Identifying whether you have bad breath can be done through your own breath test, saliva test, flossing verification, and feedback from people close to you. 1. Breath test: Use your own hands to bend your palms and place them 2 to 3 cm in front of your mouth, and breathe out towards your palms. Afterwards, smell the odor in the palm of the hand, if there is a foul smell, it means that there is bad breath. 2. Saliva test: the patient can use the tongue to lick the back of the hand, so that the saliva on the back of the hand residue, if there is a foul odor after drying may have bad breath. 3. Flossing verification: You can use dental floss to clean the crevices of the teeth, with tartar remaining on the floss, and try to smell the floss. If there is an odor from the floss, it means there is bad breath. 4. Feedback from people close to you: you can let people close to you smell their own mouths, if there is a bad taste in the mouth, it means that there is bad breath. 5. Observe the tongue: If there is bad breath, there may be white or yellow secretions on the surface of the tongue. The main reasons for bad breath are like to eat heavy food, gastrointestinal diseases, oral problems and so on. If the bad breath is caused by dietary problems, it can be improved by changing dietary habits and paying attention to the oral environment. If the bad breath is caused by other diseases, you need to go to the hospital to get a clear picture of the cause of the bad breath and get treatment under the doctor’s guidance.