I have a mild concussion, is it ok to masterbate?

Do something else: If trying to stay on the safe side, avoid over-using the brain after a concussion. That means don't study too vigorously, don't take an SAT practice test (nor the real thing), and don't spend time worrying about masturbation. Over-worrying is over-using the brain, so over-worrying is to be avoided. Also, if trying to be safe, just think of masturbation as having the intensity of a sport.