When a child has a stomach bug, getting fluids in comes first and the teeth can wait a day or two: give oral rehydration solution as your doctor or pharmacist advises, then go back to normal brushing with fluoride toothpaste as soon as your child is well enough. The Royal Children's Hospital Melbourne describes making sure a child drinks enough as the most important part of caring for gastro. One bout of vomiting is very unlikely to harm children's teeth. What matters more is what happens over the following week: sugary drinks sipped for comfort, brushing that slips, or vomiting that keeps coming back.
Written by Dr James Tran, BDent (University of Sydney), MICOI, GradDip (Oral Implants), general dentist at Lumi Dental in Melrose Park.
The short version
- Fluids first. Small amounts often, using an oral rehydration solution where your doctor or pharmacist suggests it.
- The sugar in a rehydration solution is there for a reason, and a few days of it is a small cost to the teeth.
- Avoid lemonade, ginger ale, sports drinks and undiluted cordial during the illness; hospital advice is that they can make dehydration worse.
- After a vomit, rinse with water and brush once your child is settled. The adult version of this question is covered in our article on vomiting and whether to brush.
- Most toothbrushes do not need replacing after gastro; keep the sick child's brush apart.
- Signs of dehydration need a doctor. A child who is very drowsy or hard to wake needs an ambulance on 000.
The single rule: fluids first, teeth a day or two later
Gastroenteritis is an infection of the stomach and bowel. The RCH notes that the vomiting may settle quickly but the diarrhoea can last up to 10 days, and that babies and young children are more likely to become dehydrated.
The RCH advice is to give small amounts often, even if your child is vomiting, and to offer a drink after every vomit. For older children that means a few mouthfuls every five to 15 minutes. healthdirect says oral rehydration solutions are better than plain water because they contain the right concentration of salts to replace fluids and electrolytes, and that they can be chilled or frozen into ice blocks for a child to suck.
Lemonade, ice blocks and other remedies
Flat lemonade is still a common family remedy, but the RCH lists lemonade, ginger ale, sports drinks and fortified feeds as high in sugar and says they can make dehydration worse. If a child refuses rehydration solution, the RCH suggests half-strength apple juice mixed with water or a regular icy pole, and healthdirect allows very diluted cordial or juice mixed half and half with water, used with caution.
Babies under six months are a different case. Both sources advise taking them to a doctor if they show signs of gastro.
Sugar in rehydration drinks: why the teeth can wait
Some parents hesitate over rehydration solutions because the label lists glucose. That glucose is there on purpose. Research on rehydration solutions describes glucose and sodium working together to help the bowel absorb water, which is why these products work better than plain water.
Decay depends on how often sugar reaches the teeth over weeks and months, so a few days of rehydration solution is a short exposure. In my experience, the dental trouble comes later, when a comforting habit outlasts the bug: a bottle of juice by the bed, or electrolyte drinks kept in the lunchbox for weeks. Our article on electrolyte tablets and hydration powders explains why everyday use is a different matter from short-term use when unwell.
After a vomit: rinse, then brush when your child is settled
Vomit carries stomach acid, which softens the enamel surface for a short time. healthdirect notes that baby tooth enamel is softer than adult enamel and more easily damaged by acid. Its advice is to rinse the mouth with water or milk after vomiting and wait at least 30 minutes before brushing, because enamel stays softer for about 20 to 30 minutes until saliva washes the acid away. The American Dental Association gives similar advice: swish with water, spit, and brush about 30 minutes later.
That advice is evolving, and some newer research suggests brushing with fluoride toothpaste soon after an acid attack may not add measurable wear, as our adult article explains. For a sick child the practical order is the same either way: offer a few sips of water, or a rinse if your child can spit, and brush once they are settled. Never force a toothbrush into the mouth of a child who is still retching.
Brushing a sick child gently
Once the vomiting has eased, brush twice a day as usual with a soft brush and fluoride toothpaste. Use the amount that suits your child's age, which our guide to how much fluoride toothpaste children need sets out. Encourage spitting out the excess rather than rinsing, so some fluoride stays on the teeth.
If the taste of toothpaste sets off nausea, try a smaller amount, a milder flavour within the same fluoride strength, or brushing at the time of day your child feels best. If your child already resists brushing, our tips for when a toddler won't let you brush apply even more when they feel unwell.
Missing a brush on the worst day does far less harm than sugary drinks sipped all week. I usually tell parents to aim for normal brushing once their child is up and playing.
The toothbrush after gastro
The RCH describes gastro as very contagious and advises stopping other members of the household from sharing items with the sick child. The American Dental Association says the number one rule is not to share a toothbrush, especially when sick. It also says you probably do not need to replace a toothbrush after being sick, because the chance of reinfecting yourself is very low unless the immune system is severely compromised, but adds "if in doubt, throw it out", especially if the brush is already three to four months old.
Keep the sick child's brush where it can air dry without touching the others. Many families choose to replace it once the child is well. Our article on sharing toothbrushes in a family covers storage in more detail.
What to do at each stage
| Stage | Drinks | Brushing | Toothbrush |
|---|---|---|---|
| During the illness | Small amounts often; oral rehydration solution as advised; avoid lemonade and sports drinks | Rinse or sip water after vomiting; brush gently once settled, if your child can manage it | Keep it apart from the family's brushes; no sharing |
| First day better | Keep offering fluids; return to normal food as appetite allows | Back to twice a day with fluoride toothpaste | Rinse well and let it air dry |
| Back to normal | Water and milk as usual; stop rehydration products unless advised | Usual routine | Replace if old or if in doubt |
When to get medical help
Dehydration matters far more than teeth. The RCH advises calling an ambulance on 000 if a child is unconscious, very lethargic or hard to wake. It advises going to hospital if a child cannot keep any fluids down and shows several signs of dehydration, such as fewer wet nappies or not going to the toilet often, dark yellow or brown urine, dry lips and mouth, or feeling light-headed or dizzy, or if the vomit is khaki green.
See a doctor if a baby under six months is vomiting or has a fever, if your child is not drinking enough, or if diarrhoea is not improving after 10 days. healthdirect describes severe dehydration as a medical emergency, and a dry mouth is one of its signs.
When vomiting keeps coming back
A single stomach bug is not a dental problem. Vomiting that recurs over weeks, or reflux, is different. healthdirect lists frequent vomiting and reflux among the causes of dental erosion, notes that stomach acid tends to affect the inside surfaces of the teeth, and lists teeth that become sensitive, look shorter, chip more easily or develop sharp edges as signs. If your child has a condition that causes repeated vomiting, mention it to both the GP and the dentist so the teeth can be checked; a general dental check is a good starting point.
How we approach this at Lumi Dental
At Lumi Dental, the dentist examines your child's teeth and gums, and the oral health therapists go through brushing technique, toothpaste amount and drinks with parents and children together. After repeated vomiting or reflux, the team looks for early acid wear. Where a child needs care beyond a general practice, the team refers to a paediatric dentist or hospital service. The whole practice accepts the Child Dental Benefits Schedule for eligible children; read about children's dentistry at Lumi Dental.
Questions patients ask
Should I brush my child's teeth after they vomit?
Rinse first, then brush once your child is settled. healthdirect suggests waiting at least 30 minutes; some newer research suggests the wait matters less than once thought. Either way, use a soft brush and fluoride toothpaste.
Are rehydration ice blocks bad for children's teeth?
Not when used for a few days during illness. healthdirect suggests freezing rehydration solution as one way to get fluids into a reluctant child. Stop them once your child is well.
Do I need to throw out my child's toothbrush after gastro?
Usually not. The American Dental Association says the chance of reinfection is very low, but replacing an old brush is reasonable.
Can I give my child lemonade or sports drinks for gastro?
Hospital advice is to avoid them, because they are high in sugar and can make dehydration worse. Rehydration solution is the first choice; ask your pharmacist if your child will not drink it.
Is the medicine my child takes when sick bad for their teeth?
Some children's liquid medicines contain sugar, so give them at the time your doctor advises and offer water afterwards. Our article on sugar in children's liquid medicines explains how to reduce the risk.
Children's dental care in Melrose Park
If you would like your child's teeth checked after an illness, or help getting brushing back on track, the team at Lumi Dental sees families at Melrose Central, with on-site parking. Read about children's dental care at Lumi Dental or check your child's eligibility under the Child Dental Benefits Schedule. Families visit from Melrose Park, Ryde, Parramatta, Ermington and Rydalmere.
Sources
- The Royal Children's Hospital Melbourne, Kids Health Info: Gastroenteritis (gastro)
- healthdirect: Diarrhoea in children
- healthdirect: Dental erosion
- American Dental Association (MouthHealthy): Cold and flu season, ways to care for your mouth when you're sick
About the author
Dr James Tran is a general dentist at Lumi Dental in Melrose Park. He holds a BDent from the University of Sydney and a Graduate Diploma in Oral Implants, and is a Member of the International Congress of Oral Implantologists (MICOI).
This article is general information only and is not a substitute for an examination and individual advice from a registered dental practitioner. Suitability for any treatment varies from person to person.
