Actually, science-related majors are NOT favored or preferred when it comes to med schools - they actually like diversity in academic backgrounds and the ability to complete the premed core + a non science major is highly valued. Philosophy majors enjoy a higher rate of med school admission than biology majors. So, yes, you can major in IR/PoliSci and take the premed core, AND it not only won’t be detrimental but will be helpful.
Two posts of interest:
http://www.oswego.edu/academics/colleges_and_departments/departments/biology/faculty/mackenzie/homepage/advising/Pre-health_Careers/major_admission_data.html
http://www.gapmedics.com/blog/2014/01/13/non-science-majors-and-medical-school-admissions-standing-out-among-the-applicant-pool
This could be your go-to reference manual/guide:
https://www.amherst.edu/campuslife/careers/act/gradstudy/health/guide