Azole antifungals, such as ketoconazole, may inhibit the metabolism of clonazepam. Clonazepam may affect levels of phenytoin (diphenylhydantoin). In turn, Phenytoin may lower clonazepam plasma levels by increasing the speed of clonazepam clearance by approximately 50% and decreasing its half-life by 31%. Clonazepam increases the levels of primidone and phenobarbital.Combined use of clonazepam with certain antidepressants, anticonvulsants (such as phenobarbital, phenytoin, and carbamazepine), sedative antihistamines, opiates, and antipsychotics, nonbenzodiazepines (such as zolpidem), and alcohol may result in enhanced sedative effects. Pregnancy
There is some medical evidence of various malformations (for example, cardiac or facial deformations when used in early pregnancy); however, the data is not conclusive. 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. Clonazepam, when used late in pregnancy, may result in the development of a severe benzodiazepine withdrawal syndrome in the neonate. Withdrawal symptoms from benzodiazepines in the neonate may include hypotonia, apnoeic spells, cyanosis, and impaired metabolic responses to cold stress.The safety profile of clonazepam during pregnancy is less clear than that of other benzodiazepines, and if benzodiazepines are indicated during pregnancy, chlordiazepoxide and diazepam may be a safer choice. The use of clonazepam during pregnancy should only occur if the clinical benefits are believed to outweigh the clinical risks to the fetus. Caution is also required if clonazepam is used during breastfeeding.
Rapid eye movement sleep behavior disorder responds well to low doses of clonazepam. The treatment of acute and chronic akathisia induced by neuroleptics, also called antipsychotics. Spasticity related to amyotrophic lateral sclerosis. Alcohol withdrawal syndrome

Other
Benzodiazepines, such as clonazepam, are sometimes used for the treatment of mania or acute psychosis-induced aggression. In this context, benzodiazepines are given either alone, or in combination with other first-line drugs such as lithium, haloperidol or risperidone. The effectiveness of taking benzodiazepines along with antipsychotic medication is unknown, and more research is needed to determine if benzodiazepines are more effective than antipsychotics when urgent sedation is required. Hyperekplexia
Many forms of parasomnia and other sleep disorders are treated with clonazepam. It is not effective for preventing migraines. Contraindications
Coma
Current alcohol use disorder
Current substance use disorder
Respiratory depression. Adverse effects
In September 2020, the U.S. Food and Drug Administration (FDA) required the boxed warning be updated for all benzodiazepine medicines to describe the risks of abuse, misuse, addiction, physical dependence, and withdrawal reactions consistently across all the medicines in the class. Common
Sedation
Euphoria
Motor impairment

Less common
Confusion
Irritability and aggression
Psychomotor agitation
Lack of motivation
Loss of libido
Impaired motor functionImpaired coordination
Impaired balance
Dizziness
Cognitive impairmentsHallucinations. Short-term memory loss
Anterograde amnesia (common with higher doses)
Some users report hangover-like symptoms of drowsiness, headaches, sluggishness, and irritability upon waking up if the medication was taken before sleep. This is likely the result of the medications long half-life, which continues to affect the user after waking up. While benzodiazepines induce sleep, they tend to reduce the quality of sleep by suppressing or disrupting REM sleep.