It’s best to avoid painkillers, unless they are routinely taken for a medical condition. Although the evidence is limited, some painkillers might interfere with the very thing the vaccine is trying to do: generate a strong immune system response.

Vaccines work by tricking the body into thinking it has a virus and mounting a defense against it. That may cause arm soreness, fever, headache, muscle aches or other temporary symptoms of inflammation that can be part of that reaction.

Certain painkillers that target inflammation, including ibuprofen (Advil, Motrin and other brands) might curb the immune response.

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