What is Onfi used to treat?
Onfi (clobazam) is used in combination with other medicines for the treatment of seizures associated with Lennox-Gastaut syndrome (LGS) in patients 2 years of age or older.
Lennox-Gastaut syndrome (LGS) is a severe form of epilepsy that begins in early childhood and is characterized by different types of seizures and intellectual disability.
Onfi works by binding to GABA receptors in the central nervous system (the brain and nerves) and belongs to the benzodiazepine class of drugs. Researchers think it affects neurotransmitters in the brain that affect the way brain cells communicate.
Onfi is taken by mouth and comes as a 10 mg or 20 mg oral tablet or as a 2.5 mg/mL suspension. Your doctor will determine your dose.
Clobazam also come as an oral film known as Sympazam (containing 5 mg, 10 mg, or 20 mg of clobazam), indicated to treat Lennox-Gastaut syndrome in patients 2 years of age or older. It is place on the tongue and allowed to dissolve, according to the Epilepsy Foundation.
See What is the difference between Sympazan and Onfi? to learn more about these two forms of clobazam.
Why is Onfi a controlled substance?
Onfi is a Schedule IV controlled substance because it's active ingredient, clobazam, has the potential to be abused, misued or lead to dependence and addiction. Overdose and serious side effects including coma and death can occur with benzodiazepines, including clobazam.
Benzodiazepines can also lead to many withdrawal symptoms, with side effects like seizures, memory problems, muscle pain, nausea and vomiting and anxiety.
Tell your healthcare provider if you have ever abused or been dependent on alcohol, prescription medicines or street drugs.
Benzodiazepines like Onfi can cause severe drowsiness, breathing problems (respiratory depression), coma, and death when taken with alcohol, opioid (narcotic) medicines, street drugs, or other central nervous system depressants. Get emergency help right away (call 911) if any of these side effects occur: shallow or slowed breathing; breathing stops (which may lead to the heart stopping); excessive sleepiness (sedation).
Onfi may also lead to extreme drowsiness, dizziness, and impaired motor skills. Do not drink alcohol or take other drugs that may make you sleepy or dizzy while taking Onfi until you talk to your doctor. Onfi can worsen your sleepiness or dizziness when taken with alcohol or drugs that cause sleepiness or dizziness.
If you take too much Onfi, call your healthcare provider, call 911 or go to the nearest hospital emergency room right away
This drug should be discontinued slowly to avoid triggering a seizure or withdrawal symptoms. Do NOT stop taking Onfi unless you have spoken with your doctor first.
Do not drive, operate heavy machinery, or do other dangerous activities until you know how Onfi affects you.
Keep Onfi in a secure place to prevent misuse and abuse. Selling or giving away Onfi may harm others, and is against the law.
To review potential drug interactions, check Onfi drug interactions here.
What are common side effects with Onfi?
The most common side effects associated with Onfi treatment include:
- sleepiness
- drooling
- constipation
- cough
- pain with urination
- fever
- acting aggressive, being angry, or violent
- feeling tired
- difficulty sleeping
- problems with breathing
- slurred speech
Serious skin reactions can occur when Onfi is taken with other medicines. In addition, a serious allergic reaction can occur that may affect your skin or other parts of your body such as your liver, kidneys, heart, or blood cells.
Call your healthcare provider immediately or get emergency medical help if you have skin blisters, rash, sores in the mouth, hives, dark urine, fever or swollen glands that do not go away, swelling in your face, trouble breathing, yellowing of the skin or the whites of the eyes.
Do NOT stop taking Onfi or change your dose without your doctor’s approval. If you stop Onfi suddenly, your seizures may worsen or not stop (status epilepticus), you may hear or see things that are not there (hallucinations), lose touch with reality, have shaking, nervousness and muscle and stomach cramps, increase in activity or talking, depression, or have suicidal thoughts or actions. If you experience these side effects, Call your healthcare provider or go to the nearest hospital emergency room right away.
Onfi may cause suicidal thoughts or actions in a very small number of people, in about 1 in 500.
These are not all the possible side effects with Onfi. More common and serious side effects and warnings are also outlined in the package labeling and Patient Medication Guide. Call your doctor for medical advice about side effects or warnings with Onfi.
Review: Onfi side effects and warnings (in more detail)
Related questions
- How much does Onfi cost without insurance?
- Does Onfi cause weight gain?
- What is the difference between Sympazan and Onfi?
How quickly does Onfi work?
Onfi is quickly absorbed into your bloodstream after you take it. It reaches a peak within 30 minutes to 4 hours, but it takes about 7 to 9 days of dosing for the Onfi parent drug (clobazam) to reach a steady state level in the body.
Steady state is the time during which the drug levels in the body stays consistent. In other words, steady state is when the rate of the drug going into your body is equal to the rate of drug leaving your body (elimination).
The active metabolite N-desmethylclobazam has one-fifth of the activity of the parent drug clobazam, and takes about 2 to 3 weeks to reach steady state.
It may take some time for your doctor to find the dose of Onfi that works best for you.
Although steady state levels are typically reached within 1 to 3 weeks, clinical effectiveness with Onfi can vary from person to person and may take longer due to unique factors such as age, weight, amount of body fluid, additional medications you take, kidney or liver function, or other medical conditions. Ask your doctor how quickly Onfi might work for you, or your child's, condition.
Taking Onfi tablets or liquid with food or the tablets crushed in applesauce does not affect how well it is absorbed into your body.
Key Takeaways
Onfi (clobazam) is used in combination with other medicines for the treatment of seizures associated with Lennox-Gastaut syndrome (LGS) in patients 2 years of age or older. Lennox-Gastaut syndrome (LGS) is a severe form of epilepsy that begins in early childhood and is characterized by different types of seizures and intellectual disability.
Onfi works by binding to GABA receptors in the central nervous system (the brain and nerves) and belongs to the benzodiazepine class of drugs. It is a CIV controlled substance.
Onfi is manufactured by Lundbeck.
This is not all the information you need to know about Onfi (clobazam) for safe and effective use and does not replace your doctor's instructions. Review the full product information and discuss this information and any questions you have with your doctor or other health care provider.
References
- Onfi (clobazam). Medication Guide. Lundbeck. Deerfield, IL. Accessed Aug 22, 2025 at https://www.lundbeck.com/content/dam/lundbeck-com/americas/united-states/products/neurology/onfi_mg_us_en.pdf
- Onfi (clobazam). Prescription labeling. Lundbeck. Deerfield, IL. Accessed Aug 22, 2025 at https://www.lundbeck.com/content/dam/lundbeck-com/americas/united-states/products/neurology/onfi_pi_us_en.pdf
- Epilepsy Foundation. Clobazam. Updated Updated: 10/17/2023. Accessed Aug 22, 2025 at https://www.epilepsy.com/medications/clobazam
Read next
What type of epilepsy is Diacomit used to treat?
Diacomit (stiripentol) is an oral anticonvulsant used with clobazam (Onfi) for seizures associated with Dravet syndrome in patients 6 months of age and older, weighing at least 7 kg (15.4 lbs), and taking the benzodiazepine clobazam (Onfi). Diacomit is not used alone to treat Dravet Syndrome, a rare, genetic form of epilepsy. It usually begins in infancy, often during a fever due to illness or vaccination. Continue reading
How long does it take for Lyrica (pregabalin) to work?
In clinical studies with Lyrica, some patients experienced a decrease in pain as early as the first week, which persisted during the entire study period of 5 to 13 weeks. Continue reading
How long does Lyrica (pregabalin) stay in your system?
Lyrica (pregabalin) will stay in your blood (plasma) for about 35 hours, but its clinical effect may wear off before this time. Studies have shown pregabalin to be detectable in urine for up to 5 to 6 days. Continue reading
See also:
Related medical questions
- Lyrica vs Gabapentin: What's the difference?
- Can you stop Lyrica (pregabalin) cold turkey?
- How effective is Topamax (topiramate) for weight loss?
- CBD Oil: What are 9 Proven or Possible Health Benefits?
- Does Lyrica (pregabalin) make you sleepy?
- Is gabapentin addictive?
- Should gabapentin be taken with food?
- What not to take with topiramate?
- Can you stop taking Topamax suddenly?
- Does Topamax (topiramate) cause hair loss?
- Can you drink alcohol while taking Topamax (topiramate)?
- How long does it take for Topamax to start working?
- How long does Topamax stay in your system?
- How long does Trileptal withdrawal last?
- How long does it take for Trileptal to work?
- Does Trileptal cause weight gain?
- What is the difference between Briviact and Keppra?
- Is Topamax (topiramate) a controlled substance?
- CBD vs THC vs Cannabis: What's the difference between them?
- How does Trokendi XR help with weight loss?
- Are Topamax and Trokendi XR the same thing?
- Aptiom vs Keppra, what is the difference?
- Can Briviact be cut in half or crushed?
- Is Oxtellar XR the same as Trileptal?
- When is the best time of day to take Trokendi XR?
- How long does it take for Oxtellar XR to work?
- Can Fycompa cause hair loss?
Drug information
- Onfi Information for Consumers
- Onfi prescribing info & package insert (for Health Professionals)
- Side Effects of Onfi (detailed)
- Onfi user reviews (11)
Related support groups
- Onfi (5 questions, 12 members)
- Epilepsy (94 questions, 413 members)
- Seizures (162 questions, 795 members)
- Lennox-Gastaut Syndrome (13 questions, 10 members)