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Children's flu vaccine side effects

Flu vaccines for children are very safe, but like all vaccines, some children may experience side effects. The side effects linked with the flu nasal spray vaccine and flu injections are usually mild and don't last very long.

Common side effects of the flu nasal spray vaccine

The flu nasal spray vaccine has very few side effects, the main one being that children may have a slight runny or stuffy nose for a short time. Other possible side effects include:

  • temperature
  • headache
  • weakness
  • aching muscles
  • loss of appetite

Uncommon side effects can include a rash, swollen face or nose bleed.

If you are concerned about your/ your child’s health at any time please seek advice from your GP or NHS 111 Wales.

Rare side effects of the flu nasal spray vaccine

As with all vaccines, there’s a very small chance of a severe allergic reaction (known medically as anaphylaxis).

Anaphylaxis is very serious, but it can be treated with adrenaline. When it happens, it usually does so within a few minutes of the vaccination. Staff who give vaccinations have all been trained to spot and deal with anaphylactic reactions and children recover completely with treatment.

What to do if your child has a side effect from the flu nasal spray vaccine

If your child has a runny nose after their flu vaccination, simply wipe their nose with a tissue and then discard it (and wash your hands thoroughly).

If your child develops a fever after their flu vaccination, keep them cool by:

  • making sure they don't have too many layers of clothes or blankets on
  • giving them cool drinks

You could also give them infant paracetamol or ibuprofen (in the correct dose and form for their age) to reduce their fever. It’s important to read the dosing instructions on (or in) the packet.

Remember – children and young people under 16 should not take medicines that contain aspirin.

If you're worried about your child, trust your instincts and speak to your doctor or NHS 111 Wales.

If your child has symptoms you think might be COVID-19 follow the current COVID-19 guidelines available at:

Call the doctor immediately if at any time, your child:

  • has a temperature of 39 degrees C or above, or
  • has a fit

How to report a suspected vaccine side effect

The Yellow Card Scheme is a national reporting system, which allows you to report suspected side effects from a vaccine. It's run by the Medicines and Healthcare products Regulatory Agency (MHRA), the regulator of medicines and vaccines in the UK.

If you or your child get any side effects from a vaccine, talk to your doctor, pharmacist or nurse. You can also report side effects directly via the MHRA Yellow Card Scheme or search for MHRA Yellow Card in the Google Play or Apple App Store.

Reporting suspected side effects is important. It allows continued monitoring of a vaccine's safety.

For more information visit



Flu vaccination leaflets and accessible information resources are available at Leaflets and accessible vaccination information.

Last Updated: 03/10/2023 10:45:55
The information on this page has been adapted by NHS Wales from original content supplied by NHS UK NHS website