I've read that a person who has asthma sym's can be desensitized to aspirin but someone who gets only mild hives from aspirin cannot be. true?

Not true: Most people who are sensitive to Aspirin (also to nsaids such as Ibuprofen ) react to the way these medications block inflammatory pathways. Desensitization can be performed with increasing doses of Aspirin very slowly. There is a risk of reactions. The desensitization effect will continue only as long as one continues to take aspirin. Stop aspirin, and you are back to being sensitive.

Maybe aspirin ok: It is true that studies of hive reactions have failed to show benefit of desensitization. However it is also true that many of these people can tolerate Aspirin if it is needed for other conditions such cerebrovascular or heart disease. Consider seeing a board certified allergist about this. You can find one at aaaai.Org.