Prescription medication · Osmotic Laxative
lactulose
Also sold as Enulose, Kristalose. This medicine treats and prevents portal-systemic encephalopathy.
Data updated 2026-05-15
- 37,033
- FDA reportsModerately reported
- $0.01
- Generic price (NADAC)
lactulose (Enulose) is a prescription Osmotic Laxative. This medicine treats and prevents portal-systemic encephalopathy.
Lactulose is a medicine that helps treat and prevent problems with your brain caused by liver disease. It works by reducing the amount of ammonia in your blood.
Verify with FDA → · CMS NADAC pricing →
Drug Pricing (NADAC)
Generic Price
$0.01/unit
Generic Available
Yes (13 manufacturers)
Pricing data from NADAC (CMS), effective December 18, 2024. Compare all drug costs →
What it does
This medicine treats and prevents portal-systemic encephalopathy.
Common side effects
Gas, Bloating, Belching
Key warnings
If you need a low-galactose diet, you should not take this medicine.
The sections below are summarized in plain English from lactulose's FDA-approved prescribing information. They describe what the official label says, and are not personal medical advice.
How It Works
Lactulose is a sugar that is not digested in your body. It travels to your colon where it is broken down by bacteria. This process makes the colon more acidic, which helps to draw ammonia from the blood into the colon, where it is then removed from the body through bowel movements.
How to Take It
Take lactulose by mouth as directed by your doctor. The usual adult dose is 2 to 3 tablespoonfuls (30 to 45 ml) three or four times a day. You can adjust the dose every day or two to have 2 or 3 soft bowel movements daily. For a quick effect, you may take 30 to 45 ml every hour.
This is a plain-language summary of lactulose's FDA labeling, not individualized dosing advice. Ask a pharmacist or prescriber before changing how you take this medication.
Pregnancy & Breastfeeding
Tell your doctor if you are pregnant or breastfeeding before taking this medicine. It is not known if lactulose can harm your unborn baby. It is also not known if lactulose passes into breast milk.
This is a plain-language summary of lactulose's FDA labeling, not individualized advice. Ask a pharmacist or prescriber about pregnancy or breastfeeding on this medication.
Missed Dose
If you miss a dose, take it as soon as you remember. If it is close to your next dose, skip the missed dose and continue with your regular schedule.
This is a plain-language summary of lactulose's FDA labeling, not individualized advice. Ask a pharmacist or prescriber what to do about your specific missed dose.
Storage
Store lactulose solution between 36° to 86°F (2° to 30°C), and do not freeze it.
Side Effects (from patient reports)
Based on 37,033 FDA adverse event reports.
Most-reported reactions
Adverse reactions in FAERS for lactulose, by number of reports
- Feeling sick to your stomach
Feeling sick to your stomach
2,523 reports
- Having trouble passing stool
Having trouble passing stool
2,497 reports
- Accidentally losing your balance and hitting the ground
Accidentally losing your balance and hitting the ground
2,240 reports
- Throwing up
Throwing up
2,047 reports
- Feeling very tired
Feeling very tired
2,028 reports
- The end of life
The end of life
1,939 reports
- Difficulty breathing
Difficulty breathing
1,910 reports
- Loose, watery stools
Loose, watery stools
1,892 reports
- An unpleasant physical sensation
An unpleasant physical sensation
1,711 reports
- Lung infection
Lung infection
1,687 reports
What this shows Bars show how often each reaction was reported, not how likely it is to happen, a report records a temporal association, never proof that the drug caused it.
Reports over time
Adverse-event reports filed for lactulose each year to the FDA Adverse Event Reporting System (FAERS).
Year-to-year volume tracks usage, prescribing, and scrutiny, not a change in per-patient risk. Source: FDA FAERS.
Where lactulose sits
lactulose has more FDA adverse-event reports than 68% of the drugs FAERS tracks. A high position reflects how widely a drug is used and watched, not how dangerous it is.
Percentile across all drugs PlainMeds tracks by FAERS report volume. The dot is lactulose; the line is the median (50th percentile).
FDA Adverse Event Report Analysis
Detailed analysis of 37,033 reports from the FDA Adverse Event Reporting System (FAERS). Reports span 1997–2025.
Total Reports
37,033
Reports Mentioning Death
6,511
17.6% of reports — not proof of cause
Hospitalization Reports
20,384
Top Indication
Product Used For Unknown Indication
Gender Distribution
Age Distribution
Most Reported Adverse Reactions (FAERS)
| # | Reaction | Reports |
|---|---|---|
| 1 | NAUSEA | 2,524 |
| 2 | CONSTIPATION | 2,497 |
| 3 | FALL | 2,241 |
| 4 | VOMITING | 2,047 |
| 5 | FATIGUE | 2,027 |
| 6 | DEATH | 1,939 |
| 7 | DYSPNOEA | 1,910 |
| 8 | DIARRHOEA | 1,892 |
| 9 | PAIN | 1,711 |
| 10 | PNEUMONIA | 1,687 |
| 11 | HYPOTENSION | 1,536 |
| 13 | CONFUSIONAL STATE | 1,482 |
| 14 | PYREXIA | 1,394 |
| 15 | ASTHENIA | 1,326 |
| 16 | ABDOMINAL PAIN | 1,266 |
Reactions in Death Reports
Reactions in Hospitalization Reports
Source: FDA FAERS (Adverse Event Reporting System) FDA FAERS (Adverse Event Reporting System) Reports are voluntary and do not establish causation
Serious Warnings
If you need a low-galactose diet, you should not take this medicine. Lactulose solution contains galactose.
Common Questions
Can I take lactulose with other medicines?
How long does it take for lactulose to work?
What should I do if I get diarrhea?
Can children take lactulose?
Does the color change of the medicine mean it has gone bad?
What do I do if the medicine freezes?
Can I mix lactulose with other liquids?
How will I know if the lactulose is working?
What if I still don't have a bowel movement?
Can I take lactulose if I am diabetic?
What are the common side effects of lactulose?
What drug class is lactulose?
Is lactulose safe during pregnancy?
Related Medications in Osmotic Laxative
Other drugs grouped near lactulose - same-class peers and common alternatives.
alosetron
Lotronex
Alosetron (Lotronex) is a medicine for women with severe diarrhea-predominant irritable bowel syndrome (IBS).
Compare with lactulose →
aprepitant
Emend
Aprepitant (Emend) is a medicine that helps prevent nausea and vomiting.
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bisacodyl
Dulcolax
Bisacodyl is a medicine that helps you have a bowel movement.
Compare with lactulose →
bismuth subsalicylate
Pepto-Bismol
Bismuth subsalicylate (Pepto-Bismol) is a medicine that can treat diarrhea and upset stomach.
Compare with lactulose →
cimetidine
Tagamet
Cimetidine (Tagamet) reduces stomach acid.
Compare with lactulose →
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What the FDA Data Shows for lactulose
The FDA label for lactulose (sold under brand names such as Enulose, Kristalose) classifies it as a prescription-only medication in the Osmotic Laxative class. This medicine treats and prevents portal-systemic encephalopathy. Official labeling lists 5 commonly reported side effects, including Gas, Bloating, Belching.
Post-market surveillance from the FDA Adverse Event Reporting System (FAERS) captures real-world experience. For this drug, FAERS contains 37,033 voluntary reports. Interaction data is drawn directly from FDA-approved prescribing information. NADAC pricing from CMS shows a generic unit cost of $0.01.
Report counts do not establish causation, a FAERS entry documents a temporal association, not proof that the drug produced the outcome. Widely prescribed medications naturally accumulate more reports than niche therapies, so raw totals must be interpreted alongside total exposure. Shortage status, recall history, and patent information further shape supply and switching decisions. This page summarizes public FDA data for educational purposes only and is not a substitute for professional medical advice, always consult a licensed healthcare provider before starting, stopping, or changing any medication.
Data Sources
Drug labeling: FDA Drug Labels (SPL/DailyMed). Adverse events: FDA Adverse Event Reporting System (FAERS). Pricing: CMS National Average Drug Acquisition Cost (NADAC).
FAERS reports are voluntary and do not establish causation. Drug interactions are derived from FDA labeling and clinical references. Always consult a healthcare professional before making medication decisions.
Last updated: June 1, 2022
Read our methodology - how this data is sourced, computed, and verified.
Data currency: FDA FAERS adverse-event reports through 2025, CMS NADAC acquisition-cost pricing effective December 2024, compiled and last refreshed May 2026. See our methodology for per-source dates and refresh cadence. Spot a figure that looks wrong? Report a correction.
All federal data sources used on this page
- FDA Orange Book - approved drug products with therapeutic equivalence. accessdata.fda.gov/cder/ob
- FDA DailyMed - NIH-hosted drug labeling for FDA-approved meds. dailymed.nlm.nih.gov
- FDA Adverse Event Reporting System (FAERS) - post-marketing safety surveillance. fda.gov/drugs/faers
- NLM RxNorm - standardized clinical drug nomenclature. nlm.nih.gov/research/umls/rxnorm
- CMS Medicare Part B Drug Average Sales Price Files - federal drug pricing data. cms.gov/medicare/part-b-drugs/asp
- FDA Drug Shortages Database - current and resolved drug shortage tracking. accessdata.fda.gov/drugshortages