Some people are med resistant, Dan. It's a struggle for them to find a medication that they can tolerate. I know one person with clinical depression who was finally successful in taking Deplin (a med food, a concentrated form of folate, Vitamin B9).
That works for her; otherwise, she's med free.

The drain on one's nutritional reserves may also be a reason for some of us. The
meds certainly take their share there and leave an acidic residue (or ash) that we
have to manage, as well.

I do so wish that psychiatrists would give people helpful advice about things they can do to improve the side effects of medications, but I've yet to know one who did that. We just have to learn ourselves what to do by experience, in many cases.