Please tell the doctor or nurse administering your vaccine about any important aspects of your medical history, and about any medication you are currently taking. Flu vaccines do not interact with any other vaccine or medication. However, any treatment that might reduce your immunity can reduce the effectiveness of the immune response caused by the vaccine.
One thing to note is vaccinations can briefly affect the results of certain types of blood tests (serology tests), so if you have a blood test within a few days of being vaccinated, please ask the person taking the blood sample to mention your flu jab on the laboratory form.
If you do have any concerns, you can speak with your doctor or nurse at the time of your vaccination or in advance and discuss your concerns. They will be able to put your mind at ease with further information.