When a child's breath smells, the timing usually points to the cause. Breath that is stale on waking but fine after breakfast is normal overnight dryness. Breath that stays unpleasant all day tends to come from plaque on the teeth and coating on the tongue, and a sudden foul smell with a runny nostril on one side needs a doctor rather than a toothbrush.
Serious illness is an uncommon cause. Most of the time the source sits in the mouth, nose or throat and can be found with a careful look.
Morning breath on its own is normal
Saliva flow drops during sleep, and the bacteria that live on the teeth and tongue release sulphur gases while the mouth is quiet. Nearly every child, and adult, wakes with some odour. If it fades once your child has eaten, had a drink and brushed, there is usually nothing to chase.
It becomes more noticeable in children who sleep with their mouth open. A blocked nose from a cold, hay fever or large adenoids pushes them to breathe through the mouth all night, and a dry mouth smells stronger. We cover the wider effects on teeth and jaw growth in our article on mouth breathing in children.
All-day odour usually starts with missed plaque and the tongue
Children brush the front teeth well and skip the same places every night: the gumline, the inside surfaces and the back molars. Plaque left there feeds odour-producing bacteria. The top of the tongue, especially towards the back, carries a coating of bacteria and food debris that many children never brush at all.
A few changes often help:
- An adult checks or finishes brushing, morning and night, until the child can reliably reach every surface (usually about eight years of age, and sometimes later).
- A soft brush is swept gently over the tongue at the end of each clean.
- Floss goes between any teeth that touch, where food packs in.
- Water, rather than juice or cordial, is the drink between meals.
Our guides to cleaning baby and toddler teeth and cleaning the tongue show the technique in more detail.
Decay and sore gums can hold on to the smell
A cavity is a sheltered pocket where food sits and breaks down, and it cannot be cleaned out with a brush. Inflamed gums around erupting teeth or partly exposed molars can trap debris in the same way. An infected baby tooth may produce a bad taste as well as a smell, sometimes with a small pimple on the gum. If you see brown or black spots, a broken tooth, or a swelling, book a dental visit. Our article on dental infection in children explains the warning signs.
Tonsils, sinuses and the back of the throat
Some children have tonsils with deep pits (crypts) that collect debris and bacteria. Small, pale, foul-smelling lumps called tonsil stones can form there and cause odour even when the teeth are spotless. Postnasal drip from a cold, allergies or sinusitis coats the back of the tongue with mucus that smells in a similar way. These are questions for your GP, particularly when tonsils are large, often infected or linked with snoring.
One nostril, a bad smell and a toddler: think of a foreign object
Small children push beads, food, foam and toy parts into their noses and do not always tell anyone. Days later the object can cause a thick, often smelly discharge from one nostril and very unpleasant breath. If your child has one-sided nasal discharge with a strong odour, see a doctor promptly rather than waiting for it to settle.
Rarer medical causes
A few general health problems change breath odour, including some stomach, metabolic and kidney conditions. These are uncommon in otherwise well children and usually come with other symptoms, such as tiredness, unusual thirst, vomiting or weight change. If the breath smell is unusual (fruity or ammonia-like, for example) or your child seems unwell, a GP is the right first stop.
Questions parents ask
My child brushes twice a day. Why is the smell still there?
Brushing often misses the tongue, the gumline and the back teeth. If those are well cleaned and the smell persists, look at mouth breathing, the tonsils and the nose next.
Will mouthwash fix it?
Mouthwash masks odour for a short time and is not a substitute for cleaning. Many products are not designed for young children, who may swallow them. Ask your dentist or OHT before using one.
Who should I see first, a dentist or a GP?
If you notice spots on the teeth, gum swelling or toothache, start with a dentist or OHT. If the problem seems to be the nose, tonsils or general health, start with your GP. Either can refer on if needed, and a routine check is a good time to raise it, as our guide to a child's first dental visit describes. Adult breath problems are covered separately in our bad breath guide.
Having it checked
At Lumi Dental our dentists and oral health therapists see children for check-ups, cleans and prevention, and eligible children can be bulk billed under the Child Dental Benefits Schedule. If your child's breath has not improved after a couple of weeks of careful brushing, a check can rule out decay and gum problems. Family offers are listed on our offers page.
This article is general information and not a substitute for advice from your dentist or doctor.
