Lactulose and Lactose Intolerance

Lactulose is a man-made sugar, commonly used as a stool softener to treat constipation. Lactulose contains lactose and is not recommended for use by people who have been diagnosed with lactose intolerance. Taking this medication to treat constipation if you're lactose intolerant can cause cramping, diarrhea, bloating and stomach pain. Talk with your doctor before you use this stool softer or any other medication to treat a medical condition.

Lactulose is a medication that contains lactose. (Image: milosducati/iStock/Getty Images)


Lactulose is broken down in the large intestines and causes increased water to be added to the stool in the colon, which causes the stool to pass with greater ease. This medication is available in a liquid or pill form and is taken once a day for constipation or up to four times daily for liver disease, according to PubMed Health. If you develop adverse reactions after taking this medication, stop using it and call your doctor immediately for further evaluation.

Lactose Intolerance

Lactose is a sugar that is primarily found in milk. Most sugars that you ingest require an enzyme to break them down into more simple sugars. Lactase is the enzyme required to digest lactose properly. If you don't produce enough lactase in your small intestines, your body will not be able to absorb the sugar and it will pass through your gut undigested. The undigested lactose creates gas, cramping, diarrhea and bloating once it reaches the colon.


If your doctor prescribes lactulose and you develop common lactose intolerant symptoms, you need to inform you doctor. Most lactose intolerant symptoms will develop within 20 minutes or up to two hours after you take the medication. Depending on the severity of your intolerance will determine the degree of your symptoms. You may experience loose stools, stools that float, foul-smell stools, stomach pain, diarrhea, nausea, vomiting, gas and bloating. Call your doctor immediately if you notice blood in your stool.


If your doctor still recommends taking lactulose, she may also prescribe a lactase enzyme supplement. Lactase enzyme supplements provide your digestive system with appropriate amount of lactase to digest the lactose in the medication. When taken as directed, lactase supplements should prevent any lactose intolerance symptoms. If your symptoms persist or become worse, you may have a different medical condition, such as a milk allergy or milk protein intolerance.

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