Bad breath is one of the most common problems which are appearing in every age. One in four people is affected with this condition which is also known as halitosis. There are many varieties of this disorder which are result from the underlying conditions. There are people who are not having breath odor at all or who have just a small breath odor and they are worrying too much about this problem. Also there are many cases when people are having a bad breath and they do not know what the real cause for this problem is. It is very difficult to know how your breath bad is. You should ask your friends, family or relatives to feel how serious is your condition. If you have felt that your breath is bad, then you should review your oral hygiene and habit. You should change something in your oral habit such as drinking plenty of water, brushing your teeth and tongue after eating and using dental floss. After you have made these changes and your breath is still bad, you should visit your doctor. If your condition is serious, then your doctor will refer you to a physician which will tell you what the real cause for your condition is.
Causes of bad breath
When you have bad breath, then the real cause for it is in your mouth. There are many causes for this condition such as
Food: When the food which you eat is breaking down in your mouth as food particles, then they are staying around your teeth which mean they are increasing the bacteria inside of your mouth. This is one of the biggest causes for bad breath. Also there are some foods such as spices, garlic and onions which are reason for this condition. When you have eaten them, then they are entering in your bloodstream. The blood is caring them to your lungs which are a reason for the bad breath. 
Tobacco products: People who are smoking cigarettes are having the biggest chances to get bad breath because this product is making them an unpleasant odor. Tobacco users and smokers are having gum disease in most cases. This disease is also a reason for this condition. [2,3]
bad breath causes
Poor dental hygiene: When people are not washing their teeth every day, then the food stays in their mouths which are a reason for bad breath. Then, on your teeth you can see sticky, colorless or plaque (bacteria) forms. When you are not brushing your teeth daily, then the plaque is irritating your gums. In this case they can form plaque – filled pockets which are located between your gums and teeth. Also when you are not washing your tongue, then your tongue is collecting the bacteria which are a reason for this. [2,3]
Dry mouth: The saliva which is in your mouth is very helpful for removing the particles which are a reason for the bad breath. A xerostomia or also known as dry mouth is a condition when your saliva is decreased and this is a reason for the bad breath. This is a condition which is naturally occurring during the night which is leading to condition known as morning breath. This condition is getting worse when you are sleeping with open mouth. But if you have chronic dry mouth, then this is caused by some diseases or some problems with the salivary glands. [3,4]
Medications: There are some medications which when are consumed are a reason for bad breath. These medications are also leading to the previous mentioned condition known as dry mouth. Also there are medications which are causing a bad breath because when they are breaking in your body, then they are causing you a bad breath. 
Infections in your mouth: After you have made some oral surgery such as tooth removal or if you have mouth sores, tooth decay or gum disease, then your chances to get bad breath are increased. 
Other mouth, nose and throat condition: This condition in some cases can occur as a result from the small stones which are forming in the tonsils. They are covered with bacteria which are leading to this condition. Also if you have chronic inflammations or infections in your throat, nose or sinuses, then these cases are a reason for bad breath.
Other causes: Also there are other causes for the bad breath such as metabolic disorders and cancers. They are making a bad breath because they are producing some chemicals in the body which are resulting in mouth odor. [5,6]
 Aylikci BU, Colak H. Halitosis: From diagnosis to management. Journal of Natural Science, Biology and Medicine. 2013;4(1):14–23.
 Setia S, Pannu P, Gambhir RS, et al. Correlation of oral hygiene practices, smoking and oral health conditions with self perceived halitosis amongst undergraduate dental students. Journal of Natural Science, Biology and Medicine. 2014;5(1):67–72. doi:10.4103/0976-9668.127291
 Cortelli JR, Silva Barbosa MD, Westphal MA. Halitosis: a review of associated factors and therapeutic approach. Brazilian Oral Research. 2008;22(1).
 Du M, Li L, Jiang H, et al. Prevalence and relevant factors of halitosis in Chinese subjects: a clinical research. BMC Oral Health. 2019;19.
 Bollen CML, Beikler T. Halitosis: the multidisciplinary approach. International Journal of Oral Science. 2012;4(2):55–63. doi:10.1038/ijos.2012.39
 American Chemical Society. ‘Sniff-cam’ to detect disease by analyzing bad breath. Science Daily. 2019. Retrieved from www.sciencedaily.com/releases/2019/07/190731125426.htm