"Caffeine"
"I heard that caffeine, specifically hot coffee or tea, is good for opening the lungs," Alfons said one day, during his and Ed's usual random conversations at the breakfast table.
"Where did you hear that?" Ed asked, the piece of toast falling from his mouth and back onto the plate.
"I overheard some of the medical students talking about it when I went to the University yesterday."
"It's probably just a rumor."
Though that didn't stop the eldest Elric from turning on the kettle the next time Alfons started coughing.