Bad breath is 1 of the more common symptoms in clinical practice. To measure bad breath, a simpler and better way is to find a few close people and smell specifically whether the patient himself has bad breath. This method is relatively simple and practical, but many patients are reluctant to use this method to measure, mainly due to face problems. Then there are actually some ways for patients to see for themselves if they have bad breath in their mouth. The first can cover the mouth and nose with both hands and then exhale loudly to smell whether the odor is obvious odor. Of course, this situation for rhinitis and cold people may be relatively less sensitive. The second method is that we can use our tongue to lick the inside of our wrist. Wait for a while and smell the area to see if there is bad breath. There is a third way, the patient can look at their tongue in the mirror, usually the normal tongue is pink, but if the tongue is not pink, is a significantly thicker tongue, or yellow and white, it also means that there may be bad breath.