Yes, you can get the flu jab whilst on your period. There are no known problems associated with receiving a flu vaccine during menstruation.
Some studies do suggest your menstrual hormones will increase your pain sensitivity. In other words, you might perceive the pain and soreness from the flu jab differently if you’re on your period. If you’re someone who’s already sensitive to vaccinations, you might feel the effects of the flu vaccine needle more intensely during your period so you might want to consider planning your flu jab around your cycle. However, the flu jab does not affect your hormones and cannot make you unwell so there is no medical reason to delay.
In conclusion, you can safely and effectively have the flu jab when you are on your period.