How Long Does Clonazepam Stay in Your System?

Clonazepam is a popular medication that is most commonly associated with treatment for panic disorder, but the medication was originally developed as a treatment for certain types of seizure disorders.

Today, the medication has a number of applications for different issues with the brain, including epileptic activity and mental illness in the form of anxiety.

It is believed to work by acting on the GABA-benzodiazepine receptor complex in the brain, which improves the amount of GABA in your system.

Because low levels of GABA are linked to anxiety disorders, seizure disorders, pain, and mood disorders, it is thought that clonazepam’s effectiveness lies in its ability to attract this neurotransmitter.

This fast-acting medication is known for being effective at panic attacks, but how long does clonazepam stay in your system?

What is clonazepam?

Clonazepam is an anticonvulsant or antiepileptic drug that is used to prevent and control seizures and also has applications in the treatment of panic attacks.

Clonazepam is part of a class of medications called benzodiazepines, which also includes medications like Ativan (lorazepam), Valium (diazepam), and Xanax (alprazolam).

Sold under the brand name Klonopin, both the brand name and generic forms of the medications are available in oral tablets of varying strengths.

What is clonazepam used to treat?

Clonazepam is FDA-approved for the treatment of certain seizure disorders, including absence seizures or Lennox-Gastaut syndrome, as well as panic disorder, including agoraphobia, in adults.

While other benzodiazepines, such as Ativan, are approved for the treatment of anxiety in general and insomnia, clonazepam is not used for these purposes. 

Absence seizures

Absence seizures are a type of short seizure that typically last less than 15 seconds.

During absence seizures, the brain function is disturbed as a result of abnormal electrical activity, causing the person having the seizure to stare off into space without realizing it.

Absence seizures are caused by overactivity in the brain and typically occur in people under the age of 20, particularly children between the ages of 4 and 12.

Lennox-Gastaut syndrome

Lennox-Gastaut syndrome is a severe type of childhood epilepsy that includes several different types of seizures.

Seizure types commonly associated with Lennox-Gastaut syndrome include tonic, or stiffening, seizures, as well as atonic, or drop, seizures.

Children with Lennox-Gastaut syndrome frequently suffer from intellectual impairment and commonly suffer from behavioral issues that include aggression, hyperactivity, agitation, and autism.

Seizures are difficult to control in people with Lennox-Gastaut syndrome, and although diagnosis of the illness occurs in childhood, many people continue to experience symptoms through adolescence and into their adult years. 

Panic disorder

Panic disorder, sometimes referred to as panic attacks, consists of sudden periods of intense fear and anxiety that cause physical symptoms without the presence of an apparent cause or serious danger.

Some people think they are having a heart attack during a panic attack because the symptoms can feel similar.

Although many people experience one or two panic attacks over the course of their lifetimes, people that experience panic attacks on a recurring basis are diagnosed with panic disorder.

Symptoms of panic attacks include:

  • Sense of impending doom or danger
  • Rapid, pounding heart rate
  • Trembling or shaking
  • Chills
  • Nausea
  • Chest pain
  • Dizziness, lightheadedness or faintness
  • Feeling detached from reality
  • Fear of loss of control 
  • Sweating
  • Shortness of breath or tightness in your throat
  • Hot flashes
  • Abdominal cramping
  • Headache
  • Numbness or tingling sensation

How long does clonazepam stay in your system?

Clonzepam is longer lasting than most other benzodiazepines, although it starts working quickly.

In general, clonazepam starts working in about 20 minutes to an hour and reaches its peak effects between one and four hours after the medication is taken.

Some patients experience the effects of clonazepam for up to 12 hours after taking the medication, while others may experience the effects for closer to six hours.

The half-life of Klonopin is approximately 30 to 40 hours, and the medication can be detected in your system for up to two weeks, depending on the size of your dose. 

What are the benefits of using clonazepam?

Like other benzodiazepines, there are drawbacks to clonazepam use, but there are also many benefits.

Unlike other benzodiazepines like Ativan and Xanax, clonazepam produces calming effects for a longer period of time than the other medications, so it does not need to be taken as often in order to control panic attacks.

It is faster-acting than long-term anxiety medications, such as Lexapro, and is a good solution if a person needs a substantial reduction in their anxiety levels and panic attacks to occur quickly.

When used properly, clonazepam can be very helpful in allowing patients to manage their acute anxiety symptoms or prevent panic attacks, but only if the necessary precautions are taken to avoid dependence.

Clonazepam is occasionally prescribed alongside a more long-term antidepressant or anti-anxiety medication. 

How do I use clonazepam to treat panic disorder?

Clonazepam should only be taken for short periods of time due to the medication’s potential for abuse and dependence.

Typically, clonazepam should not be taken for periods of longer than nine weeks without the supervision of a doctor.

Clonazepam can serve as a kind of “bridge” to help patients manage their anxiety symptoms in the short term while waiting for longer-term anxiety medications to kick in.

Are there any side effects associated with clonazepam?

Common side effects of clonazepam include:

  • Drowsiness
  • Unsteadiness
  • Difficulty thinking or remembering
  • Muscle or joint pain
  • Blurred vision
  • Dizziness
  • Problems with coordination
  • Increased saliva
  • Frequent urination
  • Changes in sex drive or ability

Serious adverse effects requiring medical attention include:

  • Rash
  • Swelling of the eyes, face, lips, tongue, or throat
  • Hoarseness
  • Hives
  • Difficulty breathing or swallowing
  • Difficulty breathing

Symptoms of psychological and/or physical dependence on clonazepam may include:

  • Depression 
  • Muscle weakness
  • Nightmares
  • Body aches
  • Anxiety
  • Sweating
  • Nausea
  • Vomiting 

If you experience an allergic reaction to clonazepam, you should seek medical attention immediately. Symptoms of an allergic reaction include:

  • Trouble breathing or swallowing
  • Swelling of lips, tongue, or face
  • Rash or hives
  • Rapid heartbeat

Does clonazepam come with any warnings for use?

Clonazepam comes with several warnings for use, including increased risk for possible drug interactions.

Medications like clonazepam can cause respiratory depression when taken in large doses, when taken by people with existing respiratory conditions, or when taken with other central nervous system depressants (CNS depressant) prescription drug medications, such as opioids or barbiturates. 

The medication can be addictive and habit-forming, so it should be used for the shortest period of time possible and at the lowest dose in order to control symptoms. 

Using clonazepam can cause an increase in suicidal thoughts or behaviors, particularly in people with depression, so it should be used with caution. Individuals taking antihistamines, those who have liver disease, those taking muscle relaxants, those with narrow angle glaucoma, those taking antifungals, and those taking SSRIs and other antidepressant medications should consult with a health care professional to discuss drug information, possible interactions, and alternative treatment options, even if you’re taking these drugs in low doses. 

Additionally, pregnant women and those breastfeeding should not take clonazepam as it can pass into breast milk.

Are there any withdrawal symptoms associated with clonazepam?

The use of benzodiazepines like clonazepam are known to be habit-forming, and carry a high risk of drug abuse and physical and psychological dependence.

Because of this dependence, stopping the use of clonazepam abruptly and without tapering down the dose of clonazepam gradually can cause physical and psychological withdrawal symptoms to occur as your body detoxes from the medication, and can even be life-threatening. 

The longer you have been taking clonazepam, the more difficult it is to wean off the drug, so patients who have been taking clonazepam regularly for more than two weeks, especially in high doses, should proceed under a healthcare provider’s medical advice in order to prevent withdrawal symptoms from occurring. 

Common physical withdrawal symptoms include:

  • Headache
  • Nausea and vomiting
  • Short-term memory loss
  • Irregular heart rate or heart palpitations
  • Increased blood pressure
  • Dizziness
  • Fatigue
  • Impaired coordination and motor functions
  • Feeling lightheaded
  • Stomach pain
  • Tremors
  • Insomnia
  • Sweating
  • Impaired respiration
  • Blurred vision
  • Muscle spasms and cramps
  • Diarrhea
  • Seizures

Common psychological withdrawal symptoms include:

  • Hallucinations
  • Mental confusion
  • Difficulties concentrating
  • Drastic mood swings
  • Anxiety
  • Depression
  • Lack of motivation
  • Anger and hostility
  • Nightmares
  • Short-term memory lapses
  • Irritability
  • Trouble feeling pleasure
  • Panic
  • Drug cravings
  • Feeling disconnected from reality

Is it possible to overdose on clonazepam?

It is possible to overdose on clonazepam, and overdose is most likely to occur when the medication is taken while drinking alcohol or when used in conjunction with opioid medications.

Benzodiazepines like clonazepam carry a high risk of physical and psychological dependence. Commonly, people start taking the drug at a reasonable dose but become dependent on the calming effects it provides.

They then begin to take more and more of the medication in order to achieve the same calming effect that they first experienced.

The constantly increasing dose can eventually lead to an accidental overdose, which is why clonazepam should only be taken as prescribed and under the supervision of a doctor. 

Signs of a clonazepam overdose include: 

  • Confusion
  • Lightheadedness
  • Slurred speech
  • Feeling restless
  • Extreme drowsiness
  • Loss of balance or coordination
  • Weak or shallow breathing 
  • Slow heartbeats
  • Muscle weakness
  • Coma

Medical attention should immediately be sought in the event of an overdose or possible overdose of clonazepam.

References, Studies and Sources:

author avatar
Angel Rivera
I am a Bilingual (Spanish) Psychiatrist with a mixture of strong clinical skills including Emergency Psychiatry, Consultation Liaison, Forensic Psychiatry, Telepsychiatry and Geriatric Psychiatry training in treatment of the elderly. I have training in EMR records thus very comfortable in working with computers. I served the difficult to treat patients in challenging environments in outpatient and inpatient settings

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