Trade/other name(s): Acilac, Cholac, Chronulac, Constilac, Constulose, Enulose, Evalose, Generlac, Heptalac, Laxilose
Why would this drug be used?
Lactulose is used to treat constipation. Lactulose is also used to lower blood ammonia levels in patients with liver failure.
How does this drug work?
Lactulose is part of the general class of hyperosmotic laxatives, which pull water into the colon. The extra water in the colon stimulates the normal forward movement of the intestines (peristalsis), resulting in a bowel movement within 24 to 48 hours.
Before taking this medicine
Tell your doctor…
- If you are allergic to anything, including medicines, dyes, additives, or foods.
- If you have nausea, vomiting, rectal bleeding, unexplained abdominal pain, blocked intestine, or any disease of the stomach or intestine. Something other than constipation may be causing your problem, and laxatives may worsen it.
- If you are diabetic or if you are on a low galactose diet. Lactulose contains galactose, and a small amount can be absorbed as sugar.
- If you are planning surgery, colonoscopy, or proctoscopy. Use of cautery during such a procedure might pose an explosion hazard due to hydrogen gas in the intestine.
- If you are pregnant, trying to get pregnant, or if there is any chance of pregnancy. Even though animal studies have shown no birth defects, this drug has not been studied in pregnant women.
- If you are breast-feeding. It is not known if this drug is excreted in human milk. If it is, it may cause unwanted effects in the baby.
- About any other prescription or over-the-counter medicines you are taking, including vitamins and herbs. In fact, keeping a written list of each of these medicines (including the doses of each and when you take them) with you in case of emergency may help prevent complications if you get sick.
Interactions with other drugs
Other medicines may not work as well if taken at the same time as laxatives. Do not take this medicine within 2 hours of your other medicines.
Check with your doctor, nurse, or pharmacist about other medicines, vitamins, herbs, and supplements, and whether alcohol can cause problems with this medicine.
Interactions with foods
No serious interactions with food are known at this time. Check with your doctor, nurse, or pharmacist about whether foods may be a problem.
Tell all the doctors, dentists, nurses, and pharmacists you visit that you are taking this drug.
How is this drug taken or given?
Lactulose is a given as a liquid taken by mouth. When used for constipation, the dose is most often 1 or 2 tablespoons per day. It tastes very sweet. To reduce the sweetness, you can take it with water, milk, or juice.
Take this drug exactly as prescribed by your doctor. If you have questions or do not understand the instructions, talk to your doctor or nurse. Store the medicine in a tightly closed container away from heat and moisture and out of the reach of children and pets.
This medicine may cause diarrhea, which can lead to the loss of vital fluids, nutrients, and electrolytes. To replace the fluid that you lose through diarrhea, try to drink 2 to 3 quarts of fluid a day. Include fluids with electrolytes, such as chicken soup or sports drinks, which are helpful in replacing potassium and salt that are lost in diarrhea. Take the laxative as directed by your doctor. If you have symptoms of electrolyte imbalance, such as dizziness, confusion, lightheadedness, irregular heartbeat, muscle cramps, unusual tiredness or weakness, call your doctor.
If you are taking opioid pain relievers, you should take laxatives regularly to counter their action on the bowel and prevent severe complications such as impaction. Talk with your doctor or nurse about the best laxatives to use and how to take them. Let your doctor or nurse know if you haven't had a bowel movement for 3 days.
To help avoid constipation, try to drink 2 to 3 quarts of fluid a day. Increase the amount of fiber you eat in foods by eating fruits, vegetables, beans, peas, and whole-grain breads and cereal. Talk to your doctor about what kind of exercise may help you.
If you are not taking opioid pain medicine and you use laxatives all the time, your body may forget how to move your bowels normally and you come to depend on laxatives. Talk to your doctor if this is a problem for you.
Possible side effects
You will probably not have most of the following side effects, but if you have any talk to your doctor or nurse. They can help you understand the side effects and cope with them.
- abdominal bloating
- abdominal pain or stomach ache
- loss of normal bowel response when used on a long-term basis*
- dehydration due to fluid loss in diarrhea*
- electrolyte imbalance due to diarrhea*
There are some other side effects not listed above that can also occur in some patients. Tell your doctor or nurse if you develop these or any other problems.
Yes – first approved before 1984 (FDA cannot verify dates of drugs approved before 1984).
Disclaimer: This information does not cover all possible uses, actions, precautions, side effects, or interactions. It is not intended as medical advice, and should not be relied upon as a substitute for talking with your doctor, who is familiar with your medical needs.
Last Revised: 11/17/2009