lactulose Side Effects
Also known as: Enulose, Kristalose
Analysis of 37,033 adverse event reports submitted to the FDA from 1997 to 2025.
Total Reports
37,033
Death-Related
6,511
17.6% of reports
Hospitalizations
20,384
55.0% of reports
Top Indication
Product Used For Unknown Indication
Most Reported Adverse Reactions
Who Reports Side Effects
Gender Distribution
Age Distribution
Reporting Trend by Year
Reactions in Death Reports
Top reactions reported in 6,511 reports where death was an outcome. These are voluntarily reported and do not establish causation.
| Reaction | Reports |
|---|---|
| DEATH | 1,932 |
| PNEUMONIA | 487 |
| SEPSIS | 377 |
| DYSPNOEA | 362 |
| NAUSEA | 342 |
| ASTHENIA | 312 |
| VOMITING | 298 |
| HEPATIC FAILURE | 291 |
| CONSTIPATION | 284 |
| DIARRHOEA | 269 |
| RENAL FAILURE | 269 |
| RESPIRATORY FAILURE | 252 |
| CARDIAC ARREST | 249 |
| OFF LABEL USE | 240 |
| ABDOMINAL PAIN | 237 |
| DISEASE PROGRESSION | 236 |
| HYPOTENSION | 234 |
| GENERAL PHYSICAL HEALTH DETERIORATION | 230 |
| HEPATIC ENCEPHALOPATHY | 224 |
| ACUTE KIDNEY INJURY | 223 |
Reactions in Hospitalization Reports
Top reactions in 20,384 reports where hospitalization was an outcome.
| Reaction | Reports |
|---|---|
| FALL | 1,819 |
| CONSTIPATION | 1,698 |
| NAUSEA | 1,505 |
| PNEUMONIA | 1,422 |
| VOMITING | 1,368 |
| HYPOTENSION | 1,319 |
| DYSPNOEA | 1,288 |
| PAIN | 1,150 |
| DIARRHOEA | 1,050 |
| CONFUSIONAL STATE | 1,044 |
| PYREXIA | 1,031 |
| FATIGUE | 991 |
| ANAEMIA | 890 |
| ABDOMINAL PAIN | 886 |
| ASTHENIA | 851 |
| BALANCE DISORDER | 823 |
| ACUTE KIDNEY INJURY | 798 |
| OFF LABEL USE | 787 |
| URINARY TRACT INFECTION | 767 |
| ORTHOSTATIC HYPOTENSION | 746 |
Nearby — Related Medications
What the FAERS Data Reveals About lactulose Side Effects
The FDA Adverse Event Reporting System (FAERS) contains 37,033 voluntary reports linked to lactulose and its brand equivalents (Enulose, Kristalose), spanning 1997 through 2025. Of those, 6,511 (17.6%) listed death as an outcome and 20,384 (55.0%) involved hospitalization. The most common indication reported alongside adverse events was Product Used For Unknown Indication.
Demographic breakdowns help contextualize who is being exposed to the drug. Of reports with known sex, 52% were female and 48% male; age distribution skews toward 45-64, with 9,655 reports in that bracket. The single most reported reaction is nausea with 2,524 submissions, followed by constipation and fall.
FAERS is a signal-detection tool, not a scorecard. Reports are voluntary, and a single case may list multiple suspect drugs, so numbers above should not be read as incidence rates or per-patient risk. Widely prescribed drugs naturally accumulate more reports than niche therapies even when individual risk is low. These aggregates are useful for spotting patterns that merit further pharmacovigilance, not for choosing between medications. This page is for educational reference only and is not medical advice — speak with a licensed clinician about any side-effect concerns.
Read our methodology — how this data is sourced, computed, and verified.