Switching majors at UCSD

How difficult is it to switch majors from sociology (medicine and science) to Bioengineering? I am a hs senior who got accepted int UCSD under the major of Sociology, but I want to switch to BE. Are there any requirements or precautions I should take in order to switch majors?
I have:
3.96 unweighted GPA
ACT Math: 35
SAT 2 Math: 700
I am taking AP Chem and a duel credit class of Calculus 150 A&B from Cal State Fullerton
Have taken AP Bio

http://be.ucsd.edu/incoming-bioengineering says that “The only way for a student to become a Bioengineering major as a freshman at UCSD is to be directly admitted from high school at the time of entrance into UCSD.”

If you enroll at UCSD as a non-bioengineering major, you must apply into another competitive admission process to enter the bioengineering major. Unfortunately, the UCSD web sites give little information on how difficult it is to get into that major.

It is very difficult. Bioengineering is impacted at UCSD so if you are not a straight admitted, then you will have a difficult time trying to switch majors. I would not enroll at UCSD unless you like the major you were admitted for.