Why Your Arm Hurts After The Flu Shot

If you’ve ever had a flu shot, you know how it feels. Your arm feels stiff and a little sore. Fortunately, this feeling only lasts a few days and is a sign that the vaccination has worked. But what’s causing the pain in your arm after the flu shot? We’ll explain it to you.


The flu shot works by introducing your body to a foreign substance called ‘antigen’. The antigen, in this case, is a deactivated (dead) virus that resembles the flu virus.

Being exposed to an antigen makes the immune system get to know the virus. It puts your body in the supreme state of preparedness, as it were, for a while. When the body is then attacked by a live flu virus, the immune system immediately recognises it and can fight the virus more quickly.


While fighting the inactive flu virus, all kinds of substances are released into your body, including histamine. Histamine causes a small inflammation in your arm after the vaccination. This inflammation is important because it helps your body combat pathogens and repair damaged tissue. But it also causes the stiffness and pain in your arm that you feel after the flu shot. The flu shot is usually placed in your upper arm, which is why you feel the early immune reaction, the pain, also in this area. 

What to do against the pain

If you suffer a lot from your arm after the flu shot, there are a number of things you can do to reduce the pain. 

For example, you can hold ice against the spot of the injection. This reduces redness and also reduces swelling.

It is also important to keep your arm moving after the flu shot. Because of this, the vaccine will not stay concentrated in one place. 

Finally, you can of course also have the injection placed in your non-dominant arm, so that you can still do anything with your dominant arm. 

Source: Shutterstock
Source: Shutterstock

It is worth it

As annoying as that prick in your arm can be, it’s worth it! Even though you’ve never had the flu, there’s always a chance you’ll get it in the future. In addition, by getting the flu shot, you also contribute to the ‘herd immunity’. This means that you help protect populations for which the flu is more dangerous (children, the elderly and the chronically ill) against the flu. After all, you can no longer infect them. 

Staying up to date with your vaccinations is therefore one of the easiest ways to contribute to common health.  


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