Dear practo user Bad breath can have multiple reasons. First is intraoral causes like lodged food particles, cavities, swollen spongy gums , calculus etc. Teeth and gums need to be cleaned and medication used for oral related bad breath. Sometimes it's related to spicy food, cool drinks, masalas intake etc. Restrictions on diet will help. It can be caused due to gastrointestinal disorders like ulcers, acidity etc. Etiology needs clinical evaluation. Sometimes respiratory problems,  diabetes, and hormonal problems also can cause bad breath. If there are no oral causes found, then there is a chance of systemic involvement. Cause has to be ascertained clinically.

Normal cause is Ulcers in stomach mucosa. A dentist will suggest oral hygiene  measures and anti ulcer treatment course.

Most common intraoral cause is dirty teeth/ cavitation. You need get the scaling/ filling done which will be confirmed only after checking the teeth