Using paracetamol to prevent and treat fever after MenB vaccination
Updated 24 November 2022
Applies to England
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The advice in this guide only applies if your baby has had the meningococcal B (MenB) vaccine. If your baby has a fever at any other time you should follow the instructions and dose advice on the product packaging and patient information leaflet (PIL).
What to expect after your baby has the MenB vaccine
Fever can be expected after any vaccination, but is more common when the MenB vaccine (Bexsero) is given with the other routine vaccines at 2 and 4 months. Without paracetamol, more than half of infants will develop a temperature after these vaccines. The fever tends to peak around 6 hours after vaccination and is nearly always gone completely within 2 days. The fever shows the baby’s immune system is responding to the vaccine, although the level of fever will depend on each child and does not show how well the vaccine will protect your baby.
How to reduce the risk of fever
Giving paracetamol soon after vaccination – and not waiting for a fever to develop – will reduce the risk of your child having a fever. With paracetamol, fewer than 1 in 5 children will get a fever and nearly all of these are mild (below 39°C). The paracetamol will also reduce the chance of your baby being irritable or suffering discomfort (such as pain at the site of the injection).
Paracetamol product to use
You should use oral infant paracetamol suspension. This kind of paracetamol comes in liquid form for use in babies and young children. It has a strength of 120mg/5ml.
If you have not already got some paracetamol suspension for infants at home, you should get some from your local pharmacy or supermarket so that you can give the first dose of paracetamol within an hour of the vaccination. There are various products to choose from (including bottles and sachets) but the type needed is infant paracetamol suspension 120mg/5ml.
Junior paracetamol (6 plus) is stronger than infant paracetamol (250mg/5ml) and must not be used in babies.
After which vaccinations you should give your baby paracetamol
Paracetamol is advised for your baby following the MenB vaccinations. The MenB vaccine is usually given at your baby’s first and third immunisation appointments at 2 months and 4 months of age.
Paracetamol is not routinely needed after the Men B booster vaccine given at 12 months of age. By this age the baby’s risk of fever is the same as after other vaccines.
How much paracetamol you should give
A total of 3 doses of 2.5ml (60mg) of paracetamol are recommended following MenB vaccination. You should give the first dose at the time of vaccination or as soon as possible afterwards.
You should then give the second dose of paracetamol around 4 to 6 hours later and a third dose 4 to 6 hours after that (see table below).
The 2.5ml dose should be measured and given either using a syringe or with a 2.5ml spoon (this is usually the small end of the spoon that comes in the pack).
For very premature babies (born before 32 weeks gestation), paracetamol should be prescribed by your doctor according to the infant’s weight at the time of vaccination. You should check with your doctor and follow the instructions on the prescription.
Dosage and timing of infant paracetamol suspension (120mg/5ml) for use after primary MenB vaccinations (usually at 2 and 4 months of age)
| Age of baby | Up to 6 months (usually at 2 and 4 months) |
|---|---|
| Dose 1 | One 2.5ml (60mg) dose as soon as possible after vaccination |
| Dose 2 | One 2.5ml (60mg) dose 4 to 6 hours after first dose |
| Dose 3 | One 2.5ml (60mg) dose 4 to 6 hours after second dose |
The advice to give more than 2 doses of paracetamol to babies aged 2 to 3 months only applies after the baby has had the MenB vaccine. If your baby has a fever at any other time, you should follow the instructions and dose advice on the product packaging and patient information leaflet.
If your baby still has a fever after having had the 3 doses of paracetamol
Some babies may still develop fever after vaccination, even after having 3 doses of paracetamol. In the 48 hours after vaccination, if your baby still has a fever but is otherwise well, you can continue to give your baby the same 2.5 ml dose (60mg) of infant paracetamol (120mg/5ml) suspension.
You should always leave at least 4 hours between doses and never give more than 4 doses in any 24 hour period.
You should also keep your baby cool by making sure they don’t have too many layers of clothes or blankets, and give them lots of fluids. If your baby is breast-fed, the best fluid to give is breast milk.
If you are concerned about your baby’s health at any time, then trust your instincts and speak to your GP or call NHS 111 in England and 0845 46 47 in Wales for advice.
If your baby still has a fever more than 48 hours after vaccination you should speak to your GP or call NHS 111 in England and 0845 46 47 in Wales for advice.
Should you wake your baby to give paracetamol
You should always try and give the first dose of paracetamol as soon as possible after the MenB vaccine. However if your baby is sleeping when the next doses are due, don’t wake them up. You can give it when the baby next wakes as long as there is at least 4 hours between each dose.
Small babies and paracetamol
Paracetamol is approved for managing fever in children from the age of 2 months. The patient information leaflet that comes with the pack may say that children aged 2 to 3 months should only be given 2 doses before talking to a doctor or pharmacist.
Although paracetamol is safe in very young children, the advice on the packaging is there to avoid parents giving paracetamol to a child with an unexplained fever. Such a fever could be a sign of a serious infection and treating this for too long may delay a parent seeking medical help.
As fever after vaccination is common, however, experts have advised that it is OK to give paracetamol for up to 48 hours after the MenB vaccine without seeking medical advice.
Fever in this time period is much more likely to be caused by the vaccine than by an infection. The paracetamol will also make your child feel better, and there is no risk of an over-dose provided you give no more than 4 2.5ml doses in any 24 hour period.
Why the manufacturer’s PIL contains different information
You will find a PIL in the supply of paracetamol you purchase. The PIL with the infant paracetamol suspension 120mg/5ml may provide different dosing instructions from the experts’ recommendations for use following MenB vaccination. In this guidance, we give the details of the specific recommendations for the use of paracetamol following a MenB vaccination. For full information about the paracetamol product, please see the manufacturer’s PIL.
Paracetamol and the booster vaccinations at 12 months
By the age of 12 months your baby’s risk of fever after MenB vaccine is the same as with the other vaccines. So, your baby does not need to take 3 doses of paracetamol with their routine 12 month vaccinations. However, if your baby does get fever at home or appears to be in discomfort, you can give your baby infant paracetamol using the dosing schedule for a child of that age as outlined on the instructions in the packet.