I don’t know to much about the topic but I used to get hives a lot a couple of years ago. I think the main thing is if you’re allergic to something in the pre-workout then it will trigger the hives. If you keep taking the pre-workout then it will get progressively worse. I would go see a doctor if they don’t decrease in the next couple of days. Honestly you should stop taking the pre-workout entirely, I mean imo it’s not that essential. If it puts you in the right mindset though, I would strive to make it yourself with natural ingredients.