Systemic and systematic are both related to the word system, but they have different meanings.
Steve M. from Springfield, Missouri, wrote, "[What are your] thoughts on the difference between using 'systemic' and 'systematic'?"
Systemic describes something that happens or exists throughout a whole system. It is the newer word; it entered English in the early 1800s.
He has a systemic infection.
The new police chief had to address systemic corruption.
Systematic describes something that was thorough and intentional, methodical, or implemented according to a plan. It is the older word, having entered English around 1670.
Doctors began a systematic treatment plan.
Ending systematic discrimination was his first goal.