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Onfi Side Effects

Generic Name: clobazam

Note: This document contains side effect information about clobazam. Some of the dosage forms listed on this page may not apply to the brand name Onfi.

In Summary

Common side effects of Onfi include: constipation, drowsiness, fever, sedation, aggressive behavior, ataxia, lethargy, drooling, and irritability. Other side effects include: pneumonia, urinary tract infection, cough, bronchitis, dysarthria, dysphagia, fatigue, insomnia, decreased appetite, and increased appetite. See below for a comprehensive list of adverse effects.

For the Consumer

Applies to clobazam: oral suspension, oral tablet

Along with its needed effects, clobazam (the active ingredient contained in Onfi) may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking clobazam:

More common
  • Difficulty with swallowing
  • fever
  • shakiness and unsteady walk
  • unsteadiness, trembling, or other problems with muscle control or coordination
Less common
  • Change in speech pattern
  • restlessness
  • slurred speech
  • trouble sitting still
  • trouble speaking
Incidence not known
  • Agitation
  • black, tarry stools
  • bleeding gums
  • blistering, peeling, or loosening of the skin
  • blood in the urine or stools
  • chest pain
  • chills
  • confusion as to time, place, or person
  • cough
  • diarrhea
  • difficult or troubled breathing
  • holding false beliefs that cannot be changed by fact
  • irregular, fast or slow, or shallow breathing
  • itching
  • joint or muscle pain
  • lack of feeling or emotion
  • painful or difficult urination
  • pale or blue lips, fingernails, or skin
  • pinpoint red spots on the skin
  • red skin lesions, often with a purple center
  • red, irritated eyes
  • seeing, hearing, or feeling things that are not there
  • sore throat
  • sores, ulcers, or white spots in the mouth or on the lips
  • swollen glands
  • troubled breathing with exertion
  • unusual bleeding or bruising
  • unusual excitement, nervousness, or restlessness
  • unusual tiredness or weakness

Some side effects of clobazam may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common
  • Aggressive
  • body aches or pain
  • decreased appetite
  • difficulty having a bowel movement (stool)
  • drooling
  • ear congestion
  • irritability
  • loss of voice
  • nasal congestion
  • runny nose
  • sleepiness or unusual drowsiness
  • sneezing
  • vomiting
Less common
  • Bladder pain
  • cloudy urine
  • cough with mucus
  • frequent urge to urinate
  • increased appetite
  • lower back or side pain
Incidence not known
  • Double vision
  • full or bloated feeling
  • headache
  • muscle spasms
  • pressure in the stomach
  • rash, hives, or welts
  • red skin
  • swelling of the stomach area

For Healthcare Professionals

Applies to clobazam: oral suspension, oral tablet


The most commonly reported side effects were somnolence or sedation, tiredness, pyrexia, and lethargy.[Ref]

Nervous system

Very common (10% or more): Somnolence or sedation (up to 32%), drowsiness (up to 32%), somnolence (up to 25%), lethargy (up to 15%), drooling (up to 14%), ataxia (up to 10%)
Common (1% to 10%): Dizziness, dysarthria, headache, psychomotor hyperactivity, sedation, slurred speech, tremor
Frequency not reported: Amnesia, anterograde amnesia, disorders of articulation, disturbance in attention, fine finger tremor, hangover, impairment in consciousness, memory impairment, nystagmus, potentiation of sedation from concomitant use with central nervous system depressants, sleepiness, slowed/indistinct speech, slowing of reaction time, speech disorder, unsteadiness of gait and other motor functions, unsteady movement[Ref]


Very common (10% or more): Tiredness (up to 32%), pyrexia (up to 17%)
Common (1% to 10%): Fatigue
Frequency not reported: Drug tolerance, fall, hypothermia, risks from concomitant use with opioids, paradoxical reactions[Ref]


Very common (10% or more): Aggression/aggressiveness (up to 14%), irritability (up to 11%)
Common (1% to 10%): Confusion, depression, insomnia
Frequency not reported: Acute agitational states, agitation, anxiety, benzodiazepine abuse, decreased libido, delusion, difficulty falling asleep/sleeping through, euphoria, fits of rage, habituation, hallucinations, inappropriate behavior, loss of libido, nightmares, numbed emotions, physical and psychological dependence, psychotic reactions, restlessness, suicidal behavior and ideations, suicidal tendencies, unmasking of preexisting depression, withdrawal symptoms/rebound phenomena
Postmarketing reports: Apathy, confusional state, delirium[Ref]


Very common (10% or more): Upper respiratory tract infection (up to 14%)
Common (1% to 10%): Bronchitis, cough, pneumonia
Frequency not reported: Deterioration of respiratory insufficiency, respiratory depression, respiratory disorders, respiratory insufficiency
Postmarketing reports: Aspiration[Ref]


Very common (10% or more): Constipation (up to 10%)
Common (1% to 10%): Diarrhea, dry mouth, dysphagia, nausea, vomiting
Postmarketing reports: Abdominal distention[Ref]


Common (1% to 10%): Decreased appetite, increased appetite
Frequency not reported: Anorexia, appetite loss, weight gain[Ref]


Common (1% to 10%): Rash
Frequency not reported: Cutaneous reaction, photosensitivity reactions, pruritus, serious dermatological reactions, Stevens-Johnson syndrome (SJS)/fatal SJS, sweating, toxic epidermal necrolysis (TEN)/fatal TEN, urticaria
Postmarketing reports: Facial and lip edema[Ref]


Common (1% to 10%): Urinary tract infection
Postmarketing reports: Urinary retention[Ref]


Common (1% to 10%): Hypotension[Ref]


Frequency not reported: Muscle aches, muscle spasm/frequent muscle spasms, muscle stiffness, muscle weakness[Ref]


Frequency not reported: Blurred vision, diplopia/double vision, visual disorders[Ref]


Frequency not reported: Abnormal hematologic laboratory tests
Postmarketing reports: Anemia, eosinophilia, leukopenia, thrombocytopenia[Ref]


Frequency not reported: Abnormal liver function tests
Postmarketing reports: Increased hepatic enzymes[Ref]


Postmarketing reports: Angioedema[Ref]


1. "Product Information. Frisium (clobazam)." Sanofi-Aventis, Laval, IN.

2. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0

3. Cerner Multum, Inc. "Australian Product Information." O 0

4. "Product Information. Onfi (clobazam)." Lundbeck Inc, Deerfield, IL.

Some side effects of Onfi may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This material does not endorse drugs, diagnose patients, or recommend therapy. This information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate safety, effectiveness, or appropriateness for any given patient. does not assume any responsibility for any aspect of healthcare administered with the aid of materials provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the substances you are taking, check with your doctor, nurse, or pharmacist.