What should you know about an accidental double dose of hepatitis B vaccine?

Hepatitis B vaccination uses an inactivated vaccine to train the immune system; it cannot cause hepatitis B infection. An extra dose may cause the usual local or general vaccine reactions, such as soreness, redness, tiredness or a mild fever. The significance depends on the person's age, health, vaccine product and the dates of earlier doses.

The extra injection does not automatically mean the entire vaccination plan has failed. A clinician or vaccination service can check the record and decide whether later doses should follow the original schedule.

Write down the date, product name, dose, injection site and clinic, and keep any vaccination record. Contact the vaccinating clinic or a healthcare professional for confirmation and documentation. For comfort, rest, drink fluids and use a suitable pain or fever medicine only if you normally can take it and the label or clinician supports its use.

Do not arrange further doses until the record has been checked. Tell the clinician about pregnancy, immune problems, allergies and any previous reaction.

Seek urgent help for trouble breathing, swelling of the face or throat, widespread hives, fainting or severe weakness after vaccination. Contact a clinician promptly for a high or persistent fever, worsening injection-site swelling, severe pain or any reaction that concerns you.

Which product and dose were given, and how should it be recorded? Does the extra dose change my next appointment? What symptoms should prompt urgent help, and do my health conditions or medicines affect the plan?