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Clobazam Side Effects

In Summary

Commonly reported side effects of clobazam 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

In addition to its needed effects, some unwanted effects may be caused by clobazam. In the event that any of these side effects do occur, they may require medical attention.

Major Side Effects

You should check with your doctor immediately if any of these side effects occur when 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

Minor Side Effects

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

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, lethargy, drooling, and ataxia.[Ref]


Very common (10% or more): Aggression (up to 14%)
Common (1% to 10%): Insomnia, irritability, depression
Uncommon (0.1% to 1%): Decreased libido or loss of libido, euphoria, numbed emotions, preexisting depression may be unmasked during benzodiazepine use
Frequency not reported: Withdrawal symptoms, physical and psychological dependence, suicidal behavior and ideation
Postmarketing reports: Agitation, anxiety, apathy, confusional state, delirium, delusion, hallucination[Ref]

Nervous system

Very common (10% or more): Somnolence ( up to 32%), lethargy (up to 15%), drooling ( up to 14%), ataxia (up to 10%)
Common (1% to 10%): Sedation, psychomotor hyperactivity, dysarthria, dizziness, headache, confusion, slurred speech, tremor
Uncommon (0.1% to 1%): Anterograde amnesia, amnesia
Frequency not reported: Potentiation of sedation from concomitant use with central nervous system depressants[Ref]


Common (1% to 10%): Rash
Uncommon (0.1% to 1%): Sweating
Postmarketing reports: Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), urticaria, angioedema, facial and lip edema[Ref]


Postmarketing reports: Increased hepatic enzyme[Ref]


Very common (10% or more): Upper respiratory tract infection (up to 14%)
Common (1% to 10%): Pneumonia, bronchitis, cough
Uncommon (0.1% to 1%): Respiratory depression
Postmarketing reports: Aspiration, respiratory depression[Ref]


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


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


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


Common (1% to 10%): Increased appetite, decreased appetite
Uncommon (0.1% to 1%): Anorexia[Ref]


Uncommon (0.1% to 1%): Muscle aches, weakness, stiffness, spasm[Ref]


Frequency not reported: Nystagmus
Postmarketing reports: Diplopia, vision blurred[Ref]


Very common (10% or more): Pyrexia ( up to 17%), irritability (up to 11%)
Common (1% to 10%): Fatigue
Uncommon (0.1% to 1%): Hangover
Postmarketing reports: Hypothermia[Ref]


Postmarketing reports: Anemia, eosinophilia, leukopenia, thrombocytopenia[Ref]


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

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

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

Not all side effects for clobazam may be reported. You should always consult a doctor or healthcare professional for medical advice. Side effects can be reported to the FDA here.

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