First, I want to reassure you that you are not the only parent whose child has bad breath (halitosis). In fact, a study published in Pediatric Dentistry in 2003 showed that 23 percent of young children had halitosis. In kids, as in adults, tongue coating, inflammation of the gums (gingivitis), and tooth decay are the most common culprits. Bad breath is thought to be caused mostly by “volatile sulfur compounds” — smelly by-products of the breakdown of proteins and sugars by bacteria in the mouth. Proper dental hygiene can clean the mouth of protein and sugar so that they’re not available to bacteria. You should observe and, if necessary, assist your son as he brushes his teeth. He should load his toothbrush with a pea-sized amount of fluoride-containing toothpaste. He should make sure he brushes all the surfaces of the teeth (think of each tooth as having three exposed sides), and the teeth in back too. It’s particularly important to brush the tongue — especially the back third of the tongue — to help remove any coating that may cause bad breath. Good dental health and regular, yearly visits to the dentist can certainly improve bad breath for most children; however, halitosis can also result from other problems. A bacterial or viral infection in the mouth or throat, such as strep throat, can produce a foul mouth odor. In such a case, a child will usually complain of pain in the throat and will often have a fever. You should definitely take your child to his pediatrician if he has a fever and throat pain. Antibiotics are necessary to prevent complications of strep throat. Other, less common, causes of bad breath are chronic postnasal drip from allergies, sinusitis, or a foreign body stuck in the nose. Children usually have other symptoms with these conditions, like a runny nose. Large adenoids and allergies, which increase the likelihood that a child will breathe through his mouth instead of his nose, can cause the mouth to become dried out, increasing the risk of both tooth decay and bad breath. If you notice that your son usually breathes through his mouth and seems to have chronic nasal congestion, he should be evaluated by his pediatrician. I would start with recommending very good dental hygiene for your son. I do not recommend giving him breath strips or mints, because studies have actually found them to be ineffective in reducing halitosis. Good teeth (and tongue!) brushing should help with both bad breath and cavities. If your son’s halitosis persists despite good tooth/tongue-brushing technique, I recommend that you take him to his pediatrician for further evaluation. Q2. My child has bad breath, especially when she is hungry. She now has dental problems, and her tongue is white. Why is this happening and what can be done? — Anna, New York Bad breath — or halitosis, to use the medical term — is a common problem in adults, but it can also occur in children as young as 2 or 3. The most common cause of halitosis is bacteria in the mouth, which can produce foul-smelling chemicals when they break down proteins. These bacteria are most commonly found on the back of the tongue and in between teeth. Your daughter has both dental problems and halitosis. Some children are at increased risk for these problems because they are “mouth breathers.” When you breathe through your mouth instead of your nose, the amount of saliva in your mouth is reduced. If you have less saliva than you should, you are at increased risk for cavities and associated bacteria, which can cause bad breath. Mouth breathers often have a narrow mouth and may have some whitish discoloration of the tongue. Sometimes halitosis can be a sign of some other problem, such as a sinus or throat infection. Postnasal drip and heartburn (also called reflux) are additional possible causes of bad breath in children and may also be associated with whitish discoloration of the tongue. Your daughter should definitely see a pediatric dentist, who can help with her dental problems and bad breath. In the meantime, she should take good care of her teeth. One of the best ways to improve her bad breath is to decrease the amount of bacteria in her mouth by keeping her teeth clean. Brushing her teeth and tongue, especially the back part of the tongue, can help. Flossing is very important, too, because bacteria that cause bad breath are often found between teeth, where a toothbrush can’t reach. The American Academy of Pediatrics has recommendations for proper dental hygiene for infants, children, and adolescents on its Web site. Good luck! Learn more in the Everyday Health Kids’ Health Center. Questions to cover with your pediatrician.