If you have developed a rash you will want to discuss the situation with your surgeon. It may be that you will need to stop wearing the compression garment or put a barrier between your skin and the garment. Your surgeon is the best one to advise you on the next steps to take.
CapeSeasideI appreciate your caution, however you can certainly take Benadryl after mommy makeover surgery to help with the rash. Another option would be topical over-the-counter Cortisone cream. However it is best to check in with your plastic surgeon to confirm my advice. Good luck.