The pre-reqs you would take for med school and pharm school are pretty much the same. The exact ones depend on the school.
Here's a list of some classes you pretty much will have to take for either:
General Chemistry + Lab (2 semesters)
Organic Chemistry + Lab (2 semesters)
General Biology + Lab (2 semesters)
Physics + Lab (1-2 semesters)
Calculus
English
These ones kinda vary more:
Economics
Speech
Psychology
Sociology
Microbiology
Anatomy and Physiology (2 semesters)
Biochemistry
Molecular or Cell Biology
Other General Education Classes or Upper Division Science Classes
My impressions about pharm school and med school courses is that you sort of split your time between more core science and applying that knowledge, so actual patient counseling and diagnosis type classes.
Look at the FAQS
here. Get some experience in both. Think about other factors that are important to you, like required training time, salaries, free time, etc.