How to reduce mouth odour. i brush twice a day but feels i have a bad breath. is there any way to reduce that.?

Sinus infection?: Sinus infection can cause bad breath. Also, one's tongue can harbor bad breath-causing germs so make sure that you brush your tongue after you brush your teeth. See your dentist regularly to keep teeth/gums in good condition. Acid reflux, gastritis, lung disease (ex: abscess), and certain foods can also cause bad breath. Definitely worth seeing your doc if it doesn't get better.