The 4-in-1 pre-school booster has been thoroughly tested and has a good safety record.
Although many children will not have any problems after vaccination, some children may have side effects.
These are usually mild and do not last long. They usually happen within 48 hours of the injection.
Very common side effects of the 4-in-1 pre-school booster
More than 1 child in 10 having the 4-in-1 pre-school booster vaccine may have:
- discomfort, redness and swelling at the injection site
- loss of appetite
- irritability or restlessness
- increased crying
- high temperature (fever) of 38C or above
Common side effects of the 4-in-1 pre-school booster
Up to 1 in 10 children having the 4-in-1 pre-school booster may have:
Uncommon side effects of the 4-in-1 pre-school booster
Between 1 child in 100 and 1 child in 1,000 who has the vaccine may have:
- swollen glands
- a rash where the vaccine was injected
Severe allergic reactions
Very rarely, a child has a severe allergic reaction, known as anaphylaxis, soon after the 4-in-1 pre-school booster.
This can happen with any vaccine and is extremely rare. It happens in fewer than 1 in a million vaccinations.
If it happens, it'll be soon after the vaccination and the doctor or nurse giving the vaccine will know how to deal with it.
Children treated promptly make a good recovery.
What to do if your child has a side effect
Some children have some swelling, redness or a small hard lump where the injection was given, and it may be sore to touch.
This usually only lasts 2 to 3 days and does not need any treatment.
If your child gets a temperature over 38C, you can treat them with paracetamol liquid.
Read the instructions on the bottle carefully and give your child the correct dose for their age.
If necessary, give them a second dose 4 to 6 hours later.
If your child's temperature is still high after they have had a second dose of paracetamol liquid, speak to your doctor or call 111.
This NHS leaflet (PDF, 64.4kb) tells you the common vaccination reactions in young children up to 5 years of age and how to treat them.
Monitoring the safety of vaccines
In the UK the safety of vaccines is routinely monitored through the Yellow Card Scheme by the Medicines and Healthcare products Regulatory Agency (MHRA) and the Commission on Human Medicines.
Most reactions reported through the Yellow Card Scheme have been minor reactions, such as rashes, fever, getting sick, and redness and swelling where the injection was given.
Page last reviewed: 27 June 2019
Next review due: 27 June 2022