Clobazam (Onfi)

What it treats

Clobazam is approved by the U.S. Food and Drug Administration as adjunctive treatment of seizures associated with Lennox-Gastaut syndrome in patients 2 years of age and older. Off-label, it is sometimes used for other refractory epilepsies including Dravet syndrome.

Outside of epilepsy, clobazam is not commonly prescribed in the U.S. In some countries it has an anxiety indication, but that role in the U.S. is filled by other benzodiazepines and non-benzodiazepine options.

How it works

Clobazam is a 1,5-benzodiazepine, which is a slight structural twist compared with the more familiar 1,4-benzodiazepines (like alprazolam and diazepam). It strengthens the effect of GABA at the GABA-A receptor, but with a preference for the α2 subunit-containing receptors that mediate anxiolytic and anti-seizure effects, and less activity at the α1 subunits that mediate sedation.

The practical result is less sedation for the same anti-seizure benefit compared with older benzodiazepines. That matters when the medication is being used every day, often in children.

Receptor mechanism (detail)

Clobazam is a positive allosteric modulator at the GABA-A receptor with relative α2 selectivity. That subunit preference is what gives it a somewhat different clinical profile from other benzodiazepines: solid anti-seizure activity with less sedation than diazepam or clonazepam. Its main active metabolite, N-desmethylclobazam, is long-acting and carries much of the effect over time. Metabolism runs through CYP3A4 and CYP2C19, so CYP2C19 poor metabolizers accumulate the active metabolite and may need lower doses.

Potency and typical dosing pattern

Ranges are typical framework only, not a prescription for any individual.

Adults and children over 30 kg: 5 mg twice daily starting, titrated over 1 to 2 weeks to 20 mg twice daily. Children 30 kg or less: half those doses. Adjust downward in older adults, hepatic impairment, or CYP2C19 poor metabolizers.

Safety monitoring

• Sedation. Less than with older benzodiazepines, but still present.
• Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN). Rare but serious skin reactions have been reported. Any new rash, especially with fever or mucous membrane involvement, is a reason to stop and get evaluated urgently.
• Suicidal thoughts and behaviors. Antiepileptic drugs as a class carry this class-level warning.
• Dependence and withdrawal with regular use.
• Respiratory depression with opioids or alcohol (FDA boxed warning).
• CYP2C19 poor metabolizers may need lower doses because of higher active metabolite levels.
• Do not stop abruptly. Rebound seizures and withdrawal.

What to expect

Common side effects

• Drowsiness and sedation.
• Constipation.
• Drooling (particularly in children).
• Aggression or irritability in some children.
• Coordination problems and unsteadiness.
• Difficulty swallowing.
• Fever.

If any of these are marked or persistent, the prescriber should hear about it.

Serious side effects and warnings

Boxed warning: dependence and withdrawal. Benzodiazepines carry an FDA boxed warning about abuse, misuse, addiction, physical dependence, and withdrawal.

Boxed warning: combining with opioids. Benzodiazepines and opioids together can cause profound sedation, slowed breathing, coma, and death.

• Stevens-Johnson syndrome and toxic epidermal necrolysis. Rare, potentially fatal skin reactions. A new rash, particularly with mucous membrane involvement or fever, means stop the medication and seek urgent care.
• Suicidal thoughts. Antiepileptic drug class warning. New or worsening depression or suicidal thinking needs prescriber contact.
• Respiratory depression with other CNS depressants.
• Withdrawal seizures with abrupt discontinuation. Taper only under supervision.
• Falls in older adults and cognitive effects.
• Pediatric behavior. Some children develop aggression or irritability. A dose or medication change may be needed.

Sexual side effects

Clobazam isn't particularly associated with sexual side effects. If a change occurs, tell the prescriber.

Weight, appetite, and sleep

Clobazam doesn't typically cause meaningful weight change. Sedation can affect daytime energy. Sleep is generally not a primary target with clobazam; the goal is seizure control.

Starting and dosing basics

This section is general background, not a dosing instruction for any individual. The right dose is a decision for a prescriber.

Clobazam comes as tablets and an oral suspension, which is often useful in children who can't swallow tablets. Doses are given twice daily.

Missed doses and interactions

If a dose is missed, take it as soon as remembered unless it's close to the next dose. Don't double up. CYP3A4 and CYP2C19 interactions matter: strong CYP2C19 inhibitors (fluvoxamine, omeprazole, some SSRIs) raise the active metabolite. Alcohol and other sedatives compound drowsiness. Give every prescriber and pharmacist the full medication list.

Stopping and tapering

Clobazam should not be stopped abruptly. Withdrawal can include rebound seizures, anxiety, agitation, and in serious cases seizures. The taper is a prescriber's decision, usually over weeks.

Pregnancy and breastfeeding

Antiepileptic decisions in pregnancy involve balancing seizure control against fetal risk. Benzodiazepines including clobazam are generally used cautiously and only when needed. Anyone pregnant, planning a pregnancy, or breastfeeding should have this discussion with the treating clinician, ideally before pregnancy.

Cost and generic availability

Clobazam is available as generic (tablets and oral suspension) as well as brand-name Onfi. Most insurance covers it. The oral suspension may be more expensive; a pharmacist can help with formulary questions.

Common questions

How is clobazam different from other benzodiazepines? It's structurally a 1,5-benzodiazepine, not a 1,4-benzodiazepine like alprazolam or diazepam. It has a preference for the GABA-A α2 subunit, which is where anti-seizure and anti-anxiety effects come from, and less activity at α1, which mediates sedation. That gives it a less sedating profile at seizure-controlling doses.

What should I do about a new rash? Stop the medication and contact the prescriber urgently. A new rash, especially with fever, mouth or eye involvement, or spreading, could be Stevens-Johnson syndrome or toxic epidermal necrolysis, both of which are medical emergencies.

Is clobazam addictive? It carries the class-level risk of physical dependence. Regular use over weeks builds tolerance and can produce withdrawal on stopping. Because it's used for seizures, stopping abruptly is doubly dangerous: withdrawal plus seizure rebound.

Can I drink alcohol while taking it? No. Alcohol adds to sedation and to seizure risk if stopped abruptly.

Questions to ask your prescriber

• Why is clobazam the right add-on for my (or my child's) seizures?
• What should I watch for as we titrate the dose?
• How would we know if a rash is a serious reaction?
• If I need surgery or a procedure, how do we manage clobazam around it?
• If we ever want to stop clobazam, how do we taper?

Sources

This guide draws on current prescribing information and public health references. It is reviewed for clinical accuracy and updated as guidance changes and current as of June 8, 2026.

• U.S. Food and Drug Administration. Clobazam (Onfi) prescribing information.
• MedlinePlus, U.S. National Library of Medicine. Clobazam.
• American Epilepsy Society. Practice guidance on Lennox-Gastaut syndrome.
• International League Against Epilepsy. Treatment recommendations.
• National Institute for Health and Care Excellence (NICE). NG215, Medicines associated with dependence or withdrawal symptoms.