavioral therapy or the use of antidepressant medications, for example.