Common (affecting up to 1 in 10 people at each dose):
- redness, tenderness and/or swelling at the injection site
- slightly raised temperature
- loss of appetite
- problems with sleeping
Many of these symptoms can be relieved by giving paracetamol (Calpol)if your child is over 2 months, or ibuprofen if your child is over 3 months and weighs more than 5kg (see NHS Choices for more advice on giving painkillers to babies and children).
Rare (affecting up to 1 in 1000 people at each dose):
- high temperatures, sometimes leading to fits (also called convulsions or febrile seizures)
- fainting, numbness and limpness (hypotonia)
You should consult your doctor if these reactions happen after vaccination. This is mainly to check that it is the vaccine causing the symptoms, and not some unrelated disease. Symptoms such as fits can be very worrying for parents, but there is no evidence of long-term effects. Children can normally safely receive vaccines in the future.
As with any vaccine, medicine or food, there is a very small chance of a severe allergic reaction (anaphylaxis). Anaphylaxis is different from less severe allergic reactions because it causes life-threatening breathing and/or circulation problems. It is always serious but can be treated with adrenaline. In the UK between 1997 and 2003 there were a total of 130 reports of anaphylaxis following ALL immunisations, but all of these people survived. Around 117 million doses of vaccines were given in the UK during this period, making the overall rate around 1 in 900,000. Depending on the cause of the reaction, and following expert guidance, the person may be able to have vaccinations in the future.
Reactions listed under ‘possible side effects’ or ‘adverse events’ on vaccine product information sheets may not all be directly linked to the vaccine. See Vaccine side effects and adverse reactions for more information on why this is the case.
See more information on the monitoring of vaccine safety.