Maybe. There are two types of Ibuprofen allergy: a. Allergy specific to Ibuprofen alone vs. B. Allergy to all of the NSAID containing drugs (naproxen, ibuprofen, aspirin). It is possible to ascertain through interview and allergy testing whether or not you can tolerate other nsaids. I would recommend you see a board certified allergist.
You can't. If you're allergic to one NSAID (non-steroidal anti-inflammatory drug), it's safest to avoid all of them. Each reaction can be worse than the one before, and you could have a life-threatening reaction.
Ibuprefen Allergy. You need to see an allergist. First off, you need to see if you are truly allergic to ibuprofen. Have you ever taken aspirin, naproxen, motrin, etc. If you have and have been safe, then you really need to be evaluated. Additionally, there is much debate if NSAID allergy exists, so you need to find out and discuss the reactions you have when you take ibuprofen. See an allergist.