Drinking Lactulose light fart without stool may be related to insufficient time or dose of medication, severe constipation, poor gastrointestinal function and other reasons, as follows. Lactulose oral solution has the effect of stimulating intestinal peristalsis, maintaining smooth stool, restoring colon physiological rhythm, etc. It is used in the treatment of chronic or habitual constipation and hepatic encephalopathy. There is farting after drinking lactulose, indicating that the gastrointestinal tract has been peristalsis but not yet stool, related to the following reasons. 1. insufficient medication time or dose: generally take lactulose 1 to 2 days can appear therapeutic effect, but due to the drug onset of time, individual differences, drug dosage and other reasons, there may be no obvious effect after the medication, this time in the guidance of the doctor to increase the amount of time and prolonged use of medication. 2. Severe constipation: For persistent constipation or severe constipation, the effect of single lactulose treatment is not obvious, and lubricating laxative such as liquid paraffin can be added according to the doctor’s instruction, and enema or surgery can be used if necessary. 3. poor gastrointestinal function: for patients with poor gastrointestinal function, due to slow gastrointestinal peristalsis, poor digestive ability, will also appear to drink lactulose light fart not stool situation. There are many other reasons why drinking lactulose farts without stool, it is recommended to consult a doctor under the guidance of medication to avoid adverse effects.