Take special care with Optaflu BEFORE receiving the vaccine • you should tell your doctor if your immune system is impaired, or if you are undergoing treatment which affects the immune system, e. g. with medicine against cancer (chemotherapy) or corticosteroid medicines (see Section 2, “ Taking other medicines”). • your doctor or nurse will make sure that appropriate medical treatment and supervision is readily available in case of a rare anaphylactic reaction (a very severe allergic reaction with symptoms such as difficulty in breathing, dizziness, a weak and rapid pulse and skin rash) following the administration.