Nothing, absolutely nothing.
There is no requirement for you to be a biology or chemistry major to get into medical school. You have your standard biology, chemistry, organic chemistry, physic, etc. requirement, but nowhere does it say that you are required to be in a science major. One of my biggest pet peeves is people saying that you can’t get into medical school unless you’re in a hard science major, I like many other premeds am a hard science major (biochemistry and molecular biology, yes one major), but I unlike some of my colleagues do not believe that you have to be a science major to get into medical school.