Okay, let's cut the bullshit hearsay.
You don't need to go into medicine knowing high school chemistry, definitely not for the undergrad courses. Obviously the graduate degrees will have the baseline prereqs. I did have a chem background but the stuff you need to know is VERY basic and there won't be anything you need to know in the course, especially foundation stuff like this, that won't be at least somewhat covered by the lectures you'll get. It's nothing you can't catch up on and I wouldn't worry about it.