Written by: THE BALANCE
Medically reviewed by Dr. Sarah Boss, MD
Last updated: January 19, 2026
Fact checked
Quick Summary
  • Clonazepam, like all other benzodiazepines, possesses a myriad of side effects that present with its use.
  • Side effects of Clonazepam are sometimes even present when taken in prescribed doses.
  • Dizziness: Individuals using Clonazepam usually feel dizzy and fatigued even after a night of rested sleep.  Retrograde Amnesia: This is a condition in which an individual has a hampered memory and finds it difficult to retain new information.

Clonazepam, like all other benzodiazepines, possesses a myriad of side effects that present with its use. Side effects of Clonazepam are sometimes even present when taken in prescribed doses. Some of the common side effects of Clonazepam are as follows:

  • Drowsiness: As Clonazepam acts by reducing the activity of the Central Nervous System, mediated by the release of GABA which produces a tranquilizing effect so drowsiness is frequently encountered due to the sedative and relaxing effect of the drug. 
  • Movement problems: Since Clonazepam slows the brain’s functioning, it results in impaired coordination that results in falls and movement problems.
  • Dizziness: Individuals using Clonazepam usually feel dizzy and fatigued even after a night of rested sleep. 
  • Retrograde Amnesia: This is a condition in which an individual has a hampered memory and finds it difficult to retain new information. This is a side effect of Clonazepam as it reduces the neuronal excitement n the brain and acts as a central nervous system depressant reducing the brain’s ability to memorize and store information.
  • Sleep-related activities: Individuals taking Clonazepam often indulge in activities during their sleep such that they might be cooking, driving, making a phone call under the effect of the drug and they would have no recollection of these events which is quite frightening and risky for an individual’s safety and those around him or her.
  • Disorientation: Since the brain is not alert under the effect of Clonazepam, the individual feels disoriented.
  • Slurred speech: It is commonly seen in individuals who use a central nervous system depressant because there is slowing of motor skills such as speech which results in slurring of speech. 
  • Shallow breathing: As Clonazepam acts by depressing the central nervous system, the respiratory centers in the CNS also get depressed making breathing a labored task and this can further lead to various complications. 
  • Difficulty concentrating: When the brain is working at less than its optimum limit, because of a decrease in its activity caused by the action of Clonazepam, the individual finds it very hard to focus on things since the brain is not alert since Clonazepam has sedative properties.
  • Insomnia: This is a frequently encountered side effect of Clonazepam as the drug causes drowsiness and fatigue the next day of its use. 
  • Confusion: Mental confusion with impaired judgment and decision-making ability is an oft found side effect with Clonazepam use.
  • Hallucination: Tactile, visual, and auditory hallucinations are reported with Clonazepam use and it is assumed that it is due to the effect of Clonazepam on the brain that causes increased levels of serotonin which result in these hallucinations. 
  • Unusual heartbeat: Clonazepam affects the cardiovascular system and hence individual experiences an unusual heartbeat.

When individuals take Clonazepam for a longer period or in increased doses following side effects result: (source: MedlinePlus, n.d.)

  • Memory loss
  • Weakness
  • Dry mouth
  • Hoarseness
  • Paranoia  
  • Increased risk of falls, injuries, and car-crash accidents
  • Overdose
  • Tolerance
  • Physiological dependence
  • Addiction
  • Poly-substance Abuse
  • Aggression
  • Hostility
  • Anti-social behavior
  • Birth defects in unborn babies
  • Withdrawal symptoms

Since Clonazepam is a habit-forming drug it is often prescribed for a short duration of time so that dependence does not develop on the drug as this can happen even with prescribed doses. Initially, dependence and addiction begin as tolerance. When an individual is taking Clonazepam for a long period, he soon becomes tolerant to the drug dose such that he requires increased doses to achieve the original effect. Dependence soon develops after tolerance where an individual becomes dependent on the stimulus caused by the drug. 

Is Clonazepam an Addictive drug? (source: NHS, 2024)

Clonazepam stimulates the release of GABA neurotransmitters in the brain and eventually, the brain becomes dependent on this stimulus, and when the supply of Clonazepam is interrupted the brain is unable to maintain the balance of the neurotransmitter and unpleasant withdrawal symptoms ensue.  (source: NIDA, n.d.)

One of the most feared long-term side effects of Clonazepam is abuse and addiction to the drug which means that despite knowing and experiencing the negative effects of the drug, the individual feels a compulsion to continue taking the drug. This leads to a vicious cycle of abuse that can have fatal consequences, such as an overdose of Clonazepam, a medical emergency. 

Long-term use of Clonazepam in pregnant mothers is associated with birth defects in their baby hence Clonazepam should be avoided in pregnancy.  (source: NICE, 2022)

Benzodiazepines such as Clonazepam are known to cause low blood pressure. Clonazepam acts on the brain by increasing the levels of GABA, which slows down the heart rate and blood pressure. 

In research conducted on benzodiazepine consumption and ambulatory blood pressure monitoring, lower diastolic and systolic blood pressure was recorded in patients older than 60 years of age.  (source: StatPearls, 2025)

Individuals using Clonazepam (Klonopin) struggle with insomnia throughout the night, and they are left feeling tired and fatigued the next morning, unable to keep their eyes open during the day. This leads to daytime sleepiness and a state of constant drowsiness throughout the day.   (source: AAFP, 2019)

For some individuals who get a proper night of sleep after Clonazepam, sleepiness, and drowsiness are still present since the brain is fatigued after Clonazepam use. 

Certain physical side effects are associated with the long-term use of Clonazepam. They are as follows: (source: NCBI Bookshelf, 2021)

  • Body aches
  • An ear infection that can develop due to the collection of fluid in the ear
  • The immune system gets weakened
  • Urinary tract infection
  • Joint pain
  • Decreased sex drive
  • Brain atrophy
  • Tremors
  • Tightness and pain in the chest
  • Cerebral ventricular enlargement 

Clonazepam causes a list of psychological and behavioral alterations in individuals using this drug. These side effects are as follows:

  • Visual, tactile, and auditory hallucinations
  • Depression
  • Depersonalization 
  • Anxiousness
  • Irrational thoughts that they are being controlled by someone
  • Sense of worry that other people can read their mind
  • Vivid nightmares
  • Inability to suppress or control the negative thoughts or behavior
  • Lack of interest in activities that earlier used to cause them joy
  • Extreme mood swings
  • Excitement without any reason 
  • Unexplained anger and rage
  • Being emotionally numb
  • Coldness  towards others
  • Nervousness
  • Suicidal thoughts
  • Inability to experience pleasure 
  • Behave in a strange way that is not part of their character
  • Anxiousness

FAQs

What are the side effects of Clonazepam 0.5mg?
Clonazepam 0.5mg is used as an anticonvulsant or anti-epileptic to prevent and control seizures. It is associated with drowsiness, unsteadiness, dizziness, muscle and joint pain, and frequent urination. 

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