A side effect is an undesired effect of a medicinal product or vaccine. Examples of side effects include a mild fever or a sore arm. In addition, the injection site may be a bit red or swollen. Small children can also become listless or tearful. These side effects are generally mild and go away on their own within a few days. Serious side effects are very rare.
Side effects are constantly being studied. That is why we are aware of most of the side effects related to vaccines. Read more on the page about research on side effects, or on the website of the Pharmacovigilance Centre Lareb. Are you unsure about whether you want to have your child vaccinated, because of the possible side effects? Check out the page on doubts about vaccination.
Children sometimes find injections scary and unpleasant. This is completely normal. Occasionally, children may faint from the stress.
Tips
Start talking about the injection appointment at home and tell your child what to expect. More tips about how to explain it are available online.
Try to distract your child calmly, but do not stop the child from watching.
Young children are helped by cuddling and distraction before and after the injection.
Has your child ever fainted from an injection?
Make sure your child eats something before receiving the vaccination.
Let the doctor or nurse at the location know beforehand that your child has fainted from an injection before.
Have your child lie down during the vaccination.
After vaccination, do not let your child get up immediately; have the child rest quietly for a few moments first.
Most children feel unwell for a bit after a vaccination. Most children develop side effects on the day that they get the vaccination. These do not usually last more than 1 to 2 days. The MMR vaccination against measles, mumps and rubella has a delayed reaction, usually after 5 to 12 days. Side effects generally happen because the vaccinations kickstart the body’s immune system. For more information, go to the page on how a vaccine works.
Contact your GP if you are concerned, for example if your child is very ill. Also contact your GP if the fever persists for more than a few days or rises above 39 C.
Tips for side effects after vaccination
If your child is feeling unwell, the following tips may help:
- Moving around after vaccination helps reduce pain, stiffness and swelling at the injection site. For example, you could have your child do cycling movements while sitting or lying down.
- Is your child in obvious pain after the vaccination, or is your baby crying a lot? Consider giving the child a paracetamol later on the day of the injection. Always read the package leaflet for the painkiller first.
- Is the injection site hot or puffy? Cooling can reduce pain and swelling. Soak a flannel or tea towel with cold tap water and place it on the hot, puffy area. Do not use ice cubes, ice packs or cool packs! This can cause frostbite.
- Does your child have a fever? This is a natural reaction, but it may feel scary for a bit. Even so, you do not have to give the child a paracetamol right away. If you choose to do so, always read the package leaflet for the painkiller first.
- If your child has fever, give them enough to drink to prevent dehydration.
The most common side effects after a vaccination are:
Reactions at the injection site
After vaccination, the injection site may be red or puffy. Occasionally, the entire upper arm or thigh becomes red and puffy. It often looks awful and children may be bothered by it for a few days, but it does go away on its own. This reaction is very unlikely to happen again after a next vaccination.
Very occasionally, an abscess with pus may form. It is not known whether this is in response to the vaccine, the injection with a syringe, or a combination of the two. Within the National Immunisation Programme, it only happens 5 to 10 times a year.
Fever and feeling ill
After a vaccination, your body’s immune system goes to work. Read more on the page about how vaccinations work. Because your immune system is activated, you may feel a bit ill and feverish after a vaccination.
Febrile seizure
Febrile seizures are not uncommon in children. It can happen when a fever rapidly rises. The child may twitch or shake their arms and legs, or become unconscious. Occasionally, a child may have this after an injection. It may look like a serious problem and could be very scary for the parents. Fortunately, these febrile seizures are harmless, and are not very likely to happen again after later vaccinations.
| Reported suspected side effects | 2017 | 2018 | 2019 | 2020 |
|---|---|---|---|---|
| Fever | 608 (11.2%) | 699 (13.4%) | 821 (11.1%) | 566 (12.2%) |
| Inflammation at the injection site | 396 (7.3%) | 408 (7.8%) | 489 (6.6%) | 300 (6.5%) |
| Crying | 234 (4.3) | 155 (3.0%) | 295 (4.0%) | 179 (3.9%) |
| Headache | 77 (1.4%) | 121 (2.3%) | 251 (3.4%) | 128 (2.8%) |
| Vomiting | 114 (2.1%) | 131 (2.5%) | 175 (2.4%) | 169 (3.6%) |
An allergic reaction is an excessive immune response of our body to substances that we come into contact with. It does not have to be very serious. Most allergic reactions only cause a minor skin rash and/or itching. Children very rarely have severe allergic reactions from vaccinations. There are no known cases of this in the Netherlands.
Examples of allergic reactions
Allergic reactions can sometimes become more serious if the body is repeatedly exposed to the same substance that triggers the allergic reaction. That may lead to swelling of the mucous membranes, puffy lips, spotty red skin rash and shortness of breath. In very severe cases, blood vessels may dilate and blood pressure could drop. This is called an anaphylactic reaction. In the Netherlands, there is no previous documented case of this severe reaction in children after a vaccination in the National Immunisation Programme.
Antibiotics allergy
Sometimes children are allergic to one of the antibiotics used in the production of vaccines. These antibiotics are neomycin, streptomycin or polymyxin B. Is your child allergic to any of these antibiotics? Then please tell the nurse or doctor before the vaccination is administered, so that you can discuss whether or not vaccination is advisable.
In very rare cases, antibiotics can cause a delayed allergic reaction. These reactions occur at least 4 hours after vaccination. An example of a delayed allergic reaction due to vaccination is itching or skin rash at the injection site. These reactions are harmless and will resolve on their own within a couple of days. If you believe your child has had a delayed allergic reaction after being vaccinated, please tell the nurse or doctor when your child is having their next vaccination.
The page What is in vaccines? provides more information on which antibiotics are used in vaccine production.
No chicken egg protein in vaccines
Vaccines in the National Immunisation Programme are produced without using any chicken eggs. Therefore, none of the vaccines in the National Immunisation Programme contain any residues of chicken egg protein. Children who are allergic to chicken egg protein can be vaccinated with these vaccines without any problems.
All reported side effects are also listed in the package leaflets for medicinal products, including vaccines. These include proven side effects as well as incidents that have not yet been clearly linked to the vaccine. If new (possible) side effects become known, the manufacturer is required to update the package leaflet. For that reason, the list of possible side effects is often very long.
International registration
Side effects are also tracked and reviewed internationally. The Pharmacovigilance Centre Lareb also takes part in these international efforts. If you have a side effect after a vaccination, you can report it to Lareb yourself. Lareb anonymises the reported side effects, and then passes them on to the European Medicines Agency (EMA) and the World Health Organization (WHO).
Compiling international records on side effects makes it easier to detect any rare side effects. As a result and if it is necessary, vaccines are adjusted, the National Immunisation Programme is updated, or additional research is conducted.
Side effects caused by vaccines usually occur because of how the body reacts to the vaccine. Vaccines contain either particles of the virus or bacteria (inactivated vaccines), or weakened viruses or bacteria (live attenuated vaccines). When they enter your body via the vaccine, your body wants to make them go away. Then the immune system responds. That is how the body builds up immunity against the virus or bacteria. But that is also when side effects can occur.
Strict safety requirements for vaccinations
Vaccines are subject to strict safety requirements. Before a vaccine receives marketing authorisation, it is extensively studied and tested. Just like medicines are checked for safety and efficacy, vaccines are investigated to find out how well they work and how safe they are. A vaccine is considered safe if common side effects are mild and severe side effects are rare.
Even if a vaccine is approved and considered safe, research into side effects continues. This is especially important because vaccines are given to healthy children and adults, so the organisations involved are even more critical about side effects.