I don't use medications myself (except for aspirine) -- I wouldn't expect other people to use any, either. Unless they're old. Still, if I saw the door hanging open with medicine inside, I wouldn't look. What would be the point? I really don't see how knowing that your friend has funky toes in the winter and he uses cream to get rid of it, in any way satisfies your curiosity? Why would you even want to know?
I mean, you'd be like: "bandaids? check. bandages? check. paracetamol/aspirin? check. biogaze for burn-accidents? check. a non-opened bottle of cough-drink? check." I mean, what interesting could there be in there, unless your friend is a hypochondriac and a medicine-addict? And even then, do you really want to know?
I'm more interested in why people actually place medicine cabinets in their bathrooms; seems like a wastefull place; all you've got in there are your basic aid stuff like bandages and stuff -- won't it be much too humid for that?
I'm also more interested in the sextoy drawer of my female friends... But then when I simply ask them, I get the answers anyway so my curiosity is satisfied.