What should you know about flu shot side effects duration?

Arm soreness, mild swelling, tiredness, headache, muscle aches, or a low fever can begin soon after vaccination and usually improve as the immune response settles. The pattern is different for every person. Symptoms that start later, become more severe, or resemble a significant infection may have another cause and should not automatically be attributed to the vaccine.

Keep fluids nearby, rest, and use gentle arm movement for injection-site stiffness. A cool cloth can reduce local discomfort. Check with a clinician or pharmacist before using medicine for pain or fever if you are pregnant, have a long-term condition, or take regular treatment. Note when symptoms began and whether they are improving; this makes a later assessment clearer.

Get emergency help for difficulty breathing, swelling of the mouth or throat, widespread hives, fainting, or sudden severe dizziness. Seek medical advice when symptoms are not easing, are getting worse, or prevent drinking, walking, sleeping, or managing a chronic illness. New chest pain or confusion also needs urgent assessment.

Ask what duration and intensity are expected for your vaccine, how to distinguish a vaccine reaction from an infection, and when a follow-up call or examination is needed.