Bad Breath - Causes & Treatment Bad breath or halitosis could be really nasty at times. It occurs transiently post waking up in the morning due to stagnation of saliva & reduced fluid intake or after consumption of foods like garlic, onions, radish, spices and also tobacco, betel nut and alcohol. The resulting breath takes on a different odour that may last for several hours. Apart from this chronic oral malodour could be a sign of either the dental causes or underlying systemic conditions. Dental causes include poor oral hygiene, dental infections, pyorrhoea, ulcers or oral mucosal lesions. Systemic causes mostly include cases originating from ENT (ear, nose & throat) areas like inflammation in tonsils (tonsillitis), nose (rhinitis), sinus (sinusitis) & pharynx (pharyngitis), upper respiratory tract infections (URTI) & lower respiratory tract infections like chronic bronchitis, lung abscess, asthma, cystic fibrosis, and pneumonia. Gastric & ...