Last updated on RxList: 7/16/2021
Onfi Side Effects Center

What Is Onfi?

Onfi (clobazam) is a benzodiazapine for use as an add-on treatment for seizures associated with Lennox-Gastaut syndrome (LGS) in patients 2 years of age or older.

What Are Side Effects of Onfi?

Side effects of Onfi include:

Serious side effects of Onfi include suicidal behavior. Tell your doctor if this occurs.

Dosage for Onfi

Onfi is available in 5 mg, 10 mg, and 20 mg strengths and can be administered whole, or crushed and mixed in applesauce. Dosing depends on body weight. It is important that people taking Onfi not drive, operate heavy machinery, or engage in other dangerous activities. Onfi can cause abuse and dependence and should not be used with alcohol. Abrupt discontinuation of Onfi should be avoided. The risk of withdrawal symptoms (for example, seizures, tremors, anxiety) is greater with higher doses.

What Drugs, Substances, or Supplements Interact with Onfi?

Onfi may interact with other medicines that make you sleepy (such as cold or allergy medicines, other sedatives, narcotics, sleeping pills, muscle relaxers, and medicines for seizures, depression, or anxiety), cimetidine, fluvastatin, indomethacin, probenecid, ropinirole, tamsulosin, terbinafine, ticlopidine, tolterodine, felbamate, oxcarbazepine, lansoprazole, omeprazole, ADHD medications, antidepressants, antifungals, anti-malaria medications, cancer medicines, cough medicines, heart or blood pressure medications, HIV/AIDS medications, or medicines to treat psychiatric disorders. Tell your doctor all medications and supplements you use.

Onfi During Pregnancy and Breastfeeding

Onfi may compromise the effectiveness of some birth control medications. Women should tell their healthcare providers if they are pregnant, planning to become pregnant, or are using birth control medications. Onfi may pass into breast milk and may harm a nursing baby. Consult your doctor before breastfeeding. Onfi may have harmful effects on unborn babies to include breathing and feeding problems, dangerously low body temperatures, and withdrawal symptoms. It is approved for children 2 years and older.

Additional Information

Our Onfi Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.


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Onfi Consumer Information

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Get emergency medical help if you have signs of an allergic reaction (hives, difficult breathing, swelling in your face or throat) or a severe skin reaction (fever, sore throat, burning eyes, skin pain, red or purple skin rash with blistering and peeling).

Report any new or worsening symptoms to your doctor, such as: mood or behavior changes, anxiety, panic attacks, trouble sleeping, or if you feel impulsive, irritable, agitated, hostile, aggressive, restless, hyperactive (mentally or physically), more depressed, or have thoughts about suicide or hurting yourself.

Clobazam can slow or stop your breathing, especially if you have recently used an opioid medication, alcohol, or other drugs that can slow your breathing. A person caring for you should seek emergency medical attention if you have weak or shallow breathing, if you are hard to wake up, or if you stop breathing.

Call your doctor at once if you have:

  • severe drowsiness, feeling like you might pass out;
  • unusual changes in mood or behavior;
  • aggression, thoughts of hurting yourself; or
  • problems with balance or muscle movement.

The sedative effects of clobazam may last longer in older adults. Accidental falls are common in elderly patients who take benzodiazepines. Use caution to avoid falling or accidental injury while you are taking clobazam.

Common side effects may include:

  • constipation;
  • drowsiness, lack of energy;
  • fever; or
  • drooling.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Read the entire detailed patient monograph for Onfi (Clobazam Tablets and Oral Suspension)


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Onfi Professional Information


Clinically significant adverse reactions that appear in other sections of the labeling include the following:

  • Risks from Concomitant Use with Opioids [see WARNINGS AND PRECAUTIONS]
  • Potentiation of Sedation from Concomitant Use with Central Nervous System Depressants [see WARNINGS AND PRECAUTIONS]
  • Somnolence or Sedation [see WARNINGS AND PRECAUTIONS]
  • Withdrawal Symptoms [see WARNINGS AND PRECAUTIONS]
  • Serious Dermatological Reactions [see CONTRAINDICATIONS, WARNINGS AND PRECAUTIONS]
  • Physical and Psychological Dependence [see WARNINGS AND PRECAUTIONS]
  • Suicidal Behavior and Ideation [see WARNINGS AND PRECAUTIONS]

Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.

During its development for the adjunctive treatment of seizures associated with LGS, ONFI was administered to 333 healthy volunteers and 300 patients with a current or prior diagnosis of LGS, including 197 patients treated for 12 months or more. The conditions and duration of exposure varied greatly and included single-and multiple-dose clinical pharmacology studies in healthy volunteers and two double-blind studies in patients with LGS (Study 1 and 2) [see Clinical Studies]. Only Study 1 included a placebo group, allowing comparison of adverse reaction rates on ONFI at several doses to placebo.

Adverse Reactions Leading To Discontinuation In An LGS Placebo Controlled Clinical Trial (Study 1)

The adverse reactions associated with ONFI treatment discontinuation in ≥1% of patients in decreasing order of frequency included lethargy, somnolence, ataxia, aggression, fatigue, and insomnia.

Most Common Adverse Reactions In An LGS Placebo Controlled Clinical Trial (Study 1)

Table 3 lists the adverse reactions that occurred in ≥5% of ONFI-treated patients (at any dose), and at a rate greater than placebo-treated patients, in the randomized, double-blind, placebo-controlled, parallel group clinical study of adjunctive AED therapy for 15 weeks (Study 1).

Table 3: Adverse Reactions Reported for ≥5% of Patients and More Frequently than Placebo in Any Treatment Group

N=59 %
ONFI Dose Level All ONFI
N=179 %
N=58 %
N=62 %
N=59 %
Gastrointestinal Disorders
Vomiting 5 9 5 7 7
Constipation 0 2 2 10 5
Dysphagia 0 0 0 5 2
General Disorders and Administration Site Conditions
Pyrexia 3 17 10 12 13
Irritability 5 3 11 5 7
Fatigue 2 5 5 3 5
Infections and Infestations
Upper respiratory tract infection 10 10 13 14 12
Pneumonia 2 3 3 7 4
Urinary tract infection 0 2 5 5 4
Bronchitis 0 2 0 5 2
Metabolism and Nutrition Disorders
Decreased appetite 3 3 0 7 3
Increased appetite 0 2 3 5 3
Nervous System Disorders
Somnolence or Sedation 15 17 27 32 26
Somnolence 12 16 24 25 22
Sedation 3 2 3 9 5
Lethargy 5 10 5 15 10
Drooling 3 0 13 14 9
Ataxia 3 3 2 10 5
Psychomotor hyperactivity 3 3 3 5 4
Dysarthria 0 2 2 5 3
Psychiatric Disorders
Aggression 5 3 8 14 8
Insomnia 2 2 5 7 5
Respiratory Disorders
Cough 0 3 5 7 5
aMaximum daily dose of 5 mg for ≤30 kg body weight; 10 mg for >30 kg body weight
bMaximum daily dose of 10 mg for ≤30 kg body weight; 20 mg for >30 kg body weight
cMaximum daily dose of 20 mg for ≤30 kg body weight; 40 mg for >30 kg body weight

Postmarketing Experience

These reactions are reported voluntarily from a population of uncertain size; therefore, it is not possible to estimate their frequency or establish a causal relationship to drug exposure. Adverse reactions are categorized by system organ class.

Blood Disorders: Anemia, eosinophilia, leukopenia, thrombocytopenia

Eye Disorders: Diplopia, vision blurred

Gastrointestinal Disorders: Abdominal distention

General Disorders and Administration Site Conditions: Hypothermia

Investigations: Hepatic enzyme increased

Musculoskeletal: Muscle spasms

Psychiatric Disorders: Agitation, anxiety, apathy, confusional state, depression, delirium, delusion, hallucination

Renal and Urinary Disorders: Urinary retention

Respiratory Disorders: Aspiration, respiratory depression

Skin and Subcutaneous Tissue Disorders: Rash, urticaria, angioedema, and facial and lip edema

Read the entire FDA prescribing information for Onfi (Clobazam Tablets and Oral Suspension)


If you have had a seizure, it means you have epilepsy. See Answer

© Onfi Patient Information is supplied by Cerner Multum, Inc. and Onfi Consumer information is supplied by First Databank, Inc., used under license and subject to their respective copyrights.

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