Hepatitis B vaccine fever: what to know

Vaccination introduces a harmless form or part of the virus so the immune system can practise recognising it. A raised temperature, tiredness, or soreness where the injection was given may occur while that response develops. Fever does not mean the vaccine caused hepatitis B, and it does not prove that someone has the infection. A vaccine reaction also should not be confused with symptoms such as dark urine or unusual fatigue, which can occur with liver illness and deserve assessment in context.

Offer regular fluids, dress lightly, and allow rest. Check the temperature with a reliable thermometer and note when the fever began and whether it is improving. Use a fever medicine only if a clinician or pharmacist says it is suitable for the person’s age, health conditions, and other medicines; follow the product directions. Do not give aspirin to a child unless specifically prescribed. Keep the vaccination record and arrange any remaining doses through the recommended Hepatitis B Vaccination schedule.

Get urgent help for trouble breathing, swelling of the face or throat, collapse, a seizure, marked drowsiness, or a child who is difficult to wake. Contact a healthcare professional promptly if the fever is high, is worsening, lasts beyond the expected brief reaction, or occurs with repeated vomiting, dehydration, a spreading rash, or severe weakness. A clinician may examine the person and decide whether tests such as a Liver Function Test are appropriate.

Ask which temperature should prompt a call, whether a fever medicine is suitable, and whether another dose should be delayed. Tell the clinician about previous vaccine reactions, allergies, current medicines, and any known Hepatitis B exposure.