A dentist or physician may notice bad breath during an office visit. Sometimes, the smell of the patient's breath may suggest a likely cause for the problem. For example, "fruity" breath may be a sign of uncontrolled diabetes. A urine-like smell, especially in a person who is at high risk of kidney disease, can sometimes indicate kidney failure.
Your dentist will review your medical history for conditions that can cause bad breath and for medicines that can cause dry mouth. Your dentist also will ask you about your diet, personal habits (smoking, chewing tobacco) and any symptoms. He or she also will ask who noticed the bad breath and when.

Your dentist will examine your teeth, gums, mouth and salivary glands. He or she also will feel your head and neck and will evaluate your breath when you exhale from your nose and from your mouth.