When you are epileptic Piercings are often discouraged, all of them. If you have epilepsy you probably know more about the symptoms of the disorder. Discuss this with your piercer.
An honest, good, professional piercer will consult with you and ask the opinion of your doctor when in doubt.
If you still want to get a piercing you should ask your doctor whether it is wise and what you or your piercer could expect.
In any case, you should always inform your piercer about such matters so that he or she knows what to do when things go wrong.