My sis takes her maintenance drugs, lithium and closapine for 4 years already. What are the serious effects that she may get in the future for this?

Long term use. Research shows long term use of lithium is usually well tolerated, but does require monitoring of kidney function. Long term use of clozapine is associated with risk of movement disorder (uncontrolled movement of limbs, face, etc). For info on side effects go to: http://www.ncbi.nlm.nih.gov/pubmedhealth/PMHT0010972/?report=details and http://www.nlm.nih.gov/medlineplus/druginfo/meds/a691001.html.