Medical Editor: John P. Cunha, DO, FACOEP Last updated on RxList: 5/10/2022
Sympazan Side Effects Center

What Is Sympazan?

Sympazan (clobazam) is a benzodiazepine indicated for adjunctive treatment of seizures associated with Lennox-Gastaut Syndrome (LGS) in patients 2 years of age or older.

What Are Side Effects of Sympazan?

Common side effects of Sympazan include:

Dosage for Sympazan

The initial dose of Sympazan for patients weighing 30 kg or less is 5 mg daily, and adjusted as tolerated up to 20 mg daily. The initial dose of Sympazan for patients weighing greater than 30 kg is 10 mg daily, and adjusted as tolerated up to 40 mg daily.

What Drugs, Substances, or Supplements Interact with Sympazan?

Sympazan may interact with alcohol, opioids, hormonal contraceptives, fluconazole, fluvoxamine, ticlopidine, or omeprazole. Tell your doctor all medications and supplements you use.

Sympazan During Pregnancy and Breastfeeding

Tell your doctor if you are pregnant or plan to become pregnant before using Sympazan; it may harm a fetus. There is a pregnancy exposure registry that monitors pregnancy outcomes in women exposed to AEDs, such as Sympazan, during pregnancy. Sympazan passes into breast milk and may cause adverse effects in nursing infants. Consult your doctor before breastfeeding. Withdrawal symptoms such as convulsions, psychosis, hallucinations, behavioral disorder, tremor, and anxiety may occur if you suddenly stop taking Sympazan.

Additional Information

Our Sympazan (clobazam) Oral Film, CIV 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.


What Is Epilepsy? Symptoms, Causes, and Treatments See Slideshow
Sympazan Consumer Information

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 Sympazan (Clobazam Oral Film)


See Images
Sympazan 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. The following adverse events have been reported in clinical trials of patients treated with clobazam, the active ingredient of SYMPAZAN®.

During its development for the adjunctive treatment of seizures associated with LGS, clobazam 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 clobazam at several doses to placebo.

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

The adverse reactions associated with clobazam 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 clobazam-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

Placebo N=59 % Clobazam Dose Level All Clobazam N=179 %
Lowa N=58 % Mediumb N=62 % Highc 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
a Maximum daily dose of 5 mg for ≤30 kg body weight; 10 mg for >30 kg body weight
b Maximum daily dose of 10 mg for ≤30 kg body weight; 20 mg for >30 kg body weight
c Maximum daily dose of 20 mg for ≤30 kg body weight; 40 mg for >30 kg body weight

Postmarketing Experience

The following adverse reactions have been identified during post-approval use of clobazam tablets. 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 GABAA 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 SYMPAZAN® with other CNS depressants may increase the risk of sedation and somnolence [see WARNINGS AND PRECAUTIONS].

Alcohol, as a CNS depressant, will interact with SYMPAZAN® 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 SYMPAZAN® On Other Drugs

Hormonal Contraceptives

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

Drugs Metabolized By CYP2D6

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

Effect Of Other Drugs On SYMPAZAN®

Strong And Moderate Inhibitors Of CYP2C19

Coadministration with strong or moderate inhibitors of CYP2C19 may result in increased exposure to Ndesmethylclobazam, the active metabolite of clobazam. This may increase the risk of dose-related adverse reactions. Dosage adjustment of SYMPAZAN® may be necessary when co-administered with strong CYP2C19 inhibitors (e.g., fluconazole, fluvoxamine, ticlopidine) or moderate CYP2C19 inhibitors (e.g., omeprazole) [see CLINICAL PHARMACOLOGY].

Effect Of Cannabidiol On SYMPAZAN®

Coadministration of cannabidiol, a CYP3A4 and CYP2C19 substrate and a CYP2C19 inhibitor, with clobazam may increase the risk of clobazam-related adverse reactions [see WARNINGS AND PRECAUTIONS, CLINICAL PHARMACOLOGY]. Consider a reduction in dosage of cannabidiol or clobazam if adverse reactions known to occur with SYMPAZAN are experienced.

Drug Abuse And Dependence

Controlled Substance

SYMPAZAN® contains clobazam, a Schedule IV controlled substance.


SYMPAZAN is a benzodiazepine and a CNS depressant with a potential for abuse and addiction. Abuse is the intentional, non-therapeutic use of a drug, even once, for its desirable psychological or physiological effects. Misuse is the intentional use, for therapeutic purposes, of a drug by an individual in a way other than prescribed by a health care provider or for whom it was not prescribed. Drug addiction is a cluster of behavioral, cognitive, and physiological phenomena that may include a strong desire to take the drug, difficulties in controlling drug use (e.g., continuing drug use despite harmful consequences, giving a higher priority to drug use than other activities and obligations), and possible tolerance or physical dependence. Even taking benzodiazepines as prescribed may put patients at risk for abuse and misuse of their medication. Abuse and misuse of benzodiazepines may lead to addiction.

Abuse and misuse of benzodiazepines often (but not always) involve the use of doses greater than the maximum recommended dosage and commonly involve concomitant use of other medications, alcohol, and/or illicit substances, which is associated with an increased frequency of serious adverse outcomes, including respiratory depression, overdose, or death. Benzodiazepines are often sought by individuals who abuse drugs and other substances, and by individuals with addictive disorders [see WARNINGS AND PRECAUTIONS].

The following adverse reactions have occurred with benzodiazepine abuse and/or misuse: abdominal pain, amnesia, anorexia, anxiety, aggression, ataxia, blurred vision, confusion, depression, disinhibition, disorientation, dizziness, euphoria, impaired concentration and memory, indigestion, irritability, muscle pain, slurred speech, tremors, and vertigo.

The following severe adverse reactions have occurred with benzodiazepine abuse and/or misuse: delirium, paranoia, suicidal ideation and behavior, seizures, coma, breathing difficulty, and death. Death is more often associated with polysubstance use (especially benzodiazepines with other CNS depressants such as opioids and alcohol).The World Health Organization epidemiology database contains reports of drug abuse, misuse, and overdoses associated with clobazam.


Physical Dependence

SYMPAZAN may produce physical dependence from continued therapy. Physical dependence is a state that develops as a result of physiological adaptation in response to repeated drug use, manifested by withdrawal signs and symptoms after abrupt discontinuation or a significant dose reduction of a drug. Abrupt discontinuation or rapid dosage reduction of benzodiazepines or administration of flumazenil, a benzodiazepine antagonist, may precipitate acute withdrawal reactions, including seizures, which can be life-threatening. Patients at an increased risk of withdrawal adverse reactions after benzodiazepine discontinuation or rapid dosage reduction include those who take higher dosages (i.e., higher and/or more frequent doses) and those who have had longer durations of use [see WARNINGS AND PRECAUTIONS].

To reduce the risk of withdrawal reactions, use a gradual taper to discontinue SYMPAZAN or reduce the dosage [see DOSAGE AND ADMINISTRATION and WARNINGS AND PRECAUTIONS].

Acute Withdrawal Signs and Symptoms

Acute withdrawal signs and symptoms associated with benzodiazepines have included abnormal involuntary movements, anxiety, blurred vision, depersonalization, depression, derealization, dizziness, fatigue, gastrointestinal adverse reactions (e.g., nausea, vomiting, diarrhea, weight loss, decreased appetite), headache, hyperacusis, hypertension, irritability, insomnia, memory impairment, muscle pain and stiffness, panic attacks, photophobia, restlessness, tachycardia, and tremor. More severe acute withdrawal signs and symptoms, including life-threatening reactions, have included catatonia, convulsions, delirium tremens, depression, hallucinations, mania, psychosis, seizures, and suicidality.

Protracted Withdrawal Syndrome

Protracted withdrawal syndrome associated with benzodiazepines is characterized by anxiety, cognitive impairment, depression, insomnia, formication, motor symptoms (e.g., weakness, tremor, muscle twitches), paresthesia, and tinnitus that persists beyond 4 to 6 weeks after initial benzodiazepine withdrawal. Protracted withdrawal symptoms may last weeks to more than 12 months. As a result, there may be difficulty in differentiating withdrawal symptoms from potential re-emergence or continuation of symptoms for which the benzodiazepine was being used.


Tolerance to SYMPAZAN may develop from continued therapy. Tolerance is a physiological state characterized by a reduced response to a drug after repeated administration (i.e., a higher dose of a drug is required to produce the same effect that was once obtained at a lower dose). Tolerance to the therapeutic effect of SYMPAZAN may develop; however, little tolerance develops to the amnestic reactions and other cognitive impairments caused by benzodiazepines.

Read the entire FDA prescribing information for Sympazan (Clobazam Oral Film)


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

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

Health Solutions From Our Sponsors