Is encephalopathy common with sepsis?

Yes: Toxic metabolic encephalopathy can appear in up to 50% of ICU patients (from either drugs or the disease itself), although most studies cite a more reasonable 20-30%. Depends on the infection and how ill/old the patient is.

Very common: Sepsis leads to a generalized inflammatory state throughout the body, called the systemic inflammatory response. This can cause problems in many organs including the brain. Most patients with sepsis have "encephalopathy" which can range from confusion and agitation to coma. Up to 71% of patients with sepsis will be affected. It tends to resolve however as the underlying infection gets better.