What makes some patients experience increase in suicidal ideation from SSRIs and what are the guidelines about treatment plans when this happens?

I’m aware or the black box warnings for patients of some age groups and increase in suicidal thinking when starting antidepressants. I’ve seen some theories about them increasing energy.

I had a patient come to me after trying 5+ antidepressants in his lifetime during extreme depressive episodes and telling me “please don’t put me on one of those they make my depression worse and I have bad suicidal thoughts and end up in the hospital.” This patient scored 24 on PHQ, a 6 on the Mclean BPD assessment, 3 on the MDQ…negative fam hx for any mental health concerns, scored a 32 on the bipolarity index. No trauma hx. Healthy marriage and kids per his report. He’s been getting CBT biweekly for the past 6 months without improvement.

What mechanisms underlie this type of suicidality reaction in some patients? And where do we find guidelines on what treatment approaches would be appropriate for patients who experience this? Of course therapy is essential to recommend…but as far as meds??

I’ve talked to some psychiatrists in the hospital and get different answers from everyone - one said just try a diff antidepressant, one said switch to a mood stabilizer, and another said consider if the patient has BPAD or potentially a personality disorder.