Although I've struggled with hives over the past 25 years, I've had two more bouts recently. In each of these cases, I pulled a muscle and severe hives originated at the site of the pull (in the last case, my hamstring) - between 18-36 hours after working out. So it's quite clear they are related to muscle damage. I read that when a muscle is damaged, an enzyme called CK or Creatine Kinase is released. I'm wondering if I could be allergic to that and I'm having a histamine reaction to the enzyme... or perhaps it's simply a reaction to the muscle damage. These hives are terrible and even with significant dosage every 4 hours, they come and go for a week every time I get them. Any ideas?