Bad Breath in Children: Causes and Simple Fixes

You lean in for a morning hug and notice it: your child's breath is not as fresh as you expected. You are not alone. A 2025 national poll of parents in the United States, by C.S. Mott Children's Hospital, found that more than a third had noticed bad breath in their child. In most cases the cause is simple and easy to fix at home.

Common causes

• Plaque and a coated tongue. Bacteria build up on the teeth and on the back of the tongue. This is the most common cause, especially when brushing is rushed or the tongue is skipped.
• Morning breath. Saliva slows down during sleep, so bacteria multiply overnight. Some morning breath is normal and usually improves after breakfast and brushing.
• Mouth breathing and dry mouth. Children who breathe through their mouth, snore, or drink little water have less saliva to rinse the mouth naturally.
• Food stuck between teeth. Small pieces of food trapped between back teeth break down and smell.
• Cavities. Decayed teeth can trap food and bacteria, and an infected tooth can give a strong, unpleasant smell.
• Gum inflammation. Red, puffy gums that bleed on brushing are a sign of plaque build-up and can cause bad breath.
• Tonsils, sinuses and a blocked nose. Colds, sinus infections, enlarged tonsils or allergies can all affect breath.
• Something in the nose. In toddlers, a very bad smell together with thick, smelly discharge from one nostril only can mean a small object, such as a bead or a piece of food, is stuck in the nose. This needs to be checked by a doctor. Please don't try to remove it yourself.

Some foods, such as garlic and onions, can also cause short-lived bad breath.

Simple fixes at home

1. Brush twice a day for two minutes with fluoride toothpaste, and help or supervise until around age 7 or 8.
2. Brush the tongue too. Gently brush from the back of the tongue towards the front a few times. A soft toothbrush is enough for most children.
3. Floss once a day where teeth touch, especially between the back teeth.
4. Offer water through the day. Water keeps the mouth moist and rinses away food.
5. Make sure the last brush really is the last. After night-time brushing, offer only water.
6. Choose tooth-friendly snacks such as cheese, vegetables and fruit, and keep sweets to mealtimes.
7. Keep up regular check-ups, usually every six months, so cavities and gum problems are found early.

A note on mouthwash

Mouthwash is generally not recommended for young children, usually under age 6, because they may swallow it. For older children, mouthwash may cover up the smell for a short time but does not fix the cause. If you'd like to use one, ask your dentist which type is suitable, and choose an alcohol-free product.

Dentist or doctor?

See the dentist if:

• Bad breath continues even with good brushing and flossing
• You notice holes, dark spots or broken teeth
• Gums are red, swollen or bleed easily
• There is a bump on the gum, a toothache or a bad taste

See your child's doctor or an ENT specialist if:

• Your child snores loudly, breathes through the mouth most of the time, or has a constantly blocked nose
• There are frequent sore throats or large tonsils
• There is smelly discharge from one nostril
• Bad breath comes with fever, a long-lasting cough or other signs of illness

If the mouth looks healthy at the dental check-up, your dentist can help you decide whether a visit to the doctor is the next step.