A smell of iron in the breath may be caused by oral diseases, gastrointestinal diseases, respiratory diseases and other reasons. 1. Oral disease: If you suffer from oral disease and inflammation bleeding, such as dental calculus, gingivitis and dental caries, etc., may cause the breath with a ferruginous odor. 2. Gastrointestinal diseases: If you suffer from gastrointestinal diseases, such as gastritis, gastric ulcer. Helicobacter pylori infection, prone to indigestion, resulting in food in the stomach stays too long, and stays too long in the stomach is easy to fermentation, resulting in odor caused by the phenomenon of an iron smell out of breath. 3. Respiratory diseases: iron smell may be the taste of blood, people out of breath with a rusty odor suggests that there may be respiratory bleeding, such as bronchial dilatation and other diseases may lead to bleeding, caused by people out of breath with a rusty odor, need to consult a doctor in a timely manner. A rusty odor of the air out of the patient, should promptly go to the regular hospital to find out the cause of the disease, and under the guidance of a professional doctor to give targeted treatment.