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Side Effects of Clobazam (Onfi)


Clobazam (Onfi) Side Effects

Clobazam, available under the common brand Onfi, is an anticonvulsant prescription medicine part of the benzodiazepine drug class. Onfi is combined with other medicines to treat seizures associated with Lennox-Gastaut syndrome (type of epilepsy with different types of seizures).

Addiction to Onfi

According to the FDA, Onfi is a federally controlled substance (C-IV) because it has abuse or dependence potential. Keep Onfi in a safe place. It is illegal to sell or give away this medicine. Inform your healthcare provider about alcohol abuse or dependence history, and usage of prescription medicines or street drugs.

Serious Side Effects

The FDA reports Onfi usage may result in severe adverse drug reactions. Onfi can cause suicidal thoughts or actions in about 1 in 500 people. Immediately contact your healthcare provider if you have any of these symptoms:


  • Suicide ideation or attempts
  • Depression
  • Anxiety
  • Panic attacks
  • New or worse irritability
  • Insomnia or trouble sleeping
  • Being angry or violent
  • Acting aggressive or on dangerous impulses
  • Extreme increase in activity and talking (mania)
  • Feeling agitated or restless
  • Other unusual changes in behavior or mood


Onfi can cause withdrawal symptoms, such as continuous seizures (status epilepticus), hearing or seeing things that are not there (hallucinations), shaking, nervousness, and stomach and muscle cramps if stopped. Consult your healthcare provider about slowly stopping Onfi treatment to avoid withdrawal symptoms.


Severe skin reactions can occur during your treatment with Onfi within the initial 8 weeks. Contact your healthcare provider immediately if you have skin blisters, peeling rash, sores in the mouth, hives or any other allergic skin reactions.

Common Side Effects

The most common side effects of Onfi include:


  • Sleepiness and tiredness
  • Drooling
  • Constipation
  • Cough
  • Pain during urination
  • Fever
  • Aggressive, angry, or violent behavior
  • Difficulty sleeping
  • Slurred speech
  • Breathing complications
  • Dizziness
  • Slow thinking processes
  • Clumsiness


(Onfi label reported by the FDA).

About Pharmacogenetic Testing

CYP2C19 has an impact on the efficacy and side effects of Onfi because it is primarily responsible for its metabolism in the body. Individuals with low CYP2C19 activity, known as “poor metabolizers” are at high risk of experiencing side effects and lower dose are recommended compared to normal individuals (Pharmacotherapy “Pharmacogenetic Testing for Neuropsychiatric Drugs” February 2014). CYP2C19 testing can be valuable tools to offer individualized Onfi therapy.


The trial-and-error process of medication treatments has caused a great deal of problems in the United States. It has led to medication addiction, ineffective treatment and hospitalizations. Genetic testing aims to stop this problem by testing the patients DNA and seeing how the medicine interacts with those genes. Once this is understood, the patient can make an informed decision and decide whether the drug is right for him.

Know Your Risk for Side Effects with the Rxight® Genetic Test

The Rxight® test’s primary function is to provide accurate, reliable, and easy to understand genetic information for you and your pharmacist. With these results, your pharmacist will have a better understanding of how over 200 prescription and over-the-counter (OTC) medications affect you. The Rxight results are designed to guide your pharmacist in creating the safest and best plan for you.


For more information on Rxight® pharmacogenetic testing, call us at 1-888-888-1932 or email us at support@Rxight.com.


Contributors to this Article:
Michael Sapko, MD, PhD; and Deborah Kallick, PhD, Medicinal Chemistry

Read more about Rxight® Genetic Testing Labs