I take 40 mg of Vyvanse for ADHD and 20mg of prozac for anxiety and I think 20 mg of olmeprazole for reflux. Is it safe to take Advil and Benadryl (diphenhydramine)?

Advil (ibuprofen) a good choice. On your current medications you should have no problem taking Advil (ibuprofen) at usual and recommended dose. At higher doses of any of these medications, one could get the serotonin syndrome (which has been written about in this column.