Mumps Complications Vs Side Effects Of MMR Immunisation

Mumps Complications Vs Side Effects Of MMR Immunisation

The risk of MMR immunisation causing serious harm is extremely rare. MMR is considerably safer than getting mumps. Check out a comparison of the effects of mumps with responses to MMR immunisation.


Complications of mumps

Most children recover from mumps. Unimmunised teenagers and adults who get mumps are more likely to experience severe disease and complications. Complications in people with mumps include:

  • pain and swelling of a testicle (orchitis) in about 1 in 5 teenage or adult males - infertility is rare
  • viral meningitis in up to 15 in 100 people - most make a full recovery
  • pain and swelling of an ovary (oophoritis) in 1 in 20 teenage or adult females - infertility is rare
  • temporary deafness 
  • serious and permanent deafness - this is rare, usually on one side
  • brain inflammation (encephalitis) in about 1 in 6,000 people
  • inflammation of other organs, such as pancreas, nerves, joints, breast, kidney, thyroid and heart
  • death - this is rare

There is an increased risk of miscarriage in pregnant women who get mumps during the first 3 months of pregnancy. There is no evidence that mumps causes damage to unborn babies.

Possible side effects of MMR

After MMR immunisation, a fever of 39.4°C or more happens in 5 to 15 in 100 children. This usually develops 6 to 12 days after immunisation and lasts 1 to 2 days. 5 in 100 children get a rash at the same time.

Side effects of the different components of the MMR vaccine can also include:

  • mild swelling of the glands around the jaw 10 to 14 days after immunisation
  • generalised swollen glands 2 to 4 weeks after immunisation
  • joint pain 2 to 4 weeks after immunisation - this is more common in adult women than children

Rare side effects of MMR

  • inflammation of the brain (encephalitis)
  • idiopathic thrombocytopenia purpura (low platelets)
  • aseptic meningitis 
  • anaphylaxis
  • febrile seizures

Immunisation Handbook 2020 (mumps chapter). Wellington: Ministry of Health. [Accessed 04/07/2022]

This page last reviewed 04 July 2022.

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