Bad breath and egg odor may be caused by oral calculus, periodontitis, chronic gastritis, etc. You can treat bad breath by paying attention to oral hygiene, taking medication and other methods. 1. Oral calculus: daily not pay attention to oral hygiene, such as brushing teeth is not thorough, do not brush teeth before going to bed, etc., will lead to excessive accumulation of plaque, the formation of dental calculus, stimulate the gums, bad breath will occur into the egg flavor. 2. periodontitis: oral cleaning is not thorough, food debris exists in the mouth to stimulate the periodontium caused by gingivitis, the mouth is more prone to breeding bacteria, bad breath can occur in the egg flavor. 3. Chronic gastritis: when chronic gastritis combined with Helicobacter pylori infection, dyspepsia, bad breath can also occur in the egg flavor. When bad breath occurs, you should pay attention to oral hygiene and hygiene, and timely to the hospital for further treatment to clarify the cause.