Lactulose | Side Effects, Dosage, Uses & More
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Generic Name:

lactulose, Oral solution

All Brands

  • Cephulac (Discontinued)
  • Chronulac (Discontinued)
A discontinued drug is a drug that has been taken off the market due to safety issues, shortage of raw materials, or low market demand.
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Highlights for lactulose

Oral solution
1

Lactulose is used to treat constipation. It’s also used to treat a brain problem called portal-systemic encephalopathy. This problem is a complication of severe liver disease.

2

This drug comes as a solution you take by mouth. It also comes as a rectal solution. The rectal solution is only given as an enema by a healthcare provider.

3

Lactulose oral solution is available as the brand-name drugs Enulose, Generlac, and Constulose. It’s also available as a generic drug.

IMPORTANT INFORMATION

Diarrhea

This drug may cause diarrhea and lead to severe dehydration. Call your doctor right away if you have severe diarrhea while taking this drug.

Galactose and lactose

This drug contains galactose and lactose (milk sugars). Ask your doctor if this drug is safe for you if you are lactose intolerant or eat a low-galactose diet.

Drug features

Lactulose is a prescription drug. It’s available as an oral solution. It also comes as a rectal solution, which is only given as an enema by a healthcare provider.

Lactulose is available as the brand-name drugs Enulose, Generlac, and Constulose. It’s also available as a generic drug. Generic drugs usually cost less. In some cases, they may not be available in every strength or form as the brand-name versions.

This drug may be used as part of a combination therapy. This means you may need to take it with other medications.

Why it's used

Lactulose is used to treat constipation. It’s also used to treat a brain problem called portal-systemic encephalopathy. This problem is a complication of severe liver disease.

How it works

Lactulose belongs to a class of drugs called laxatives. A class of drugs is a group of medications that work in a similar way. These drugs are often used to treat similar conditions.

See Details

Hot it works

Lactulose belongs to a class of drugs called laxatives. A class of drugs is a group of medications that work in a similar way. These drugs are often used to treat similar conditions.

Lactulose is a synthetic (man-made) sugar. It breaks down in your large intestine and then draws water into the intestine. This softens your stool, which helps ease constipation.

This drug also treats high ammonia levels in the blood due to liver disease. High ammonia levels can lead to portal-systemic encephalopathy. This drug works by drawing ammonia from your blood into your large intestine. Your large intestine then removes the ammonia from your body through your stool.

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lactulose Side Effects

Oral solution

More common side effects

The more common side effects of lactulose can include:

  • burping

  • gas

  • nausea

  • cramps andywhere in the body

If these effects are mild, they may go away within a few days or a couple of weeks. If they’re more severe or don’t go away, talk to your doctor or pharmacist.

Serious side effects

Call your doctor right away if you have serious side effects. Call 9-1-1 if your symptoms feel life-threatening or if you think you’re having a medical emergency. Serious side effects and their symptoms can include the following:

  • Severe diarrhea. This can cause dehydration (very low water levels in your body).

  • Stomach discomfort or pain

  • Vomiting

Pharmacist's Advice
Healthline Pharmacist Editorial Team

Lactulose does not cause drowsiness.

Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs affect each person differently, we cannot guarantee that this information includes all possible side effects. This information is not a substitute for medical advice. Always discuss possible side effects with a healthcare provider who knows your medical history.
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lactulose May Interact with Other Medications

Oral solution

Lactulose can interact with other medications, vitamins, or herbs you may be taking. An interaction is when a substance changes the way a drug works. This can be harmful or prevent the drug from working well.

To help avoid interactions, your doctor should manage all of your medications carefully. Be sure to tell your doctor about all medications, vitamins, or herbs you’re taking. To find out how this drug might interact with something else you’re taking, talk to your doctor or pharmacist.

Medications that might interact with this drug

Drugs you should not use with lactulose

Do not take these drugs with lactulose. Doing so can cause dangerous effects in your body. Examples of these drugs include:

  • Antacids
    • You should not take antacids with lactulose. Antacids may cause lactulose to work less well.

Interactions that can make your drugs less effective

When lactulose is less effective: When used with lactulose, these drugs can make lactulose less effective. This means it won’t work as well to treat your condition. Examples of these drugs include:

  • Antibiotics such as neomycin
    • These drugs may stop the breakdown of lactulose in your large intestine. Your doctor will watch you closely if you’re taking lactulose with an antibiotic.

Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs interact differently in each person, we cannot guarantee that this information includes all possible interactions. This information is not a substitute for medical advice. Always speak with your healthcare provider about possible interactions with all prescription drugs, vitamins, herbs and supplements, and over-the-counter drugs that you are taking.
Drug warnings
galactose digestion warning
People with problems digesting galactose

This drug contains galactose (milk sugar). Ask your doctor if this drug is safe for you.

diabetes warning
People with diabetes

This drug may increase your blood sugar levels. Ask your doctor if this drug is safe for you.

pregnancy warning
Pregnant women

Lactulose is a category B pregnancy drug. That means two things:

  1. Research in animals has not shown a risk to the fetus when the mother takes the drug.
  2. There aren’t enough studies done in humans to show if the drug poses a risk to the fetus.

Talk to your doctor if you’re pregnant or plan to become pregnant. Animal studies do not always predict the way humans would respond. Therefore, this drug should only be used in pregnancy if clearly needed.

breast feeding warning
Women who are breast-feeding

Lactulose may pass into breast milk and cause side effects in a child who is breastfed.

Talk to your doctor about breastfeeding your child. You may need to decide whether to stop breastfeeding or stop taking this medication.

childrens warning
For children

It hasn’t been confirmed that this drug is safe and effective for the treatment of constipation in children younger than 18 years of age.

If your child is taking this drug for complications from liver disease, their doctor will watch them closely during treatment to make sure they have at least two to three soft stools each day. This is because ammonia is removed from your child’s body through their stool. Your child’s doctor will also watch for side effects, such as diarrhea.

call the doctor
When to call the doctor

Call your doctor right away if you become pregnant while taking this drug.

allergy warning
Allergies

Lactulose can cause a severe allergic reaction. Symptoms can include:

  • trouble breathing
  • swelling of your throat or tongue

If you have an allergic reaction, call your doctor or local poison control center right away. If your symptoms are severe, call 9-1-1 or go to the nearest emergency room.

Don’t take this drug again if you’ve ever had an allergic reaction to it. Taking it again could be fatal (cause death).

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How to Take lactulose (Dosage)

Oral solution

All possible dosages and drug forms may not be included here. Your dosage, drug form, and how often you take the drug will depend on:

  • your age
  • the condition being treated
  • how severe your condition is
  • other medical conditions you have
  • how you react to the first dose

What are you taking this medication for?

Constipation

Generic: Lactulose

Form: oral solution
Strengths: 10 g/15 mL

Brand: Enulose

Form: oral solution
Strengths: 10 g/15 mL

Brand: Generlac

Form: oral solution
Strengths: 10 g/15 mL

Brand: Constulose

Form: oral solution
Strengths: 10 g/15 mL
Adult dosage (ages 18 years and older)
  • Typical dosage: 1–2 tablespoons (or 15–30 mL) once per day
  • Maximum dosage: 4 tablespoons (60 mL) per day
Child dosage (ages 0–17 years)

It hasn’t been confirmed that this drug is safe and effective in children younger than 18 years of age for the treatment of constipation.

Portal-systemic encephalopathy (liver disease)

Generic: Lactulose

Form: oral solution
Strengths: 10 g/15 mL

Brand: Enulose

Form: oral solution
Strengths: 10 g/15 mL

Brand: Generlac

Form: oral solution
Strengths: 10 g/15 mL

Brand: Constulose

Form: oral solution
Strengths: 10 g/15 mL
Adult dosage (ages 18 years and older)
  • Typical dosage: 2–3 tablespoons (or 30–45 mL) three or four times per day
  • Dosage adjustments:Your doctor may adjust your dosage every day or every other day until you can produce two or three soft stools per day.
Child dosage (ages 0–17 years)
  • Starting dosage:2.5–10 mL taken by mouth each day in three or four divided doses. Infants will start with the 2.5-mL dose.
  • Dosage increases for older children and adolescents:Your child’s doctor may increase your child’s dosage to 40–90 mL per day taken in three or four divided doses.

Warnings

If your child’s first dose causes diarrhea, their doctor should reduce their dosage right away. If the diarrhea continues, their doctor will likely have them stop taking this medication.

Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs affect each person differently, we cannot guarantee that this list includes all possible dosages. This information is not a substitute for medical advice. Always to speak with your doctor or pharmacist about dosages that are right for you.
Pharmacist's Advice
Healthline Pharmacist Editorial Team

Lactulose comes with serious risks if you don’t take it as prescribed.

If you stop taking the drug suddenly or don’t take it at all

For constipation:

Your constipation may not improve or may get worse.

For portal-systemic encephalopathy:

The ammonia levels in your blood may increase to dangerous levels. This may cause you to go into a coma.

If you miss doses or don’t take the drug on schedule

Your medication may not work as well or may stop working completely. For this drug to work well, a certain amount needs to be in your body at all times.

If you take too much

You could have dangerous levels of the drug in your body. Symptoms of an overdose of this drug can include:

  • severe diarrhea
  • strong stomach cramps

If you think you’ve taken too much of this drug, call your doctor or local poison control center. If your symptoms are severe, call 9-1-1 or go to the nearest emergency room right away.

What to do if you miss a dose

Take your dose as soon as you remember. If you remember just a few hours before your next scheduled dose, take only one dose. Never try to catch up by taking two doses at once. This could result in dangerous side effects.

How to tell if the drug is working

For constipation:

You should start to have normal bowel movements. It may take 24–48 hours for this drug to work./p>

For portal-systemic encephalopathy:

You should have have two or three soft stools per day. High ammonia levels caused by the condition are removed from your body through your stool. This drug may start working within 24 hours, but sometimes it doesn’t begin working for 48 hours or more.

Lactulose is used short-term treatment of constipation.

Lactulose is used for short-term or long-term treatment of portal-systemic encephalopathy.

Important considerations for taking this drug

Store this drug carefully

  • Store lactulose in the refrigerator or at room temperature. Keep it between 36°F and 86°F (2°C and 30°C).
  • Don’t freeze this medication.

A prescription for this medication is refillable

You should not need a new prescription for this medication to be refilled. Your doctor will write the number of refills authorized on your prescription.

Travel

When traveling with your medication:

  • Always carry your medication with you. When flying, never put it into a checked bag. Keep it in your carry-on bag.
  • Don’t worry about airport x-ray machines. They can’t hurt your medication.
  • You may need to show airport staff the pharmacy label for your medication. Always carry the original prescription-labeled box with you.
  • Don’t put this medication in your car’s glove compartment or leave it in the car. Be sure to avoid doing this when the weather is very hot or very cold.

Self-management

If needed, you can mix lactulose with a small amount fruit juice, water, or milk. Drink the mixture right away. Don’t save it for later.

Clinical monitoring

Your doctor will likely monitor certain health issues during your treatment. This can help make sure you stay safe while you take this drug. These issues include:

Electrolyte levels. Your doctor may do blood tests to check your electrolyte levels during your treatment with this drug. Your doctor may do this if you’ve been taking this drug for more than 6 months. This monitoring can help make sure your levels are within the range your doctor thinks is best for you, with the lowest risk of side effects.

Insurance

Many insurance companies require a prior authorization for this drug. This means your doctor may need to get approval from your insurance company before your insurance company will pay for the prescription.

Are there any alternatives?

There are other drugs available to treat your condition. Some may be better suited for you than others. Talk to your doctor about other drug options that may work for you.

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How Much Does lactulose Cost?

Oral solution

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Lowest price for lactulose

Walmart $11.66
Sams Club $11.66
Kroger Pharmacy $13.16
These prices represent the lowest priced national pharmacies for lactulose on GoodRx. They may be lower than your insurance.

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These prices represent the lowest priced national pharmacies for lactulose on GoodRx. They may be lower than your insurance.

Show Sources

Content developed in collaboration with University of Illinois-Chicago, Drug Information Group

Medically reviewed by Creighton University, Center for Drug Information and Evidence-Based Practice on March 25, 2016

Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up-to-date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or other healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.
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