I think the main meds given for BPD are to help keep a person calm. I used to take anti-depressants. And I have had anti-anxiety meds. They have some bad effects, but nothing extreme. However, I did have to go through a bunch before I found some that worked best. None actually "cure."

Has your therapist mentioned DBT (Dialectical Behavioral Therapy)? It is considered a great approach for helping with this problem--but the patient has to be motivated and follow through on the homework assignments.