Prescription medication · Benzodiazepine (Anticonvulsant)
clobazam
Also sold as Onfi, Sympazan. Clobazam oral suspension is used to treat seizures in people 2 years and older who have Lennox-Gastaut syndrome (LGS).
Data updated 2026-05-15
- 23,107
- FDA reportsModerately reported
- 6
- InteractionsFew interactions
- 99% less
- Generic vs brandHuge savings
- 1
- Recall record
What the data shows
clobazam (Onfi) is a prescription Benzodiazepine (Anticonvulsant), reported at a middle-of-the-pack volume (23,107 FDA reports), whose generic costs a fraction of the brand (about 99% less).
Reporting volume reflects how widely a drug is used and studied, not how dangerous it is, a FAERS report documents a temporal association, never proof of cause.
clobazam (Onfi) is a prescription Benzodiazepine (Anticonvulsant). Clobazam oral suspension is used to treat seizures in people 2 years and older who have Lennox-Gastaut syndrome (LGS).
Clobazam oral suspension is a medicine used with other medicines to treat seizures caused by Lennox-Gastaut syndrome. It is a type of drug called a benzodiazepine.
Verify with FDA → · CMS NADAC pricing →
Drug Pricing (NADAC)
Brand Price
$28.58/unit
Generic Price
$0.24/unit
Generic Savings
99%
Generic Available
Yes (15 manufacturers)
Pricing data from NADAC (CMS), effective December 18, 2024. Compare all drug costs →
What it does
Clobazam oral suspension is used to treat seizures in people 2 years and older who have Lennox-Gastaut syndrome (LGS).
Common side effects
Constipation, Sleepiness or drowsiness, Fever
Key warnings
Clobazam can cause serious side effects: * **Risk of Using with Opioids:** Taking clobazam with opioid medicines can cause severe sleepiness, slowed breathing, coma, and death.
The sections below are summarized in plain English from clobazam's FDA-approved prescribing information. They describe what the official label says, and are not personal medical advice.
How It Works
Clobazam belongs to a class of drugs called benzodiazepines. It works by affecting certain chemicals in the brain that may be unbalanced in people with seizures. This helps to reduce the frequency of seizures.
How to Take It
Take clobazam oral suspension as your doctor tells you. If your daily dose is more than 5 mg, take it in two divided doses. You can take it with or without food. Use the provided syringe to measure your dose. Shake the bottle well before each use.
This is a plain-language summary of clobazam's FDA labeling, not individualized dosing advice. Ask a pharmacist or prescriber before changing how you take this medication.
Pregnancy & Breastfeeding
Clobazam may harm your unborn baby. If you are pregnant or plan to become pregnant, talk to your doctor. There is a pregnancy registry for women who take anti-epilepsy drugs like clobazam. You can enroll by calling 1-888-233-2334.
This is a plain-language summary of clobazam'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 almost time for your next dose, skip the missed dose and take your next dose at the regular time.
This is a plain-language summary of clobazam's FDA labeling, not individualized advice. Ask a pharmacist or prescriber what to do about your specific missed dose.
Storage
Store clobazam oral suspension in its original bottle in an upright position at room temperature (68°F to 77°F).
Side Effects (from patient reports)
Based on 23,107 FDA adverse event reports.
Most-reported reactions
Adverse reactions in FAERS for clobazam, by number of reports
- Seizure
Seizure
4,619 reports
- Sleepiness 1,798
Sleepiness
1,798 reports
- Medicine interaction 1,123
Medicine interaction
1,123 reports
- Tiredness 1,090
Tiredness
1,090 reports
- Epilepsy 805
Epilepsy
805 reports
- Condition worsened 794
Condition worsened
794 reports
- Prolonged seizure 698
Prolonged seizure
698 reports
- Pneumonia 663
Pneumonia
663 reports
- Fall 630
Fall
630 reports
- Aggression 622
Aggression
622 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 clobazam 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 clobazam sits
clobazam has more FDA adverse-event reports than 58% 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 clobazam; the line is the median (50th percentile).
FDA Adverse Event Report Analysis
Detailed analysis of 23,107 reports from the FDA Adverse Event Reporting System (FAERS). Reports span 2002–2025.
Total Reports
23,107
Reports Mentioning Death
1,511
6.5% of reports — not proof of cause
Hospitalization Reports
7,829
Top Indication
Product Used For Unknown Indication
Gender Distribution
Age Distribution
Most Reported Adverse Reactions (FAERS)
| # | Reaction | Reports |
|---|---|---|
| 1 | SEIZURE | 4,619 |
| 4 | SOMNOLENCE | 1,798 |
| 5 | DRUG INTERACTION | 1,123 |
| 6 | FATIGUE | 1,090 |
| 7 | EPILEPSY | 805 |
| 8 | CONDITION AGGRAVATED | 794 |
| 9 | STATUS EPILEPTICUS | 698 |
| 11 | PNEUMONIA | 663 |
| 12 | FALL | 630 |
| 13 | AGGRESSION | 622 |
| 14 | DECREASED APPETITE | 607 |
| 15 | DIARRHOEA | 598 |
| 16 | GENERALISED TONIC-CLONIC SEIZURE | 595 |
| 17 | VOMITING | 584 |
| 18 | MULTIPLE-DRUG RESISTANCE | 544 |
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
Clobazam can cause serious side effects: * **Risk of Using with Opioids:** Taking clobazam with opioid medicines can cause severe sleepiness, slowed breathing, coma, and death. Only take them together if no other treatment works, and use the lowest dose for the shortest time. * **Risk of Abuse, Misuse, and Addiction:** Clobazam can be abused, misused, and lead to addiction, overdose or death. Your doctor will assess your risk before and during treatment. * **Risk of Dependence and Withdrawal:** Taking clobazam can lead to physical dependence. Stopping it suddenly can cause life-threatening withdrawal symptoms. To stop, your doctor will slowly lower your dose.
Known Drug Interactions
7.2 Effect of EPIDIOLEX on Other Drugs Antiepileptic Drugs Clobazam Concomitant use of EPIDIOLEX with clobazam increases plasma concentrations of N‑desmethylclobazam, the active metabolite of clobazam [see Clinical Pharmacology ( 12.3 )], which may increase the risk of clobazam-related adverse reactions [see Adverse Reactions ( 6.1 ) and Warnings and Precautions ( 5.1 , 5.2 )]. Consider a reduction in dosage of clobazam if adverse reactions known to occur with clobazam are experienced when concomitantly used with EPIDIOLEX.
Mechanism: Cannabidiol increases the amount of an active byproduct of clobazam in your blood, which can lead to more side effects.
What to do: If you experience increased side effects, your doctor may need to reduce your dose of clobazam.
( 7.1 ) Phenobarbital and Clobazam: Reduce dosage as needed when used concomitantly with XCOPRI. phenobarbital ↑ plasma concentrations Because of a potential for an increase in the risk of adverse reactions from these drugs, consider a reduction in dosage of phenobarbital or clobazam, as clinically appropriate, when used concomitantly with XCOPRI. desmethylclobazam, the active metabolite of clobazam ↑ plasma concentrations CYP2B6 Substrates ↓ plasma concentrations Because of a potential for reduced efficacy of these drugs, increase the dosage of CYP2B6 or CYP3A4 substrates, as needed, when...
Mechanism: Cenobamate increases the level of the active part of clobazam in your bloodstream. This can lead to more side effects from the clobazam.
What to do: Your doctor should consider lowering your clobazam dose if you are taking both of these medications.
Dosage adjustment of clobazam oral suspension may be necessary when co-administered with strong CYP2C19 inhibitors (e.g., fluconazole, fluvoxamine, ticlopidine) or moderate CYP2C19 inhibitors (e.g., omeprazole) [see Clinical Pharmacology ( 12.3 )].
Mechanism: Omeprazole slows down the liver's ability to process clobazam. This can cause the amount of clobazam in your body to rise to higher levels.
What to do: Your doctor may need to lower your clobazam dose while you are taking omeprazole. Watch for increased side effects like extreme sleepiness.
Dosage adjustment of clobazam oral suspension may be necessary when co-administered with strong CYP2C19 inhibitors (e.g., fluconazole, fluvoxamine, ticlopidine) or moderate CYP2C19 inhibitors (e.g., omeprazole) [see Clinical Pharmacology ( 12.3 )].
Mechanism: Fluconazole blocks the specific enzyme that clears clobazam from your system. This makes the clobazam stay in your body longer and can increase its effects.
What to do: Your healthcare provider may need to adjust your clobazam dosage. Let your doctor know if you feel more tired or dizzy than usual.
Dosage adjustment of clobazam oral suspension may be necessary when co-administered with strong CYP2C19 inhibitors (e.g., fluconazole, fluvoxamine, ticlopidine) or moderate CYP2C19 inhibitors (e.g., omeprazole) [see Clinical Pharmacology ( 12.3 )].
Mechanism: Fluvoxamine interferes with how your body breaks down clobazam. This can lead to a buildup of clobazam in your bloodstream.
What to do: Your doctor might need to change your dose of clobazam to keep it at a safe level. Monitor yourself for increased drowsiness or trouble with coordination.
This is a plain-language summary of interactions documented in FDA labeling, not individualized advice. Ask a pharmacist or prescriber before combining medications.
Common Questions
Can I drink alcohol while taking clobazam?
What should I do if I have a rash while taking clobazam?
Can clobazam cause suicidal thoughts?
How long does it take for clobazam to start working?
Can I stop taking clobazam suddenly?
Does clobazam interact with birth control pills?
What should I do if my child is too sleepy while taking clobazam?
How long can I use the bottle of oral suspension after opening it?
What should I do if I lose the oral syringe?
Can clobazam cause problems with breathing?
What are the common side effects of clobazam?
Does clobazam interact with other medications?
What drug class is clobazam?
Is there a generic version of clobazam?
Is clobazam safe during pregnancy?
Has clobazam been recalled?
Active Recalls
Presence of Foreign Tablets/Capsules
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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
Why some drugs demand precise dosing and monitoring
Common Drug Interactions
Dangerous medication combinations and how to protect yourself
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What the FDA Data Shows for clobazam
The FDA label for clobazam (sold under brand names such as Onfi, Sympazan) classifies it as a prescription-only medication in the Benzodiazepine (Anticonvulsant) class. Clobazam oral suspension is used to treat seizures in people 2 years and older who have Lennox-Gastaut syndrome (LGS). Official labeling lists 5 commonly reported side effects, including Constipation, Sleepiness or drowsiness, Fever.
Post-market surveillance from the FDA Adverse Event Reporting System (FAERS) captures real-world experience. For this drug, FAERS contains 23,107 voluntary reports. The database also lists 6 documented drug interactions derived from FDA labeling, with the top-flagged interaction rated moderate severity. NADAC pricing from CMS shows a generic unit cost of $0.24 versus $28.58 for the brand - a 99% generic savings.
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 (currently 1 recall record on file), 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: December 27, 2024
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