One of my closest friends is allergic to Botox, which was exactly as terrible a discovery as you might expect. It started while she was still at the doctor’s office, with a burning sensation at the injection site. (“That’s just your imagination,” the dermatologist said.) That sensation promptly turned into a bizarre, patchy rash. (The dermatologist: “I’ve never seen that before.”) Eventually, it gave way to spasms, which though infrequent were intense enough that her husband and kids could see them as they happened, her facial muscles jumping and writhing under her skin like something out of a horror film.