A woman, aged 23, has developed a skin rash as well as nausea and vomiting, after taking an antimicrobial drug for a short time. The skin rash is red and quite itchy and is spreading over her entire body. The physician stops the medication because of this allergic reaction. The patient has also had hay fever during the summer and fall for the past few years and recently has demonstrated a severe reaction on several occasions to insect bites. What kind of hypersensitivity are these allergic reactions?