Allergic Reaction...but much better than previous ones

Have only had a few of these allergic reactions before. This one was much milder. Starts with itching of hands, then redness, followed by rash over much of my body. The other times it progressed to much worse...even something that affected my breathing. This time it just went to the rash over body, then it eased up and rash is fading. So relieved! I think it might have been a weed I pulled out earlier today. The worst part is the fear and not knowing how far it might go...whether to head for the ER right away or wait. I'm on medications for allergies, which I wasn't the other times I had this.