What should you know about a flu shot?

The injection presents the immune system with influenza material so it can prepare a response without causing influenza infection. Protection develops after vaccination and can vary as influenza viruses change. The vaccine does not prevent every cough or cold, because those illnesses may have other causes.

An inactivated vaccine cannot reproduce in the body. It may still cause a sore arm, tiredness, headache, or a mild fever for a short time. These reactions generally settle without specific treatment.

Tell the vaccinator about previous vaccine reactions, severe allergies, pregnancy, immune conditions, and current illness. Wear clothing that allows access to the upper arm and remain for the observation period recommended by the clinic. Rest, drink fluids, and use simple comfort measures for local soreness if needed.

Seek urgent help for breathing difficulty, swelling of the face or throat, widespread hives, fainting that does not quickly resolve, or severe weakness after vaccination. Contact a clinician if fever is persistent, symptoms are worsening, or you are unsure whether a reaction is expected. Flu-like illness after a shot should still be assessed on its own features.

Ask which influenza vaccine is suitable for your age and health, when it should be given, and whether any condition or medicine changes the plan. Check what to do if you have a fever on the appointment day and which symptoms after the injection need immediate attention.