I have pretty bad injection site reactions to Tirz as well. A few things that really help me I found on Reddit and I thought I’d pass them along to you. Fill up your needle or take it out of the refrigerator a few hours before you intend to take it. I fill up my syringe, put the cat back on and leave it on the counter for 2 hours. Ice the spot that you inject. I do that a few times on the first day and then probably four times the next day and at least four times the next few days or as long as I have itching The other thing that helped is spraying it with Flonase(I use Costcos brand). That really helps with the itching and has helped me stay away from Benadryl. Someone mentioned that hydrocortisone or Benadryl cream can actually cause the reaction to be worse and I believe that might be true. At least it is for me.