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.
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
- Nausea
Nausea
2,524 reports
- Constipation
Constipation
2,497 reports
- Fall
Fall
2,241 reports
- Vomiting
Vomiting
2,047 reports
- Fatigue
Fatigue
2,027 reports
- Death
Death
1,939 reports
- Dyspnoea
Dyspnoea
1,910 reports
- Diarrhoea
Diarrhoea
1,892 reports
- Pain
Pain
1,711 reports
- Pneumonia
Pneumonia
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) 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?
What pregnancy or breastfeeding source fields are listed for lactulose?
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.
Compare with lactulose →
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 →
Compare beyond drug class
Nationwide peers by FAERS volume & death-report share
Two PlainMeds-derived comparison paths for lactulose: nearest FDA FAERS report volume and nearest death-report share among drugs with at least 1,000 logged reports, excluding same-class neighbors listed above. Counts reflect reporting volume, not proven individual harm.
Similar FAERS report volume
Nearest drugs by total FAERS reports. This record: 37,033.
Similar death-report share
Nearest drugs by FAERS death-report share. This record: 17.58%.
- bisacodyl Δ 0.08 pts · 13,500 reports · Stimulant Laxative 17.50%death share
- clozapine Δ 0.10 pts · 121,298 reports · Atypical Antipsychotic 17.68%death share
- chlorpheniramine Δ 0.16 pts · 6,221 reports · First-Generation Antihistamine 17.42%death share
- valganciclovir Δ 0.23 pts · 18,056 reports · Antiviral (Nucleoside Analog) 17.35%death share
Medication Guides
Understanding Drug Interactions
How CYP450 enzymes, inhibitors, and inducers affect your medications
Generic vs Brand Name Drugs
FDA requirements, cost savings, and when the difference matters
Narrow Therapeutic Index Drugs
FDA bioequivalence and label-record context for narrow therapeutic index medicines
Common Drug Interactions
Dangerous medication combinations and how to protect yourself
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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 are separate source-record fields. This page is a public FDA/CMS registry and does not provide medical, treatment, substitution, or medication-change directions.
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. This registry does not provide medication decisions.
Last updated: June 1, 2022
PlainMeds is rendered directly from FDA openFDA/FAERS extracts, DailyMed labels, and CMS drug-pricing files, no number is typed in by an editor. FAERS counts, recalls, shortages, and price figures on this page are queried live from those federal extracts. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of 2026-05-15. Primary sources: openFDA / FAERS, DailyMed and CMS Part B ASP.
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 from the source snapshot dated . See our methodology for per-source dates and refresh cadence. Spot a figure that looks wrong? Report a data issue.
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