To assess the effects of lactulose for the prevention of first episode of altered sensorium (hepatic encephalopathy, primary prophylaxis) in patients with cirrhosis.

Development of hepatic encephalopathy in a patient with cirrhosis is associated with poor survival rate of 10-70% at one year depending upon hepatic and renal functions. Treating patients to prevent development of first episode of hepatic encephalopathy is classified as primary prophylaxis of hepatic encephalopathy and preventing recurrence of hepatic encephalopathy in patients who had previous episode of hepatic encephalopathy is secondary prophylaxis of hepatic encephalopathy

Inclusion Criteria:

• cirrhotic patients(18-70yrs) who never had encephalopathy

Exclusion Criteria:

• history of taking lactulose in the past 6 weeks
• alcohol intake during the past 6 weeks
• hepatocellular carcinoma
• previous TIPS or shunt surgery
• significant co morbid illness such as heart, respiratory, or renal failure
• neurologic diseases such as alzheimer's disease, parkinson's disease and nonhepatic metabolic encephalopathies.
• patients on psychoactive drugs such as antidepressants or sedatives
• who restarted alcohol during follow up