Unfortunately nobody knows what and how any particular med works. There are just too many variables aside from the obvious, male/female, age, weight, sensitivity to chemicals, allergies, developed tolerances, medical fads, stubborn patients, etc. I try to work in partnership with my PDoc when he prescribes meds. There is a lot of back and fort discussion and very careful self observation to decide if something works or not. Unfortunately this happens in a lot of medical cases, in cancer, sometimes chemo works, other times radiation. With a broken bone you might get a permanent cast or a removable one. In my case, if I have a headache I'll take ibuprofen, for skeletal pain from exercise I take Aleve, if I have arthritis pain, or pain in my joints in humid areas I take Tylenol Arthritis. You just have to listen to your body, your gut, and make the most educated decision.