Onfi Side Effects Center

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).

Clobazam can slow or stop your breathing, especially if you have recently used an opioid medication or alcohol. A person caring for you should seek emergency medical attention if you have slow breathing with long pauses, blue colored lips, or if you are hard to wake up.

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.

Call your doctor at once if you have:

  • weak or shallow breathing;
  • severe drowsiness, feeling like you might pass out; or
  • problems with balance or muscle movement.

Drowsiness or dizziness may last longer in older adults. Use caution to avoid falling or accidental injury.

Common side effects may include:

  • drowsiness, tiredness, trouble sleeping;
  • slurred speech;
  • anger, aggression;
  • constipation;
  • painful urination;
  • fever, cough, breathing problems; 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)


If you have had a seizure, it means you have epilepsy. See Answer
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]
  • Abuse, Misuse, and Addiction [see WARNINGS AND PRECAUTIONS]
  • Dependence and Withdrawal Reactions [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]
  • Serious Dermatological Reactions [see CONTRAINDICATIONS, 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

ONFI Dose Level All ONFI
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
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



The concomitant use of benzodiazepines and opioids increases the risk of respiratory depression because of actions at different receptor sites in the CNS that control respiration. Benzodiazepines interact at GABA sites, and opioids interact primarily at mu receptors. When benzodiazepines and opioids are combined, the potential for benzodiazepines to significantly worsen opioid-related respiratory depression exists. Limit dosage and duration of concomitant use of benzodiazepines and opioids, and follow patients closely for respiratory depression and sedation [see WARNINGS AND PRECAUTIONS].

CNS Depressants And Alcohol

Concomitant use of ONFI with other CNS depressants may increase the risk of sedation and somnolence [see WARNINGS AND PRECAUTIONS].

Alcohol, as a CNS depressant, will interact with ONFI in a similar way and also increases clobazam's maximum plasma exposure by approximately 50%. Therefore, caution patients or their caregivers against simultaneous use with other CNS depressant drugs or alcohol, and caution that the effects of other CNS depressant drugs or alcohol may be potentiated [see WARNINGS AND PRECAUTIONS].

Effect Of ONFI On Other Drugs

Hormonal Contraceptives

ONFI is a weak CYP3A4 inducer. As some hormonal contraceptives are metabolized by CYP3A4, their effectiveness may be diminished when given with ONFI. Additional non-hormonal forms of contraception are recommended when using ONFI [see CLINICAL PHARMACOLOGY, Patient Counseling Information].

Drugs Metabolized By CYP2D6

ONFI inhibits CYP2D6. Dose adjustment of drugs metabolized by CYP2D6 may be necessary [see CLINICAL PHARMACOLOGY].

Effect Of Other Drugs On ONFI

Strong And Moderate Inhibitors Of CYP2C19

Strong and moderate inhibitors of CYP2C19 may result in increased exposure to N-desmethylclobazam, the active metabolite of clobazam. This may increase the risk of dose-related adverse reactions. Dosage adjustment of ONFI may be necessary when coadministered with strong CYP2C19 inhibitors (e.g., fluconazole, fluvoxamine, ticlopidine) or moderate CYP2C19 inhibitors (e.g., omeprazole) [see CLINICAL PHARMACOLOGY].

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


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© 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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