Bad breath, medically known as halitosis, is a common problem. Bad breath is usually simple and preventable. Dietary factors as well as tobacco and alcohol use may all be factors in causing bad breath. Poor oral hygiene, gum disease, tooth decay, or mouth infections can also be causes of halitosis. Infections in the lungs, sinuses, or airways can also cause bad breath due to the presence of nasal secretions that may drain into the mouth. Chronic postnasal drip, for example as occurs with sinus infections, can be a cause of bad breath. Coughing up sputum from lung infections can also cause bad breath. Dry mouth (xerostomia) can be a side effect of certain medications, increasing the tendency to develop bad breath. Certain chronic diseases that severely restrict liver or kidney function may also alter the odor of the breath. Other chronic conditions that can be associated with bad breath include diabetes and acid reflux disease.