Hi, I have used Botox, Xeomin or Dysport for over 30 years. The swelling associated with a Xeomin treatment typically is quite minimal. You may want to call and speak with the expert Xeomin injector that performed your treatment. Like all "needle based" therapies, Xeomin injections can cause slight swelling. Ice therapy would be more effective than Benadryl in those situations. Benadryl is for the treatment of allergic reactions. If any of these neurotoxins (neuromodulators) are injected in too high of a dose or too close to the eyebrows...this can result in the "joker" look or eyebrows that appear droopy. While these treatments are readily available, it always best to be certain that you are being treated by an experienced injector. Hope this helps.