Drug side effects
clobazam Side Effects
The reactions most often reported to the FDA for clobazam (also sold as Onfi, Sympazan), with demographics, serious outcomes, and reporting trends.
Data updated 2026-05-15
- 23,107
- FAERS reports
Data from the FDA Adverse Event Reporting System (FAERS), 2002 to 2025. A FAERS report records a temporal association, not proof of cause. See our methodology for how figures are compiled and de-duplicated.
The most commonly reported side effects of clobazam come from 23,107 reports to the FDA, broken down here by frequency, patient demographics, and serious outcomes.
This page analyzes 23,107 reports to the FDA Adverse Event Reporting System (FAERS) for clobazam (Onfi): the reactions reported most often, who reported them, serious outcomes such as hospitalization, and year-over-year trends. A FAERS report does not prove the drug caused the effect, and report volume tracks how widely a drug is used, not how likely an effect is for any one person. Educational information, not medical advice.
Total Reports
23,107
Reports Mentioning Death
1,511
6.5% of reports — not proof the medicine caused the death
Hospitalizations
7,829
33.9% 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 1,511 reports where death was an outcome. These are voluntarily reported and do not establish causation.
| Reaction | Reports |
|---|---|
| DEATH | 439 |
| TOXICITY TO VARIOUS AGENTS | 147 |
| CARDIAC ARREST | 107 |
| SEIZURE | 98 |
| RESPIRATORY FAILURE | 87 |
| PNEUMONIA | 83 |
| STATUS EPILEPTICUS | 79 |
| COMPLETED SUICIDE | 75 |
| METABOLIC ACIDOSIS | 75 |
| SOMNOLENCE | 71 |
| SUDDEN UNEXPLAINED DEATH IN EPILEPSY | 69 |
| ARRHYTHMIA | 61 |
| OVERDOSE | 57 |
| GENERAL PHYSICAL HEALTH DETERIORATION | 53 |
| SEPSIS | 53 |
| MULTIPLE-DRUG RESISTANCE | 52 |
| COMA | 51 |
| RESPIRATORY DISTRESS | 51 |
Reactions in Hospitalization Reports
Top reactions in 7,829 reports where hospitalization was an outcome.
| Reaction | Reports |
|---|---|
| SEIZURE | 1,647 |
| SOMNOLENCE | 600 |
| PNEUMONIA | 517 |
| DRUG INTERACTION | 495 |
| STATUS EPILEPTICUS | 398 |
| HOSPITALISATION | 352 |
| PYREXIA | 349 |
| EPILEPSY | 337 |
| FALL | 310 |
| VOMITING | 305 |
| TOXICITY TO VARIOUS AGENTS | 287 |
| CONDITION AGGRAVATED | 285 |
| FATIGUE | 250 |
| GENERALISED TONIC-CLONIC SEIZURE | 232 |
| DECREASED APPETITE | 201 |
| DIARRHOEA | 198 |
Nearby, Related Medications
What the FAERS Data Reveals About clobazam Side Effects
The FDA Adverse Event Reporting System (FAERS) contains 23,107 voluntary reports linked to clobazam and its brand equivalents (Onfi, Sympazan), spanning 2002 through 2025. Of those, 1,511 (6.5%) listed death as an outcome and 7,829 (33.9%) 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, 51% were female and 48% male; age distribution skews toward 0-17, with 5,637 reports in that bracket. The single most reported reaction is seizure with 4,619 submissions, followed by somnolence and drug interaction.
How to read these numbers
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.
Drugs With a Similar FAERS Report Volume
Other medications with a total FDA adverse-event report count closest to clobazam's 23,107.
Read our methodology - how this data is sourced, computed, and verified.