I keep getting hives! Is it okay to take Benadryl (diphenhydramine) every day?

Preferable to find c. It is preferable to find cause or trigger for hives. Whether drug induced, infection, or food allergy. In many case there is no direct cause and antihistamines may be necessary .There are non sedating antihistamines which work as well or better than benadryl (diphenhydramine).
No. Benadryl (diphenhydramine) has many unintended side effects. You should not take it every day. If you are getting hives frequently, you are allergic to something - perhaps a soap or detergent, for example. You should see your doctor for a thorough history, blood work, and possible allergy testing.