entacapone Side Effects
Also known as: Comtan
Analysis of 3,955 adverse event reports submitted to the FDA from 2003 to 2025.
Total Reports
3,955
Death-Related
603
15.2% of reports
Hospitalizations
1,340
33.9% of reports
Top Indication
Parkinson^S Disease
Most Reported Adverse Reactions
Who Reports Side Effects
Gender Distribution
Age Distribution
Reporting Trend by Year
Reactions in Death Reports
Top reactions reported in 603 reports where death was an outcome. These are voluntarily reported and do not establish causation.
| Reaction | Reports |
|---|---|
| DEATH | 318 |
| PARKINSON^S DISEASE | 88 |
| HALLUCINATION | 74 |
| FALL | 71 |
| PNEUMONIA | 45 |
| DYSKINESIA | 44 |
| CONFUSIONAL STATE | 42 |
| AGITATION | 35 |
| DEMENTIA | 25 |
| HYPONATRAEMIA | 25 |
| CARDIAC ARREST | 24 |
| DRUG INEFFECTIVE | 24 |
| ASTHENIA | 23 |
| GENERAL PHYSICAL HEALTH DETERIORATION | 23 |
| OFF LABEL USE | 22 |
| ORTHOSTATIC HYPOTENSION | 22 |
| URINARY RETENTION | 21 |
| DYSPHAGIA | 20 |
| MYOCARDIAL INFARCTION | 20 |
| CONSTIPATION | 19 |
Reactions in Hospitalization Reports
Top reactions in 1,340 reports where hospitalization was an outcome.
| Reaction | Reports |
|---|---|
| FALL | 238 |
| DYSKINESIA | 195 |
| HALLUCINATION | 159 |
| CONFUSIONAL STATE | 120 |
| ON AND OFF PHENOMENON | 105 |
| PARKINSON^S DISEASE | 102 |
| GAIT DISTURBANCE | 97 |
| URINARY TRACT INFECTION | 88 |
| MUSCLE RIGIDITY | 87 |
| TREMOR | 84 |
| ASTHENIA | 83 |
| PSYCHOTIC DISORDER | 74 |
| PNEUMONIA | 73 |
| AGITATION | 68 |
| HALLUCINATION, VISUAL | 67 |
| DRUG INEFFECTIVE | 66 |
| FATIGUE | 65 |
| THERAPEUTIC PRODUCT EFFECT INCOMPLETE | 64 |
| DYSTONIA | 63 |
| MOBILITY DECREASED | 63 |
Nearby — Related Medications
What the FAERS Data Reveals About entacapone Side Effects
The FDA Adverse Event Reporting System (FAERS) contains 3,955 voluntary reports linked to entacapone and its brand equivalents (Comtan), spanning 2003 through 2025. Of those, 603 (15.2%) listed death as an outcome and 1,340 (33.9%) involved hospitalization. The most common indication reported alongside adverse events was Parkinson^S Disease.
Demographic breakdowns help contextualize who is being exposed to the drug. Of reports with known sex, 34% were female and 66% male; age distribution skews toward 65-74, with 1,011 reports in that bracket. The single most reported reaction is dyskinesia with 461 submissions, followed by hallucination 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.