Why your arm might be sore after getting a vaccine

Pain and rashes are normal responses to foreign substances being injected into our bodies. But how much pain you experience after a shot depends on a lot of factors.

For most COVID-19 vaccine recipients, the poke of the needle is no big deal. In the hours afterwards, however, many go on to develop sore arms, according to anecdotal reports and published data.

That common side effect is not unique to COVID-19 vaccines. But as the United States undergoes its first mass vaccination campaign in recent memory, the widespread prevalence of arm pain is sparking questions about why certain shots hurt so much, why some people feel more pain than others, and why some don’t feel any pain at all.

The good news, experts say, is that arm pain and even rashes are normal responses to the injection of foreign substances into our bodies.

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