Dry Mouth (Xerostomia): Saliva helps cleanse the mouth, removing particles that cause bad odors. Dry mouth can result from salivary gland problems, medications, or continuous breathing through the mouth.
Tobacco Products: Smoking and the use of other tobacco products can cause bad breath and contribute to oral health problems, such as gum disease.
Chronic Diseases: Conditions like diabetes, liver disease, and kidney disease can cause distinctive breath odors. For example, diabetes can produce a fruity smell, while liver or kidney failure can cause a fishy smell.
Gastroesophageal Reflux Disease (GERD): Acid reflux can cause stomach acids to reach the throat and mouth, leading to bad breath.