Hi my 9 year old daughter has a very bad breath and she's using kids mouthwash but it doesn't help?

Doctor can check: Halitosis (bad breath) reasons: First, her dentist will make sure teeth are polished and there are no cavities, no gum disease. Floss well. Her doctor can check for sinusitis. Chemicals from some foods or drinks diffuse into the flesh in the mouth and throat. These chemical odors keep coming out into the breath for many hours. Some foods cause odors when in the stomach and odors can come back up.

Halitosis: Bad breath can be caused by many different factors, including sinus infections, periodontal problems, smoking, cavities, acid reflux, and your diet. Address all of these possibilities with your dentist and physician, and I'm confident that your problem will at least be minimized, and hopefully eradicated.

Halitosis: Common causes in kids include, but are not limited to, dental decay, infected gums, infected tonsils/adenoids, sinus infection, juvenile diabetes, odor producing foods (onions/garlic/cabbage/etc.), lactose intolerance, food allergies, etc. Please see both her Dentist and her Physician for evaluations.