Hepatic encephalopathy is a frequent and occasionally refractory complication of cirrhosis and is associated with impaired quality of life. Its severity may not correlate with other parameters of liver dysfunction. Although multiple pathogenic mechanisms for the condition have been proposed, most include the participation of bacterial toxins, especially ammonia, produced in the gastrointestinal tract. Treatment options for hepatic encephalopathy at this time are limited to lactulose and neomycin. Lactulose is frequently poorly tolerated, and many patients are non-compliant with its use. In patients with renal insufficiency in whom hepatic encephalopathy is frequently problematic, use of neomycin is contraindicated due to ototoxicity and nephrotoxicity.