Side-effects of immunisation

Will my baby have side-effects after her immunisations?

Your baby may experience mild side-effects after her immunisations. All medicines, including immunisations, can occasionally cause some side-effects (PHE 2013).

Try not to worry if your baby does have side-effects such as a mild fever or lump at the injection site. They shouldn't last for long (ATAGI 2013, PHE 2013).

If your baby has an unexpected, long-lasting or severe reaction to a vaccine, see your doctor or immunisation nurse (ATAGI 2013).

What side-effects might my baby have after her immunisation?

Your child may be upset for a little while after her immunisation. She may be irritable and off-colour that evening.

Most babies don’t have any other reaction (NHS 2015). But some babies have other side-effects, such as:

• a mild fever
• pain, swelling or redness at the site of the injection
• nausea or vomiting
• diarrhoea
• drowsiness or tiredness
  (ATAGI 2013, PHE 2013)

These side-effects usually appear within the first few days of your baby having the vaccine and don’t last long (ATAGI 2013). She may also develop a small, hard lump (nodule) at the injection site that lasts for weeks or months, but this shouldn’t need treatment (ATAGI 2013).

There’s a chance that all immunisations may cause a fever. If this happens, treat it straight away, but not before the symptoms appear (ATAGI 2013).

Keep a close eye on your child if she develops a high temperature. Occasionally, young children with a high temperature develop convulsions (seizures or fits). These are rare. Your child may be more at risk of having a convulsion if she's had one before, or if there's a family history of seizures.

See your doctor straight away if your baby:

• is younger than three months old and has a temperature of 38 degrees C or more
• is younger than six months old and has a temperature of 39 degrees C or more
• has a seizure
  (NCCWCH 2013, NHS 2014, RCHM 2008)

Some vaccines may cause other side-effects, as described below.

What side-effects might the MMR and MMRV vaccines cause?

The MMR and MMRV vaccines can occasionally cause mild, temporary side-effects one to three weeks after your baby is immunised. Symptoms can include rashes, a low fever and feeling out of sorts for a short while (ATAGI 2013, NHS 2015). These symptoms go away quickly and don’t have any long-term effects.

Don't worry if your child develops a rash. She’s not contagious and it doesn't mean she has measles, rubella or chickenpox (ATAGI 2013). She's just having a reaction to the live but weakened viruses in the MMR or MMRV vaccine as her body builds immunity against the diseases.

What side-effects might the rotavirus vaccine cause?

Some babies develop diarrhoea or vomiting after receiving the rotavirus vaccine (ATAGI 2013).

The rotavirus vaccine has also been shown to slightly increase the risk of intussusception in the week after your baby has the vaccine, especially if it’s her first dose (ATAGI 2013). Intussusception is a rare bowel condition when one section of the bowel slides into the next, like a telescope (Tidy 2013).

If your baby has intussusception, she will cry and may draw her legs up to her stomach (Tidy 2013). She may vomit, look pale, have blood in her poo. Most babies recover completely, especially if they get quick treatment. You should contact your doctor immediately if your baby has these symptoms and she’s recently had the rotavirus vaccine.

For a week or so after your baby’s rotavirus immunisation, be extra careful to wash your hands well after changing her nappy. This will help avoid the small risk of you catching the weakened version of the rotavirus used in the vaccine (ATAGI 2013).

Could my baby have a severe allergic reaction to a vaccine?

With all immunisations, there’s an extremely rare possibility that your child may have a severe allergic reaction, called anaphylaxis (ATAGI 2013, PHE 2013). Anaphylaxis usually occurs within five minutes of receiving a vaccine, but can occur within hours.

Symptoms include a hives-like rash, swelling of the skin, lips or face, vomiting or breathing problems (ATAGI 2013, PHE 2013). The chances of this happening really are tiny, only about one in a million.

You'll be asked to stay at the health clinic or your doctor's office for about 15 minutes after your child has had his injections, just to make he's fine (ATAGI 2013). But if you're worried at all about any side-effects, mild or otherwise, you could always ask to stay on a little longer.

Find out more about what to expect on the day of your baby’s immunisations.