Smelly breath from the nose may be caused by nasal foreign bodies, chronic sinusitis, atrophic rhinitis and other factors. 1. Nasal foreign body: If the foreign body exists in the nasal cavity for a long time, it is easy to cause secondary infection, which may produce purulent and foul-smelling secretion, so the breath out of the nose is very smelly. 2. Chronic sinusitis: the stimulation of long-term chronic inflammation may lead to excessive secretion of purulent mucus, accumulating in the nasal cavity, if it can not be discharged in a timely manner, after an abnormal fermentation, may produce their own can smell the odor. 3. Atrophic rhinitis: atrophy of the nasal mucosa, may produce a large number of pus crusts, after protein decomposition, usually the smell of rotten eggs, which leads to the nose out of the gas is very stinky, just can not smell. Nose exhaled breath stinks is an abnormal phenomenon, you should consult a doctor in time, clarify the cause of the disease, and actively treat it, so as not to delay the condition.