What should you know about hepatitis B vaccine injection?

A hepatitis B vaccine injection trains your immune system to recognise hepatitis B without causing the infection. It is given into a muscle by a trained healthcare professional, and protection is built through the vaccination schedule recommended for your age and circumstances.

The vaccine presents the immune system with a harmless hepatitis B surface protein rather than the whole virus. Your body can then make an immune response and remember it. The injection cannot give you hepatitis B. It also does not treat an existing infection, so a clinician may discuss testing if there has been a possible exposure or if symptoms such as fatigue or dark urine are present.

Mild soreness, redness, or swelling near the injection site can occur. Feeling tired or having a low fever for a short time may also happen as the immune response develops.

Tell the vaccinator about previous vaccine reactions, a serious allergy to a vaccine ingredient, pregnancy, immune conditions, and medicines that affect immunity. Keep any record of the dose and ask when the next dose is due; completing the recommended schedule matters because the timing supports a lasting immune response.

After the injection, remain in the clinic for the observation period they advise. Gentle movement of the arm is reasonable, while a cool compress can ease local discomfort. For personalised guidance, read about [Hepatitis B Vaccination](/treatments/preventive-care-and-vaccination/hepatitis-b-vaccination/).

Seek urgent medical help for trouble breathing, swelling of the face or throat, widespread hives, fainting, or marked weakness after vaccination. Contact a clinician if the injection-area reaction is worsening, you develop persistent fever, or you feel significantly unwell. A vaccine reaction is different from hepatitis B symptoms; ongoing dark urine, yellowing of the eyes, or unusual fatigue deserves medical assessment.

Ask which schedule applies to you, whether testing is needed before or after vaccination, and how a missed dose should be handled. You can also ask whether a liver function test is appropriate after a suspected infection or exposure.