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Prescription pad with pill bottle: Clonazepam side effects
Drug Info

Clonazepam side effects and how to avoid them

Clonazepam (Klonopin) is a prescription drug that treats panic attacks, and certain types of seizures. Because it affects the central nervous system, clonazepam can have many side effects, including drug abuse and dependence.
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By | Oct. 5, 2021 Medically reviewed by Josephine Bawab, Pharm.D.

Clonazepam side effects | Serious side effects | Impairment |
Suicide | How long do side effects last? | Warnings | Interactions | How to avoid side effects Resources

Clonazepam is a prescription drug that is generic for Klonopin. It is prescribed to control panic attacks in adults diagnosed with panic disorder with or without agoraphobia (fear of being in a setting that is hard to escape) and treats certain types of seizures in adults and children. As a benzodiazepine, clonazepam is a GABA-A agonist that increases the effects of GABA, which calms brain activity. Because it affects the central nervous system, clonazepam can have many side effects, including serious ones like drug abuse and dependence. For this reason, people should always be well-informed about benzodiazepines like clonazepam before taking the first dose, including common side effects, serious side effects, drug interactions, contraindications, warnings, and ways to take these drugs safely. 

RELATED: What is clonazepam?

Common side effects of clonazepam

The most common side effects of clonazepam are:

Serious side effects of clonazepam

The most common serious side effects of clonazepam are: 

  • Suicidality
  • Physical dependency
  • Drug abuse
  • Withdrawal
  • Worsening of seizures
  • Respiratory depression (when taken with opioids)
  • Heart palpitations
  • Orthostatic hypotension (drop in blood pressure when standing)
  • Fainting
  • Reduction in red blood cells (anemia), white blood cells (leukopenia), and blood platelet count (thrombocytopenia) 
  • Paradoxical reactions such as irritability, excitability, anxiety, and nervousness

Clonazepam and impairment

Most people who take clonazepam will experience some kind of mental impairment, whether clonazepam is used as an anticonvulsant or an anxiety medication. About half of patients experience drowsiness when taking clonazepam, a third have problems with coordination, and a fourth will experience changes in their behavior. A small percentage will experience memory impairment or have difficulty thinking and concentrating. Impairment significantly raises the risk of falls, injuries, and accidents. People taking clonazepam should be cautious about driving, operating machinery, or engaging in anything that might cause injury. They should also be aware that they can be convicted of a DUI if any of the drug is detected in a blood test. People on clonazepam should also avoid taking anything else that will worsen mental impairment. This includes alcohol, over-the-counter antihistamines, or prescription depressants like opioids or sedatives.

Clonazepam and suicide

Like other anticonvulsants, clonazepam is associated with suicidal thoughts and behaviors. Although the incidence is low at about 0.4%, it is significant enough that people taking clonazepam as well as their caretakers should carefully watch for signs of suicidality such as:

  • Thoughts about suicide or dying
  • Attempts to commit suicide
  • New or worse anxiety or depression
  • Trouble sleeping
  • Acting on dangerous impulses
  • Agitation, restlessness, or irritability
  • Panic attacks
  • Other unexplainable changes in mood or behavior

How long do side effects last?

The half-life of clonazepam is 30–40 hours, which means that it takes about five to eight days to clear it from the body. Most minor side effects, however, fade within a day of taking the last dose. Many side effects, such as mental impairment, do get better over time as the body develops a tolerance for the drug. Unfortunately, tolerance means that the medicine becomes less beneficial, as well. 

Most serious side effects fade after the medicine is stopped. However, drug abuse and withdrawal could take weeks, months, or even years to resolve or treat effectively.

Clonazepam contraindications & warnings

All benzodiazepines, including clonazepam, carry similar risks. At the top of the list is the potential for physical dependence, drug abuse, and withdrawal, but problems can be caused by certain pre-existing conditions, too.

Abuse and dependence

The longer clonazepam is taken, the more likely the body will develop dependence and tolerance. Dependence often involves drug cravings and withdrawal symptoms. Tolerance reduces the effects of the drug, requiring larger doses to maintain the desired effect. For these reasons, long-term use of clonazepam is avoided.

Substance abuse is a serious hazard when taking benzodiazepines. About 1–2% of people in the U.S. misuse or have misused a benzodiazepine. Clonazepam abuse can lead to serious side effects, hazardous drug interactions, and potentially life-threatening overdose. 

Clonazepam is only intended as a short-term treatment option, particularly for panic disorder. If clonazepam is taken for longer than two to four weeks, discontinuation can produce withdrawal symptoms that typically last for 10 to 14 days. Clonazepam must be discontinued in a gradually decreasing dose supervised by a healthcare provider to avoid withdrawal. Even with a tapered dose, some withdrawal symptoms may be experienced.

The severity of clonazepam withdrawal will depend on how long the medication has been used, in what doses, and how quickly the medication is discontinued. About 10–15% of patients who have taken a benzodiazepine for over four weeks will experience protracted withdrawal, even if the doses were steadily decreased at the end. These long-term withdrawal effects can last anywhere from six to 18 months after clonazepam has been discontinued.

Overdose

A clonazepam overdose requires immediate medical attention, particularly if clonazepam has been taken with other drugs such as opioids. If an overdose is suspected, call a poison helpline or get emergency medical treatment. Signs of clonazepam overdose include somnolence, confusion, slowed reflexes, muscle weakness, and coma. 

Restrictions

Though Clonazepam is widely prescribed, some people may not be able to take this drug safely. Others may require careful monitoring for side effects.

  • Contraindications: People who are allergic to benzodiazepines will not be given clonazepam. Other benzodiazepines include Valium (diazepam), Ativan (lorazepam), Xanax (alprazolam), and others. Because clonazepam is broken down by the liver, people with severe liver disease will not be able to take clonazepam. Clonazepam is also never given to people with acute closed-angle glaucoma.
  • Substance abuse: Clonazepam use has a high risk of developing into drug misuse and then drug abuse, so healthcare providers are cautious about prescribing it to people with a history of drug or alcohol abuse. They will closely monitor these patients for signs of misuse or diversion. 
  • Depression: People with depression will be monitored for any worsening of the depression or suicidality. 
  • Seizure disorders: Although clonazepam is FDA-approved to treat seizures, it may induce seizures in people who have multiple different types of seizure disorders. These patients may require additional anticonvulsants.
  • Breathing problems: Clonazepam can slow down breathing, so people with lung problems or sleep apnea will need careful monitoring. 
  • Kidney disease: People with kidney dysfunction will be monitored closely to make sure clonazepam by-products aren’t building up in the blood. 
  • Other conditions: Clonazepam can cause excessive salivation, so it is used cautiously in patients who have conditions that cause secretion problems such as Parkinson’s disease and dementia. Clonazepam can also worsen porphyria, which involves difficulty making heme in the blood. 

Pregnancy and nursing

Women should tell the prescribing healthcare provider about pregnancy or pregnancy plans. There are no studies of clonazepam use in pregnant women, but healthcare professionals are cautious about using clonazepam during pregnancy and will discuss the risks and benefits with the patient. When clonazepam is taken in the last trimester, however, newborns are more likely to be sedated, have difficulty breathing, or lack muscle tone (“floppy baby syndrome”).
Clonazepam can be used cautiously in women who are breastfeeding. When taken by the mother, clonazepam is present in breast milk. Nursing babies should be monitored for sedation, weight gain, and developmental milestones.

Children

Clonazepam is FDA-approved for use in children to treat seizure disorders, but not for anxiety disorders or other psychiatric problems. Healthcare providers are advised, however, to monitor the child for any developmental problems while taking clonazepam.

Seniors

Clonazepam is given to older patients at the same doses as younger adults, but the starting dose is often smaller. Because liver problems increase the risk of side effects, healthcare providers will closely monitor the adverse effects of clonazepam in an older patient. However, the Beers Criteria considers all benzodiazepines to be potentially inappropriate medications for older patients, so some doctors avoid prescribing clonazepam to older patients. 

Clonazepam interactions

Clonazepam can cause problems when taken with certain over-the-counter or prescription drugs. While most clonazepam drug interactions are minor, some can be hazardous or even life-threatening.

  • Drugs that lower the seizure threshold: For people taking clonazepam for a seizure disorder, some drugs that lower the seizure threshold are never prescribed at the same time. These include the antidepressants Wellbutrin (bupropion) and maprotiline, the muscle disorder medications amifampridine and dalfampridine, and the gastric motility drug metoclopramide. Other drugs that lower the seizure threshold are used cautiously in patients with seizure disorders who are taking clonazepam.
  • Opioids: The FDA has placed a black-box warning on clonazepam that states that opioids should be avoided when taking clonazepam. In addition to sedation and mental impairment, the combination could cause shallow breathing, respiratory depression, and even death. 
  • Central nervous system depressants: Combining clonazepam with central nervous system depressants increases sedation and mental impairment while slowing down breathing. Sedation and mental impairment carry a risk of falls, injuries, and accidents. Slowed breathing could become bad enough to be considered a life-threatening emergency. CNS depressants to avoid include other benzodiazepines, barbiturates, and prescription sleeping pills such as Ambien (zolpidem). Other types of drugs are also CNS depressants, but they are less powerful than opioids, benzodiazepines, and sedatives. These include anticonvulsants, anxiety drugs, antipsychotics, tricyclic antidepressants, and monoamine oxidase inhibitors. People combining these medications with clonazepam should carefully monitor themselves for impairment.

How to avoid clonazepam side effects

Side effects are experienced by most people taking clonazepam. The most common side effects are drowsiness, coordination problems, and behavior changes. Fortunately, most people only take clonazepam for a short period of time. Following a few rules of thumb can make clonazepam treatment easier.

1. Take clonazepam as directed

Follow the healthcare provider’s instructions when taking clonazepam. The dose will vary depending on the condition being treated and it may change during treatment. The healthcare provider may also prescribe a dosing schedule. Take a missed dose when it’s remembered. If it’s almost time for the next dose, skip the missed dose and take the next dose on time, but never take extra medicine to make up for a missed dose.

2. Read the medication guide

Clonazepam is a serious medicine to take. Even generic clonazepam comes with a medication guide with useful information on how to take the drug, side effects, and potential pitfalls. Read this medication guide completely. It will help you identify any problems caused by this medicine. 

3. Tell the doctor about all medical conditions

As with all prescriptions drugs, the best way to avoid side effects is to make sure the prescribing healthcare provider knows about all current and past medical conditions, especially:

  • Liver or kidney problems
  • Lung problems
  • Depression or mood problems
  • Suicidal thoughts or behaviors
  • Porphyria
  • A history of allergic reactions to benzodiazepines
  • Pregnancy or any plans to get pregnant
  • Breastfeeding or any plans to breastfeed

4. Do not stop taking Clonazepam

If clonazepam is not working or the side effects are too burdensome, get medical advice before discontinuing this medicine. Stopping clonazepam suddenly could cause withdrawal effects, which could be severe and long-term. A healthcare provider will prescribe a steadily decreasing dose to minimize the chances of withdrawal.

5. Be careful about driving and other risky activities

Clonazepam causes impairment in most people, including sleepiness, poor coordination, and behavior changes. Everyone taking clonazepam will be advised to take a rest from dangerous activities that require focus and coordination, such as driving, operating machinery, or engaging in risky sports. Once the effects on mental acuity and coordination are understood, only then should people re-engage in these activities. Even then, caution is advised.

6. Avoid alcohol

Avoiding alcohol is a powerful way to minimize clonazepam side effects. Alcohol will only worsen some of clonazepam’s most troublesome side effects, such as severe drowsiness, coordination problems, and trouble breathing. 

7. Safety-proof the home

People taking clonazepam, particularly older adults, are vulnerable to falls, injuries, and accidents. It’s a good idea to make the house as safe as possible before taking clonazepam. Ensure that obstacles like coffee tables or other furniture are out of the way. For older adults, add slip-proof mats to the bath or slippery floors. Adding tables or other stable furniture around chairs can help people get up from a chair to steady themselves. 

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