I also get achey about 2 hours into the infusion for no apparent reason. I bought "hotties" these disposable packs that hunters use to keep their hands warm. I put it over the infusion site and hold it in place with a bandage and it helps very much. When I get home I usually sit and watch TV with a heating pad on low around my arm and that feels really good. We cannot figure out why this happens so we just deal with the symptom. You can get "hotties" at Menards, Farm & Fleet or any home improvement store where outdoor people go.