Last reviewed 2026-04-20 · How we verify

Klonopin (clonazepam)

Clonazepam (Klonopin), a long-acting, high-potency benzodiazepine, is a generic drug originally developed by Roche and currently marketed for Lennox-Gastaut Syndrome. Its key strength lies in its extended half-life of 30-40 hours, which supports its efficacy in managing seizure disorders and panic disorder. The primary risk is the key composition patent expiry in 2028, which may increase competition from other generics.

At a glance

Approved indications

• Lennox-Gastaut Syndrome
• Akinetic Seizures
• Myoclonic Seizures
• Absence Seizures
• Panic Disorder

Boxed warnings

• WARNING: RISKS FROM CONCOMITANT USE WITH OPIOIDS; ABUSE, MISUSE, AND ADDICTION; and DEPENDENCE AND WITHDRAWAL REACTIONS Concomitant use of benzodiazepines and opioids may result in profound sedation, respiratory depression, coma, and death. Reserve concomitant prescribing of these drugs for patients for whom alternative treatment options are inadequate. Limit dosages and durations to the minimum required. Follow patients for signs and symptoms of respiratory depression and sedation (see WARNINGS and PRECAUTIONS ). The use of benzodiazepines, including clonazepam tablets, exposes users to risks of abuse, misuse, and addiction, which can lead to overdose or death. Abuse and misuse of benzodiazepines commonly involve concomitant use of other medications, alcohol, and/or illicit substances, which is associated with an increased frequency of serious adverse outcomes. Before prescribing clonazepam tablets and throughout treatment, assess each patient’s risk for abuse, misuse, and addiction (see WARNINGS ). The continued use of benzodiazepines, including clonazepam tablets, may lead to clinically significant physical dependence. The risks of dependence and withdrawal increase with longer treatment duration and higher daily dose. Abrupt discontinuation or rapid dosage reduction of clonazepam tablets after continued use may precipitate acute withdrawal reactions, which can be life-threatening. To reduce the risk of withdrawal reactions, use a gradual taper to discontinue clonazepam tablets or reduce the dosage (see DOSAGE AND ADMINISTRATION and WARNINGS ).

Common side effects

• Drowsiness
• Ataxia
• Behavior Problems
• Somnolence
• Depression
• Nausea
• Dizziness
• Nervousness
• Intellectual Ability Reduced
• Muscle Weakness
• Headache
• Confusion

Serious adverse events

• Respiratory Depression
• Coma
• Psychosis
• Hallucinations
• Hepatomegaly
• Transient Elevations of Serum Transaminases
• Anemia
• Leukopenia
• Thrombocytopenia
• General Deterioration

Key clinical trials

• Treatment Refractory Panic Disorder (Phase 2)
• The Effectiveness and Efficacy of the Combination of Pharmacotherapy With the Two New Recovery-oriented Programs, RECOVERYTRSGR (Treatment Resistant Schizophrenia) and RECOVERYTRSBDGR (Treatment Resis (Phase 4)
• An International Phase II Trial Assessing Tolerability and Efficacy of Sequential Methotrexate-Aracytin-based Combination and R-ICE Combination, Followed by HD Chemotherapy Supported by ASCT, in Patie (Phase 2)
• Pharmacovigilance in Gerontopsychiatric Patients (Phase 3)
• Efficacy of Clonidine in Reducing Craving in Inpatients With Cocaine and Crack Use Disorder: a Randomized Clinical Trial. (Phase 4)
• Efficacy of Intravenous Clonazepam According to the Dosage in Children Status Epilepticus (N/A)
• A Randomized Double-Blind, Double-Dummy, Crossover Study to Evaluate the Efficacy and Safety of Prolonged-Release Melatonin and Clonazepam in Patients With Rapid Eye Movement (REM) Sleep Behavior Diso (Phase 2)
• Additional Value of Deanxit in Tinnitus Patients Treated With Rivotril (Phase 4)

Primary sources

Every claim on this page is sourced from regulatory or scientific primary sources. See our editorial policy for full methodology.