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Men B vaccine side effects

Common side effects of the Men B vaccine

The most common side effect seen with the Men B vaccine, Bexsero, in babies is a fever, or high temperature. The fever shows that your baby is responding to the vaccine, although not getting a fever doesn’t mean it hasn’t worked.

It's recommended that you give your baby infant strength liquid paracetamol to prevent fever after vaccination. Your nurse will give you more information about paracetamol at your vaccination appointment.

It’s a good idea to have some infant strength liquid paracetamol at home before the two-month vaccination visit. You can buy it from your local pharmacy or supermarket.

Other common side effects of the Men B vaccine include:

  • pain, swelling or redness at the injection site
  • vomiting and/or diarrhoea
  • crying and irritability

Rare side effects of the Men B vaccine

Allergic reaction:

In rare cases, babies can have an allergic reaction to the Men B vaccine soon after the injection. This may take the form of a rash or itching that affects part or all of their body.

In very rare cases, they may have an anaphylactic reaction – a severe allergic reaction – within a few minutes of the vaccination. This can cause breathing difficulties and a person to collapse. It's very alarming at the time, but the doctor or nurse giving the vaccine will have been trained in how to treat these reactions and, providing they receive treatment promptly, babies make a complete recovery.

What to do if your baby is unwell after the Men B vaccine

As with all vaccines, a few babies will have side effects, such as looking red or flushed, crying, feeling a bit irritable and so on, though in general these are mild and short-lived. The vast majority of babies won’t have any problems at all.

Follow the advice of your nurse on how to use infant strength liquid paracetamol to prevent fever after vaccination.

If your baby is unwell at any time after vaccination, or if you're concerned about their health, then trust your instincts and speak to your doctor or call NHS 111 Wales (if available in your area) or 0845 46 47. Never give medicines that contain aspirin to a baby. Never give babies the higher strength paracetamol liquid used for older children.

Monitoring the safety of the Men B vaccine

In the UK, the safety of vaccines is monitored through the Yellow Card Scheme by the Medicines and Healthcare products Regulatory Agency and the Committee on Safety of Medicines. Levels of disease and vaccine uptake are recorded by Public Health Wales, to measure the impact of vaccines on disease.

Most reactions to vaccines reported through the Yellow Card Scheme have been minor, such as rashes, fever, vomiting, and redness and swelling where the injection was given.



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Last Updated: 17/02/2022 16:05:54
The information on this page has been adapted by NHS Wales from original content supplied by NHS UK NHS website