There are many causes of bad breath, the more common can be divided into the following cases: First, there are decayed teeth in the mouth, is the most common cause of bad breath, this situation requires patients to go to the dental clinic to give treatment of decayed teeth, can achieve the purpose of treating bad breath. Second, suffering from inflammation of the nasopharynx, this situation requires a visit to the ENT department, giving the corresponding symptomatic treatment can be relieved after bad breath. Third, patients suffering from gastrointestinal diseases, such as indigestion, chronic inflammation of the gastrointestinal tract can also be accompanied by bad breath. For such cases, in addition to treatment in gastroenterology, maintaining a good lifestyle and a healthy diet is equally important. Of course, maintaining good oral hygiene is also of paramount importance, to do at least every morning and evening brush teeth, brush teeth within three minutes after meals, and do not eat any food after brushing teeth at night, bad breath can be away from us.