Risks & complications of immunisations

All vaccines are thoroughly tested to ensure they are safe and work before they are licensed and used in the community. After being licensed vaccine safety continues to be monitored to ensure there are no extremely rare reactions that only occur when hundreds of thousands of doses have been given. This article explains common, uncommon and rare reactions to vaccines that have been identified through pre-licensing testing and ongoing safety monitoring.

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Adverse events following immunisation

Managing vaccine reactions

Vaccine reactions and the next immunisation visit

Useful links

Immunisation visits and possible vaccine reactions

Useful Immunisation Websites

Adverse events following immunisation

Anything undesirable occurring after a person receives a vaccine is called an Adverse Event Following Immunisation (AEFI) whether or not it is related to the immunisation. Some events, like getting a runny nose or cough, happen quite often during childhood and it is a coincidence that one starts just after immunisation rather than it being caused by the immunisation. Other events are known to be caused by immunisation.

Vaccine reactions reflect our body’s immune system responding to the immunisation. Not every person receiving a vaccine has a noticeable reaction. Some may have only one noticeable reaction and others may experience two or more.

Common, expected reactions

Common, expected vaccine reactions happen quite frequently. They may involve the whole body such as fever, feeling tired, sleepiness, being irritable, nausea, vomiting, diarrhoea or rash, or they may be where the vaccine was given such as soreness/pain, redness and/or swelling. These vaccine reactions may begin as early as six hours after immunisation. They are temporary, usually mild and go way without any treatment.

Uncommon, expected reactions

Some vaccine reactions are expected and happen somewhere between frequently and rarely. They are uncommon reactions and may include the whole body such as a very high fever (more than 39°C) or they may be where the vaccine was given such as severe pain or extensive swelling that covers the whole upper arm or leg where the vaccine was given. They are temporary and go away without any treatment.

Rare or very rare reactions

The very rare reaction that can occur after receiving any immunisation is a severe allergic response, called anaphylaxis, to an ingredient in the vaccine. The doctors and nurses giving immunisations are trained to manage anaphylaxis and have all the equipment needed. Up to three immunisations out of every one million given can cause anaphylaxis. There is a risk of anaphylaxis every time a person has an immunisation and this is why you and your child are asked to wait at the clinic for 20 minutes are receiving an immunisation.

Other rare or very rare but possible vaccine reactions depend on which immunisation has been given.

The table at the end of this page shows the possible vaccine reactions following each of the immunisation visits on the National Immunisation Schedule. Some common and uncommon vaccine reactions depend on the age of the child receiving the vaccine and how many doses they’ve already had. More detailed information about the individual vaccines is available on the Immunisation Advisory Centre website.

Managing vaccine reactions

Some of the ways to help your baby or child feel more comfortable after immunisation include:

Give them lots of cuddles and fluids. If you are breastfeeding they may want lots of feeds.
Do not rub or massage the injection site.
If the injection site looks sore, red and/or swollen place a cool cloth, or a well wrapped ice pack, over the injection site.
If they feel hot or have a fever undress them until they only have one layer of clothing, such as a singlet and nappy, until they’ve cooled down.
Check that the room isn’t too hot or too cold.
Consider using medication:
- If your baby or child is unsettled or miserable because of pain at the injection site or fever you can give them paracetamol or ibuprofen to help them feel more comfortable. It is very important to follow the dose instructions on the bottle because more than the recommended amount can be dangerous.
- Giving paracetamol or ibuprofen ‘just in case’ they are going to have pain or fever after immunisation is NOT recommended because it is possible that these medicines can affect their immune response to the vaccines.

If you have any concerns about how your baby or child is reacting to immunisation call your doctor or Healthline on their free phone number 0800 611 116 (24 hours a day, every day).

Vaccine reactions and the next immunisation visit

The only vaccine reaction that means a person must never have a particular vaccine again is a severe allergic reaction, called anaphylaxis.

It is safe for people who have had common and uncommon vaccine reactions to have the same vaccine again. It is really important that they have all the vaccine doses needed to protect them from the diseases covered by the vaccine.

If a person has had a rare or very rare vaccine reaction, other than anaphylaxis, it is important that a doctor with specialised medical knowledge about the reaction, and often a doctor with specialised immunisation knowledge, and the person or their parents discuss whether the risks from getting the disease or diseases covered by the vaccine are more serious than the risk of the rare reaction happening again. They can then decide whether to complete the number of vaccine doses needed for protection.

Useful links

The Immunisation Advisory Centre website.

The Ministry of Health immunisation webpage.

The Fight Flu website.

The World Health Organization immunisation webpage.

Immunisation visits and possible vaccine reactions

Immunisation visit6 weeks, 3 months, 5 months	Possible vaccine reactions
Vaccine brand namesInfanrix®-hexa and Synflorix® Diseases these vaccines protect against Diphtheria Tetanus Whooping cough (pertussis) Polio Hepatitis B Haemophilus influenzae type b (Hib) Pneumococcal	Common: Soreness/pain, redness and/or swelling around the injection site. Fever over 38°C. Decreased appetite, vomiting and/or diarrhoea. Irritability, restlessness. Unusual crying. Sleepiness. Uncommon: Fever over 39.5°C. Rare or very rare: Anaphylaxis. Hives. Temporary decrease in platelets (idiopathic thrombocytopenic purpura). Persistent (more than 3 hours) inconsolable screaming. A temporary period of decreased muscle tone and responsiveness, within 48 hours of immunisation (hypotonic, hyporesponsive episode) Fit (convulsion) within 2 days of immunisation. Inflammation of the nerve in the arm causing muscle weakness and pain (brachial neuritis) occurs within four weeks of immunisation, 1- 2 times per 200,000 doses. It may occur in the arm of an infant immunised in the leg or in either the injected or non-injected arm of an older child. Recovery is spontaneous and usually without long term consequences.
Immunisation visit15 months	Possible vaccine reactions
Vaccine brand names Act-HIB™, Synflorix® and M-M-R® II Diseases these vaccines protect against Haemophilus influenzae type b (Hib) Pneumococcal Measles Mumps Rubella	Common: Soreness/pain, redness, swelling and/or induration (area of hard inflammation) around the injection site. Fever less than 39°C. Irritability. Sleepiness. Loss of appetite. Fever over 39.5˚C and/or rash 6–12 days after immunisation. Face/’under jaw’ swelling 10–14 days after immunisation. Mild rash, fever and/or enlarged lymph nodes between two and four weeks after immunisation. Joint symptoms may occur after the vaccine, the incidence of which is age related. More adult women than children get joint symptoms about two to four weeks after immunisation. Uncommon: Fever above 39°C. Diarrhoea and/or vomiting. Rare or very rare: Anaphylaxis. Hives. Itching. Fit (convulsion) with or without fever. Temporary decrease in platelets (idiopathic thrombocytopenic purpura). Brain inflammation (encephalitis) occurs once in one million doses. There may be some long-term effects from this. Inflammation of the layers around the brain and spinal cord (aseptic mumps meningitis).
Immunisation visit4 years	Possible vaccine reactions
Vaccine brandsInfanrix®-IPV and M-M-R® II Diseases these vaccines protect against Diphtheria Tetanus Whooping cough (pertussis) Polio Measles Mumps Rubella	Common: Soreness/pain, redness and/or swelling around the injection site. Fever over 38°C. Decreased appetite, vomiting and/or diarrhoea. Irritability, restlessness. Tiredness. Fever over 39.5˚C and/or rash 6–12 days after immunisation. Face/’under jaw’ swelling 10–14 days after immunisation. Mild rash, fever and/or enlarged lymph nodes between two and four weeks after immunisation. More adult women than children get joint symptoms about two to four weeks after immunisation. Uncommon: Swelling involving the entire thigh or upper arm occurs in 2–3 out of 100 children after administration of the fourth and fifth doses of whooping cough vaccine. It resolves spontaneously without long term consequences. Extensive limb swelling after the fourth dose does not predict an increased risk of a similar reaction following the fifth dose of pertussis vaccine. Rare or very rare: Anaphylaxis. Hives. Fit (convulsion) within 2 days of immunisation. Inflammation of the nerve in the arm causing muscle weakness and pain (brachial neuritis) occurs within four weeks of immunisation, 1- 2 times per 200,000 doses. It may occur in either the injected or non-injected arm. Recovery is spontaneous and usually without long term consequences. Temporary decrease in platelets (idiopathic thrombocytopenic purpura). Brain inflammation (encephalitis) occurs once in one million doses. There may be some long-term effects from this. Inflammation of the layers around the brain and spinal cord (aseptic mumps meningitis).
Immunisation visit11 years	Possible vaccine reactions
Vaccine brandBoostrix® Diseases this vaccine protects against Diphtheria Tetanus Whooping cough (pertussis)	Common: Soreness/pain, redness and/or swelling around the injection site. The pain may be severe enough to prevent normal everyday activities. Fever above 38°C. Headache. Fatigue. Nausea. Uncommon: Fever above 39°C. Muscle or joint stiffness or pain. Rare or very rare: Anaphylaxis. Hives. Itching. Extensive swelling or weakness of the vaccinated limb.
Immunisation visit12 years (girls only)	Possible vaccine reactions
Vaccine brandGardasil® Disease this vaccine protects against Human papillomavirus (HPV)	Common: Fainting. Mild to moderate pain and inflammation at injection site. Uncommon: Severe pain and swelling at injection site. Mild to moderate fever. Rare or very rare: Anaphylaxis.