can anyone take hthsci courses as electives or do you have to be in the health science program?
I'm in life sciences and trying to figure out what to take as my electives next year...
any easier/interesting recommendations --> I don't want to take anything too hard because my required courses will already be challenging

If you satisfy the prerequisites you can take the course. This applies to any course from any department. Though sometimes courses will say seats are reserved when you go to enrol. If that's the case, it can't be helped. If seats are reserved you would need to contact the department for permission and most likely join some waiting list.