- Keep brushing twice a day with fluoride toothpaste while you are ill, and do not share your toothbrush.
- After vomiting, rinse your mouth with water and wait before brushing. Sources suggest waiting between 30 and 60 minutes.
- Cough syrups, cough sweets and many children's liquid medicines can contain sugar. Ask a pharmacist about sugar-free versions.
- Being ill, a blocked nose and some cold and flu medicines can dry your mouth. Sipping fluids helps your mouth and helps prevent dehydration.
- The American Dental Association says you probably do not need a new toothbrush after being sick, unless your immune system is severely weakened.
A cold, flu or stomach bug is not usually a problem for your teeth in itself. But for a few days you may be vomiting, sipping sugary drinks, sucking cough sweets and skipping your usual routine. The American Dental Association's MouthHealthy site says it is important to look after your dental health all year round, but especially when you are sick.
Should you still brush your teeth when you feel unwell?
Yes. MouthHealthy advises keeping up your dental and toothbrush hygiene when you are ill, and the NHS advises brushing at least twice a day with fluoride toothpaste. See how to brush your teeth.
Do not share your toothbrush. The American Dental Association says sharing a toothbrush means sharing germs, which is a particular concern if you have a cold or flu, or a condition that weakens your immune system.
What should you do after vomiting?
MouthHealthy explains that vomiting coats your teeth in stomach acid, and that brushing too soon just rubs the acid over the hard outer layer of the teeth (the enamel). healthdirect Australia says acid softens enamel for about 20 to 30 minutes, until saliva helps wash it away.
Rinse first. The NHS advises rinsing with water or a non-acidic mouthwash after vomiting (in its advice for people who are sick often). healthdirect suggests water or milk, or a fluoride mouthwash while you wait to brush. MouthHealthy suggests water, a diluted mouthwash, or one teaspoon of baking soda in water. The Australian Dental Association suggests a fluoride mouthwash and sugar-free gum.
Then wait before brushing. The sources give different times:
- MouthHealthy (American Dental Association): about 30 minutes.
- healthdirect Australia: at least 30 minutes.
- Australian Dental Association: 60 minutes.
One or two bouts of sickness are not the worry. The Australian Dental Association says that when vomiting happens often, the acid can wear teeth away. If you are sick often, see acid reflux, vomiting and your teeth and tooth wear.
Sugary medicines, cough sweets and lozenges
NSW Health says cough syrups, cough lollies, antacids and some vitamins can contain sugar and, if used regularly, may raise your risk of tooth decay, and that many children's liquid medicines have sugar added for taste. It advises rinsing with water after sugary medicines and asking your GP or pharmacist about sugar-free alternatives. The NHS also advises using sugar-free medicines.
MouthHealthy says many cough drops contain sugar, and the longer a sugary one stays in your mouth, the longer decay-causing bacteria have to feed on it. It suggests checking the label and choosing sugar-free ones. See medicines that affect your mouth.
Some medicines are acidic. The Better Health Channel (Victoria) says that if yours is, rinse with water after taking it and avoid brushing for at least 30 minutes.
What should you drink?
The NHS says the most important thing with diarrhoea and vomiting is to drink lots of fluids, taking small sips if you feel sick. It advises against fruit juice and fizzy drinks, because they can make diarrhoea worse, and says water or diluted sugar-free squash are good choices to help prevent dehydration.
MouthHealthy calls water the safest drink. It says sports drinks may be suggested when you are ill, but unless they are sugar-free they contain a lot of sugar, so do not make them a habit once you have recovered. In tea, it suggests leaving out sugar and lemon if you can, because lemon is acidic. See sugar, acid and your teeth.
Why does your mouth feel dry when you are ill?
The NHS lists dehydration, for example from being ill, as a main cause of a dry mouth, along with breathing through your mouth at night because of a blocked nose. MouthHealthy adds that cold and flu medicines such as antihistamines, decongestants and pain relievers can dry your mouth, which can raise the risk of decay.
To ease it, the NHS suggests regular sips of cold water, sucking ice cubes or ice lollies, chewing sugar-free gum or sucking sugar-free sweets, and lip balm for dry lips. If you have been told to limit how much you drink, for example because of kidney disease, follow your care team's advice; Kidney Care UK suggests sips within your fluid allowance. See dry mouth and kidney disease and your mouth.
Do you need a new toothbrush after being ill?
Probably not. MouthHealthy says that unless your immune system is severely weakened, the chance of reinfecting yourself from your toothbrush is very low. If you are still in doubt, it says, throw it out, especially if the brush is 3 to 4 months old and due for replacing anyway. The American Dental Association says toothbrushes can carry bacteria, but there is no evidence that these bacteria cause health problems.
We did not find UK or Australian health body guidance on replacing a toothbrush after an illness. For routine replacement, see choosing a toothbrush.
If you use a steroid inhaler
Steroid (corticosteroid) inhalers can lead to oral thrush, a fungal infection of the mouth. The NHS says rinsing your mouth with water or brushing your teeth after using the inhaler can help prevent it. NSW Health also advises rinsing with water after an asthma inhaler, particularly a steroid one. The Australian Dental Association suggests rinsing with water or a fluoride mouthwash, using a spacer device, and waiting at least 60 minutes before brushing. Do not stop a prescribed inhaler on your own.
Mouth care in hospital or in bed
A patient leaflet from Calderdale and Huddersfield NHS Foundation Trust lists good mouth care, such as brushing your teeth, among the ways to help prevent pneumonia (a lung infection) in hospital, and says ward nurses can help if you need it. It describes brushing twice a day with fluoride toothpaste, saliva replacement for a dry mouth, mouth care kits if you are not allowed to eat or drink, and keeping your lips moist.
The evidence on pneumonia is less certain. A study summary from the NHS Health Research Authority says research suggests frequent mouth care might prevent pneumonia in hospital, but that the evidence is not yet strong enough to change clinical care. If you are caring for someone who is bed-bound, see caring for someone else's teeth.
- Toothache, or a sharp pain with hot, cold or sweet things, after you have recovered.
- Gums that are painful, swollen or bleed when you brush.
- A dry mouth that does not get better once you are well (a GP can also help).
- White patches, redness or soreness in your mouth, especially if you use a steroid inhaler (a pharmacist can also advise).
- You have been sick often over a long period. Tell your dentist and see a GP about the cause.
- The NHS says to call 111 if you keep being sick and cannot keep fluids down, or have been vomiting for more than 2 days.
- Call 999 or go to A&E (or your local emergency number) if you vomit blood or vomit that looks like ground coffee, have green vomit, a sudden severe headache, a stiff neck and pain when looking at bright lights, or severe difficulty breathing (NHS advice).
- A lot of swelling in your mouth, or finding it hard to breathe, speak, swallow or open your mouth, also needs emergency care (NHS).
Frequently asked questions
Can I brush my teeth straight after being sick?
It is better to wait. Rinse first, then wait at least 30 minutes (healthdirect) or 60 minutes (Australian Dental Association), because acid softens the enamel.
Are cough sweets bad for my teeth?
Sugary ones can be, especially if you suck them often. NSW Health says cough lollies can contain sugar, and MouthHealthy suggests sugar-free cough drops.
Should I throw away my toothbrush after a cold or flu?
Usually there is no need, unless your immune system is severely weakened (American Dental Association). Replace it anyway if it is worn or about 3 months old.
My child's medicine contains sugar. What can I do?
NSW Health suggests rinsing with water afterwards and asking your GP or pharmacist about a sugar-free version. Do not skip a prescribed dose because of the sugar.
Sources
- Cold and flu season, American Dental Association (MouthHealthy), accessed September 2026
- Toothbrushes, American Dental Association (MouthHealthy), accessed September 2026
- Toothbrushes, American Dental Association, accessed September 2026
- Tooth decay, NHS, accessed September 2026
- Bulimia, NHS, accessed September 2026
- Diarrhoea and vomiting, NHS, accessed September 2026
- Dehydration, NHS, accessed September 2026
- Dry mouth, NHS, accessed September 2026
- Side effects of budesonide inhalers, NHS, accessed September 2026
- Dental abscess, NHS, accessed September 2026
- Hospital associated pneumonia (patient leaflet), Calderdale and Huddersfield NHS Foundation Trust, accessed September 2026
- Mouth cAre to Prevent Pneumonia in older people Study (MAPPS), NHS Health Research Authority, accessed September 2026
- Dental erosion, healthdirect Australia, accessed September 2026
- Tooth erosion, Australian Dental Association, accessed September 2026
- Asthma, Australian Dental Association, accessed September 2026
- Medications and your mouth (tip sheet), NSW Health, accessed September 2026
- Teeth and medication, Better Health Channel (Victoria), accessed September 2026
- Loss of taste and kidney disease, Kidney Care UK, accessed September 2026
This article is general information about oral health. It is not a diagnosis or a substitute for advice from a dentist or doctor who knows your situation. If you have pain, swelling, bleeding that does not settle, or a problem that is getting worse, see a dental professional. In an emergency, contact your local emergency service.