One of the requirements for maintaining your F-1 status is that you enroll in a full course load every semester. If you have a medical or valid academic reason for needing to carry less than a full course load, you may obtain permission, prior to dropping below full time, from ISS. You will need to submit a request for Reduced Course Load authorization.
A full course load for all undergraduate students is 12 hours each fall and spring semester.
A full course load for all graduate students is 9 hours each fall and spring semester.
Enrollment in the summer is optional unless it is your first or last term. If you begin your studies during the summer or complete your program at the end of the summer, then you must also carry a full course load during that term.