Bad breath, also known as halitosis, can be caused by several factors. Poor oral hygiene is one of the most common causes, as it allows bacteria to build up on the teeth and tongue. This can lead to an unpleasant smell. Another common cause of bad breath is dry mouth, which allows bacteria to thrive. Smoking and certain foods can also contribute to bad breath. However, in some cases, bad breath may signify a more severe condition, such as gum disease or a sinus infection. Talk to your dentist if you are concerned about your breath. They will be able to identify the cause and recommend treatment.