Is Lactulose Good For Liver Disease?

Lactulose is prescribed by doctors to treat severe liver disease symptoms. The way in which lactulose works is by decreasing the absorption of ammonia into the blood via the colon, where it can be removed from the body through a bowel movement. 

A build-up of ammonia can occur in severe liver disease. This is due to a change in blood flow to and from the liver as well as the liver not being as effective in converting the ammonia to urea.  

Lactulose is used frequently to treat constipation, and thus it can result in diarrhea. Treatment with lactulose does not cure liver disease but can help to improve symptoms and increase patients’ intellectual functioning, which can be affected by hepatic encephalopathy. 

The use of lactulose in the treatment of hepatic encephalopathy should always be guided by a doctor. 

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How does lactulose help with cirrhosis and other liver diseases?

Liver diseases and cirrhosis can result in hepatic encephalopathy. This condition can cause a decrease in a person's brain functioning. Symptoms may affect patients in a wide range of severity and can either be short or long-term. Hepatic encephalopathy is generally triggered by the accumulation of toxins in the blood.¹

The liver usually removes these toxins. However, if the liver is unable to do this, toxins such as ammonia accumulate and can lead to cirrhosis, which is advanced liver disease.

Hepatic encephalopathy is the result of blood containing high levels of toxins reaching the brain and other areas of the body. These toxins cause cells within the brain to swell, which can cause a range of symptoms. 

People experiencing hepatic encephalopathy can experience symptoms such as:

  • Forgetfulness

  • Inability to concentrate

  • Difficulty sleeping

  • Confusion

  • Aggression

  • Sluggishness

  • Slurred speech

  • Coma or death

Lactulose is a type of sugar that the gut is unable to absorb. It works to decrease ammonia absorption in a number of ways. One way is by increasing the amount of ammonia taken up by the microbes that colonize the colon, which can be used as their energy source. 

Lactulose also stops the production of chemicals in the gut that are converted into ammonia and prevents ammonia absorption into the gut.

How to take lactulose for liver disease

Lactulose for the treatment of hepatic encephalopathy should always be prescribed by a doctor. Lactulose can be taken either orally as a syrup or rectally as an enema. 


A dose of 15 to 30 mL of lactulose syrup is given two to four times a day to patients with hepatic encephalopathy. The aim is to get two semisoft stools per day. 

For patients with acute (short-term) hepatic encephalopathy, a dose of 45 mL is given hourly until the first bowel movement is made. 


If lactulose is to be taken rectally, it’s usually given as an enema at a dosage of 300 mL in 700 mL of water. After administering the lactulose, the liquid should be retained in the colon for an hour. This treatment can be repeated every two hours. 

Brands of lactulose available on the market

Oral lactulose is sold under several names in the US:

  • Generlac

  • Constulose

  • Kristalose

  • Enulose

  • Constilac

  • Cholac

Side effects of lactulose for liver disease

Using lactulose can cause side effects, which may include:

  • Cramping

  • Increased burping

  • Gas

  • Nausea

  • Bloating

These common side effects should go away within a couple of days. If they don’t go away or if they become severe, talk to your doctor.

More serious side effects of lactulose may include:

  • Discomfort or pain in the stomach

  • Vomiting and/or severe diarrhea, which can cause dehydration. 

If you experience these more severe side effects, call your healthcare provider or emergency services. 

Lactulose can also cause electrolyte imbalances.

Who should avoid taking lactulose?

The use of lactulose for hepatic encephalopathy should always be managed by a doctor. Often patients suffering from liver cirrhosis and hepatic encephalopathy may also be affected by dehydration or a bowel obstruction, in which case lactulose should be avoided. Some individuals should be careful taking lactulose, including:

Patients with galactosemia

Patients who are unable to metabolize galactose should avoid taking lactulose.

People with diabetes

People living with diabetes should avoid taking lactulose as it can impact their blood sugar levels. 

Older adults

The side effects of lactulose can cause more harm to older adults than to younger people. Nausea, vomiting, and diarrhea are side effects of lactulose, which should be avoided in older adults. 

Pregnant women

Pregnant women should avoid taking lactulose. Although some animal research has found that the fetus isn’t negatively affected if the mother has taken lactulose, not enough studies have been done on human participants to know the risks. 

What drugs interact with lactulose?

Lactulose should not be taken with the following drugs: 

  • Antacids: These can change the pH of the colon, which can stop lactulose from working well.

  • Antibiotics: Some antibiotics can affect how lactulose is broken down by your body.

Talk to your doctor about taking lactulose with antacids or antibiotics

The lowdown

Lactulose is a drug that consists of a sugar that’s unable to be absorbed by the body. Lactulose is used to treat hepatic encephalopathy, which is often a result of severe liver disease and can affect a person’s brain function. 

This condition can be caused by a build-up of toxins in the blood when they aren’t effectively cleared by the liver. The toxins then reach the brain, causing confusion and other neurological symptoms.

Lactulose draws the toxins from the blood into the gut, where they can be cleared via a bowel movement. 

Frequently asked questions

How long should you take lactulose for liver disease?

Lactulose is sometimes given rectally and orally for liver disease. Treatment can be repeated every two hours, but the medication may take up to 48 hours to work. Your doctor will determine how long you will need to be on lactulose, as there are many patient and disease factors to consider.

Why is lactulose given to patients with cirrhosis?

Lactulose is prescribed to patients to decrease the amount of toxins such as ammonia in their blood. People with liver disease can have a build-up of toxins in the blood. Lactulose works by drawing these toxins out of the blood and into the colon, where they can be excreted.

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