Depending on their age, children can have a habit of putting things up their noses, which may become lodged and lead to bad breath. It's not unusual for children to poke small objects into their mouths and noses. If there is a suspicion of this, it is probably best to allow a doctor to probe and remove the foreign object. There may be an indicator of this activity if there is a discharge from the nose. It's also been reported that small swallowed objects can become lodged in the passages and cause bad breath.

The habit of oral hygiene needs to be instilled in children while they are growing up. It's fairly well established that children are not necessarily fastidious in keeping their teeth and mouths clean, and the presence of old food may provide a good breeding ground for the bacteria that cause decomposition and smelly breath. Children should always be encouraged and taught to maintain the highest standards of oral hygiene, as this is a habit that they will carry with them through their lives.

When considering a case of chronic bad breath in children, the usual factors that create the problem in adults should not be ignored. These would include dry mouth, which creates an environment conducive to the bacteria flourishing. While it should be expected that children would not be so prone to bad breath from chewing tobacco, or from drinking alcohol, they are more prone to diseases that affect the saliva glands, and to getting respiratory or throat and mouth infections. These in themselves may cause direct odor, and they will also aggravate the problem by causing mouth breathing and drying out.

Post nasal drip is a particular problem found in young children which can cause bad breath. The bacteria causing the smelly breath tend to be at home on the back of the tongue, and this is exactly where the nasal drip concentrates. The nasal drip itself is a chemical compound that is reported from research to act as a fuel to the bacteria. It contains protein made up of amino acids that are broken down to hydrogen sulfide and other smells.

If it appears that your child has a persistent bad breath problem, it would be wise to consult your physician for assistance in diagnosing and curing the issue.