[9][1] Common side effects may include sleepiness, weakness, poor coordination, difficulty concentrating, and agitation.

[11] Clonazepam binds to GABAA receptors, thus increasing the effect of the chief inhibitory neurotransmitter γ-aminobutyric acid (GABA).

[28] A subgroup of people with treatment-resistant epilepsy may benefit from long-term use of clonazepam; the benzodiazepine clorazepate may be an alternative due to its slow onset of tolerance.

Patients dependent on clonazepam should be slowly titrated off under the supervision of a qualified healthcare professional to reduce the intensity of withdrawal or rebound symptoms.

Benzodiazepines such as clonazepam can be very effective in controlling status epilepticus, but, when used for longer periods of time, some potentially serious side-effects may develop, such as interference with cognitive functions and behavior.

[79][80] One-third of individuals treated with benzodiazepines for longer than four weeks develop a dependence on the drug and experience a withdrawal syndrome upon dose reduction.

Due to the risks of tolerance and withdrawal seizures, clonazepam is generally not recommended for the long-term management of epilepsies.

[89] The combination of clonazepam and certain barbiturates (for example, amobarbital), at prescribed doses has resulted in a synergistic potentiation of the effects of each drug, leading to serious respiratory depression.

[91] Clonazepam and 7-aminoclonazepam may be quantified in plasma, serum, or whole blood in order to monitor compliance in those receiving the drug therapeutically.

Results from such tests can be used to confirm the diagnosis in potential poisoning victims or to assist in the forensic investigation in a case of fatal overdosage.

Both the parent drug and 7-aminoclonazepam are unstable in biofluids, and therefore specimens should be preserved with sodium fluoride, stored at the lowest possible temperature and analyzed quickly to minimize losses.

[10] The elderly are especially susceptible to increased risk of harm from motor impairments and drug accumulation side effects.

Benzodiazepines also require special precaution if used by individuals that may be pregnant, alcohol- or drug-dependent, or may have comorbid psychiatric disorders.

[93] Clonazepam is generally not recommended for use in elderly people for insomnia due to its high potency relative to other benzodiazepines.

A 1982 double-blinded, placebo-controlled study found clonazepam increases violent behavior in individuals with chronic schizophrenia.

The data are also inconclusive on whether benzodiazepines such as clonazepam cause developmental deficits or decreases in IQ in the developing fetus when taken by the mother during pregnancy.

Withdrawal symptoms from benzodiazepines in the neonate may include hypotonia, apnoeic spells, cyanosis, and impaired metabolic responses to cold stress.

Possible adverse effects of use of benzodiazepines such as clonazepam during pregnancy include: miscarriage, malformation, intrauterine growth retardation, functional deficits, carcinogenesis, and mutagenesis.

Neonatal withdrawal syndrome associated with benzodiazepines include hypertonia, hyperreflexia, restlessness, irritability, abnormal sleep patterns, inconsolable crying, tremors, or jerking of the extremities, bradycardia, cyanosis, suckling difficulties, apnea, risk of aspiration of feeds, diarrhea and vomiting, and growth retardation.

In many cases, non-pharmacological treatments, such as relaxation therapy, psychotherapy, and avoidance of caffeine, can be an effective and safer alternative to the use of benzodiazepines for anxiety in pregnant women.

[109] Clonazepam enhances the activity of the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) in the central nervous system to give its anticonvulsant, skeletal muscle relaxant, and anxiolytic effects.

[10] In addition, clonazepam decreases the utilization of 5-HT (serotonin) by neurons[115][116] and has been shown to bind tightly to central-type benzodiazepine receptors.

[120] The anticonvulsant properties of benzodiazepines are due to the enhancement of synaptic GABA responses, and the inhibition of sustained, high-frequency repetitive firing.

Erythromycin, clarithromycin, ritonavir, itraconazole, ketoconazole, nefazodone, cimetidine, and grapefruit juice are inhibitors of CYP3A4 and can affect the metabolism of benzodiazepines.

[10] Peak blood concentrations of 6.5–13.5 ng/mL were usually reached within 1–2 hours following a single 2 mg oral dose of micronized clonazepam in healthy adults.

The criteria for non-medical use in this study were purposefully broad, and include, for example, drug abuse, accidental or intentional overdose, or adverse reactions resulting from legitimate use of the medication.

[140] It is marketed under the brand name Rivotril by Roche in Argentina, Australia, Austria, Bangladesh, Belgium, Brazil, Canada, Colombia, Costa Rica, Croatia, the Czech Republic, Denmark, Estonia,[141] Germany, Hungary, Iceland, Ireland, Italy, China, Mexico, the Netherlands, Norway, Portugal, Peru, Pakistan, Romania, Serbia, South Africa, South Korea, Spain, Turkey, and the United States; Emcloz, Linotril, Lonazep, Clotrin and Clonotril in India and other parts of Europe; under the name Riklona in Indonesia and Malaysia; and under the brand name Klonopin by Roche in the United States.

Other names, such as Antelepsin, Clonoten, Ravotril, Rivotril, Iktorivil, Clonex (Israel), Paxam, Petril, Naze, Zilepam and Kriadex, are used throughout the world.