Dr. Alien (1989)

When the mysterious Ms. Xenobia takes over the local college biology class, the dating life of supergeek Wesley Littlejohn takes a serious turn. Littlejohn agrees to be a lab rat for the professor's unusual vitamin research study. Now, thanks to some out-of-this-world supplements, he's been transformed into the campus stud. However, Xenobia has ulterior extraterrestrial motives.