Employee with a mental disability

Class–What is the duty of an employer to make accommodations for an employee with a mental disability?  For example, what if an employee was diagnosed with paranoid-schizophrenia, and what if that same employee became delusional without medication.  If the disable employee refused to take his or her medication, and thus became delusion, would the employer be forced to continue to accommodate this employee?  What if the disabled employee’s delusions made him or her potentially dangerous to other employers?  Any difference in your opinion?