Can allergies give you headaches? I have food allergies, and environmental allergies, I take benadryl (diphenhydramine) and claritin and im getting bad headaches a lot.

? Sinus problem. allergies can cause nose and sinus congestion, which in turn can cause headaches, depends also on which part of your head is it in the back or the front, headache can have several causes and you are already on multiple medications, which can be the side effect of any, you take benadryl (diphenhydramine) and claritin, better take only one, but neither will control the congestion, see an allergist for better assessment.