Condition is called Halitosis.....

Indigestion
Constipation
Acid reflux
Dental caries
Gingivitis
Peridontitis
Dental plaques
Cavity....
Sinusitis
Respiratory tract infections....

Homeopathy has best solution for your problem with out any side effects but history of the patient is necessary...
If it is due to Sinusitis or Indigestion or acid reflux or Constipation....