Start with improving the child's oral hygiene
by ensuring he or she brushes twice a day
and making sure they brush their tongue as
well. Take the child to see a dentist to
exclude oral infections, decay, gum disease
etc. If it's still persistent you may need to
see a paediatrician as well to exclude other
causes.

Bad breath or Halitosis in
children can occur due to several reasons
like poor oral hygiene, mouth breathing,
tooth decay, gum disease, infections in the
mouth, bacteria on the tongue, dry mouth,
tonsil stones, foreign objects in the nose
and some medical conditions.