High fever after vaccination

Vaccines train the immune system, and some people feel warm, tired, achy, or unsettled afterwards. A fever that begins soon after vaccination may be related to that response, but a new cough, diarrhoea, painful urination, rash, or exposure to illness may point to another cause. The vaccine type, age, previous reactions, medical history, and timing all matter. A fever does not mean the vaccine caused every symptom that follows it.

Offer fluids, allow rest, and use light clothing in a comfortable room. Measure the temperature with a consistent method and record when the fever started and whether it is improving. Give fever medicine only when appropriate for the person’s age, health, and current medicines, following a clinician’s advice or the label. Do not give aspirin to children or repeat a dose early. Contact the vaccination provider if you are unsure which symptoms need review.

Seek emergency help for trouble breathing, swelling of the face or throat, fainting, widespread hives with weakness, a seizure, severe confusion, or a child who is difficult to wake. Obtain prompt medical advice for a fever that is severe, persistent, or worsening, or for repeated vomiting, poor drinking, markedly reduced urine, or a concerning rash. Do not delay care while trying to decide whether the vaccine or an infection is responsible.

Ask whether the reaction fits the vaccine given, how to monitor it, which fever medicine is suitable, and whether a future dose needs special planning. Tell the clinician the vaccine name, administration time, temperature readings, other medicines, allergies, and any previous vaccine reaction.