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Drugs A–Z

Lactulose

Lactulose is a prescription medicine (Osmotic Laxative). The sections below reproduce one FDA label for it, named under "Label". Products in other forms, strengths or from other makers have their own labels, which can differ.

Type
Prescription only (Rx)
Brand names
Enulose, Constulose, Generlac, Kristalose
Drug class
Osmotic Laxative
Taken
Oral
Label
APOZEAL PHARMACEUTICALS INC, revised July 23, 2026 · full label on DailyMed
Generic
FDA-approved (11 companies) · details

What it is used for

For the treatment of constipation. In patients with a history of chronic constipation, lactulose solution therapy increases the number of bowel movements per day and the number of days on which bowel movements occur.

Who should not take it (contraindications)

Since lactulose solution contains galactose (less than 1.6 g/15 mL), it is contraindicated in patients who require a low galactose diet.

Warnings

A theoretical hazard may exist for patients being treated with lactulose solution who may be required to undergo electrocautery procedures during proctoscopy or colonoscopy. Accumulation of H 2 gas in significant concentration in the presence of an electrical spark may result in an explosive reaction. Although this complication has not been reported with lactulose, patients on lactulose therapy undergoing such procedures should have a thorough bowel cleansing with a non-fermentable solution. Insufflation of CO 2 as an additional safeguard may be pursued but is considered to be a redundant measure.

Precautions

General Since lactulose solution contains galactose (less than 1.6 g/15 mL) and lactose (less than 1.2 g/15 mL) it should be used with caution in diabetics. Information for Patients In the event that an unusual diarrheal condition occurs, contact your physician. Laboratory Tests Elderly, debilitated patients who receive lactulose for more than six months should have serum electrolytes (potassium, chloride, carbon dioxide) measured periodically. Drug Interactions Results of preliminary studies in humans and rats suggest that non-absorbable antacids given concurrently with lactulose may inhibit the desired lactulose-induced drop in colonic pH. Therefore, a possible lack of desired effect of treatment should be taken into consideration before such drugs are given concomitantly with lactulose solution. Carcinogenesis, Mutagenesis, Impairment of Fertility There are no known human data on long-term potential for carcinogenicity, mutagenicity, or impairment of fertility. There are no known animal data on long-term potential for mutagenicity. Administration of lactulose solution in the diet of mice for 18 months in concentrations of 3 and 10 percent (v/w) did not produce any evidence of carcinogenicity. In studies of mice, rats, and rabbits, doses of lactulose solution up to 6 or 12 mL/kg/day produced no deleterious effects in breeding, conception, or parturition. Pregnancy Teratogenic Effects Pregnancy category B. Reproduction studies have been performed in mice, rats, and rabbits at doses up to 3 or 6 times the usual human oral dose and have revealed no evidence of impaired fertility or harm to the fetus due to lactulose. There are, however, no adequate and well-controlled studies in pregnant women. Because animal reproduction studies are not always predictive of human response, this drug should be used during pregnancy only if clearly needed. Nursing Mothers It is not known whether this drug is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when lactulose solution is administered to a nursing woman. Pediatric Use Safety and effectiveness in pediatric patients have not been established.

Side effects (adverse reactions)

Precise frequency data are not available. Initial dosing may produce flatulence and intestinal cramps, which are usually transient. Excessive dosage can lead to diarrhea with potential complications such as loss of fluids, hypokalemia, and hypernatremia. Nausea and vomiting have been reported. To report SUSPECTED ADVERSE REACTIONS, contact Apozeal Pharmaceuticals Inc. at tel: 1-833-688-7848 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.

Drug interactions

Results of preliminary studies in humans and rats suggest that non-absorbable antacids given concurrently with lactulose may inhibit the desired lactulose-induced drop in colonic pH. Therefore, a possible lack of desired effect of treatment should be taken into consideration before such drugs are given concomitantly with lactulose solution.

Pregnancy

Teratogenic Effects Pregnancy category B. Reproduction studies have been performed in mice, rats, and rabbits at doses up to 3 or 6 times the usual human oral dose and have revealed no evidence of impaired fertility or harm to the fetus due to lactulose. There are, however, no adequate and well-controlled studies in pregnant women. Because animal reproduction studies are not always predictive of human response, this drug should be used during pregnancy only if clearly needed.

Breastfeeding

It is not known whether this drug is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when lactulose solution is administered to a nursing woman.

Use in children

Safety and effectiveness in pediatric patients have not been established.

Is there a generic Lactulose?

Yes. The FDA has approved generic Lactulose from 11 companies whose approvals are active. The earliest of these was approved in 1996.

An FDA approval does not always mean the generic is already in pharmacies: patent disputes and settlements can delay a launch for years. Your pharmacist can tell you whether a generic is actually available and covered by your plan.

The FDA rates these generics as therapeutically equivalent to the brand ("A" rating): same active ingredient, strength, dosage form and effect. Pharmacists can usually substitute them unless the prescriber says otherwise.

Companies with an approved generic

Apotex, Aurobindo Pharma Ltd, Bajaj, Chartwell Rx, Fresenius Kabi, Lannett Co Inc, Pai Holdings, Pharm Assoc, Pharmazone, Pharmobedient, Taro

Brand-name versions

  • Cephulac Sanofi Aventis Us, approved 1976 Discontinued
  • Chronulac Sanofi Aventis Us, approved 1979 Discontinued

Source: Drugs@FDA (via openFDA), checked October 29, 2026. Marketing status is what companies report to the FDA; whether a pharmacy stocks a product, and what your insurance covers, can differ.

Dosage:
we do not reproduce dosing instructions. The right dose depends on the person and the condition and is set by the prescriber or pharmacist. Dosage section of the full label.

Lactulose in the news

We have not covered this medicine yet. Latest news

Recalls

  • Class II Ongoing

    Lactulose Solution, USP (For oral or rectal administration), 30 mL Unit Dose Cups, Rx Only, Distributed by: Akorn, Inc., Gurnee, IL 60031. ALL NDCs

    Reason: CGMP Deviations: Firm went out of business and could no longer continue stability studies.

    Akorn, Inc.

    Lots, distribution and details
    Product
    Lactulose Solution, USP (For oral or rectal administration), 30 mL Unit Dose Cups, Rx Only, Distributed by: Akorn, Inc., Gurnee, IL 60031. ALL NDCs
    Lots / codes
    All Lots
    Distribution
    Nationwide in the USA and Puerto Rico
    Quantity
    N/A
    Recall started
    April 26, 2023 (Voluntary: Firm initiated)
    Severity
    Could cause temporary or medically reversible health problems; serious harm is unlikely.
    FDA recall number
    D-0815-2023
  • Class II Ongoing

    Lactulose Solution, USP (Oral), 10g/15 mL, packaged in a) 15mL bottles, b) 30 mL bottles, c) 473 mL bottles, and d) 946 mL bottles, Rx Only, Distributed by: Akorn, Inc., Gurnee, IL 60031. ALL NDCs

    Reason: CGMP Deviations: Firm went out of business and could no longer continue stability studies.

    Akorn, Inc.

    Lots, distribution and details
    Product
    Lactulose Solution, USP (Oral), 10g/15 mL, packaged in a) 15mL bottles, b) 30 mL bottles, c) 473 mL bottles, and d) 946 mL bottles, Rx Only, Distributed by: Akorn, Inc., Gurnee, IL 60031. ALL NDCs
    Lots / codes
    All Lots
    Distribution
    Nationwide in the USA and Puerto Rico
    Quantity
    N/A
    Recall started
    April 26, 2023 (Voluntary: Firm initiated)
    Severity
    Could cause temporary or medically reversible health problems; serious harm is unlikely.
    FDA recall number
    D-0814-2023

Have this medicine at home? Compare the lot number and expiry date on your package with the recall. Do not stop taking a prescribed medicine on your own — stopping suddenly can be riskier than the recalled lot. Your pharmacist can check it and usually swap it for an unaffected one.

Get alerts for Lactulose

We will email you if the FDA reports a recall, if its shortage status changes, or when we publish news about it — at most one email a day. No account needed.









Source: FDA structured product labeling, retrieved through openFDA. Label text is shown as published by the FDA, without editing; long sections are shortened, marked […]. openFDA data are not validated for clinical use — always check the current label and ask a doctor or pharmacist about your own treatment. Set ID 72ac130a-de85-464d-9e9b-05cac0c54db1.


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Important: this content is for informational purposes only and is not medical advice, a prescribing instruction, or a recommendation to act. Consult a licensed healthcare professional before taking any medication.

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