How Long Does Klonopin Stay in Your System?

how long does klonopin stay in the system

How Long Does Klonopin (Clonazepam) Stay in Your System?

Klonopin is a brand-name medication containing clonazepam, a benzodiazepine prescription drug that is used to manage anxiety, panic attacks, and certain types of seizure disorders.[1] Like many other benzodiazepines, it is also a popular drug of abuse, but compared to other benzodiazepines, though, Klonopin is a long-acting drug that has a very long half-life and can stay in your system for weeks.

Some studies show that Klonopin is detected in urine for up to a month after the last use, but in most people, a single dose will be eliminated from the body within six to nine days. Some drug tests, such as hair tests, can detect Klonopin use for up to 90 days after your last dose.

If you are prescribed Klonopin for a health condition and are taking your medication as prescribed, you have nothing to worry about. Even if an employer makes you take a drug test, you have a prescription to justify your use. However, if you are abusing Klonopin or addicted to the drug, you may be worried about passing a drug test or finding out when your withdrawal symptoms will begin. 

How Long Do The Side Effects of Klonopin Last?

Klonopin works by enhancing the activity of gamma-aminobutyric acid (GABA), an inhibitory neurotransmitter that helps regulate the central nervous system (CNS). While this is effective in managing anxiety disorders, panic attacks, and certain types of seizures, Klonopin (clonazepam) can also produce side effects, such as:

  • Drowsiness
  • Dizziness
  • Weakness
  • Unsteadiness
  • Changes in appetite
  • Dry mouth
  • Headache
  • Nausea
  • Blurred vision
  • Constipation

Less common but more serious side effects of Klonopin can include:

  • Severe drowsiness or confusion
  • Difficulty breathing
  • Hallucinations
  • Severe mood changes
  • Suicidal thoughts or actions
  • Seizures
  • Allergic reactions (including hives, rash, and difficulty breathing)
  • Yellowing of the skin or eyes (jaundice)

Klonopin is intended to be taken by mouth. The effects begin to appear after one hour and peak between one and four hours. After 4-6 hours, the effects will slowly wear off. However, Klonopin can be detected in your system for much longer than its effects last.

What is the Half-Life of Klonopin (Clonazepam)

The elimination half-life of a drug refers to how long it takes for half of a single dose of a substance to leave the body. Understanding the half-life of a drug can help you determine when your withdrawal symptoms will begin, whether or not it’s safe to take another dose, and how long a drug stays in your system.

Clonazepam has a fairly long elimination half-life of 30 to 40 hours, so it can take more than two days for just half of your dose of Klonopin to leave your system.[1] 

It usually takes four to five half-lives for a drug to leave your system completely. Based on a 30-40 hour half-life, Klonopin can stay in the body for six to nine days after you stop taking the drug. Clonazepam and its primary metabolite, 7-amino-clonazepam, are detectable in urine for four or more days after the last time you used the drug.

Factors that Influence How Long Klonopin Stays in Your System

Klonopin can remain in some people’s systems longer than others. This is because there are several variables that dictate how long it takes your body to metabolize and eliminate the drug.[2] These variables include:


factors that influence how long klonopin stays in your system infographic


  • Age, weight, and metabolism – People who are young, of healthy weight, and have a healthy metabolism are more likely to metabolize substances faster and pass a drug test faster.
  • Liver function – Benzodiazepines are metabolized in the liver. Poor liver function or liver disease can slow down the metabolic process.
  • Dosage – A higher dose of the medication will stay in your system for longer than a small dose.
  • Frequency and duration of use – The longer and more often you take Klonopin, the longer it will stay in your system.
  • Polydrug abuse – Some substances, such as alcohol, can slow down or speed up the elimination half-life of Klonopin. As a result, using other drugs with the medication can affect how long it remains in your body.
  • pH of urine – When urine is more acidic, Klonopin is less soluble and is more likely to stay in the system longer. If someone has acidic urine, Klonopin may remain detectable for a longer period of time in a urine test compared to someone with alkaline urine. 

Because of all of these independent variables, it can be difficult to say just how long clonazepam stays in your system.

How Long Will Klonopin Show Up on a Drug Test?


how long does klonopin show up on a drug test infographic


Similar to other benzodiazepine medications, Klonopin (clonazepam) can be detected on a standard drug test. If you have to take a drug test for employment or another reason and are taking Klonopin as prescribed by your physician, be sure to bring a doctor’s note with you when you take the drug test.

Different types of drug tests have different detection windows. While Klonopin may be detected in your urine for four to six days after consumption, it can be detected in your hair follicle for up to 90 days after your last dose.

The following are estimates as to how long Klonopin can be detected in various parts of your body.


Urine tests are the most commonly used type of drug test because they are practical, affordable, and accurate. If you have to take a urine test, you will be provided with a sample cup, basic instructions, and a bathroom stall. You’ll be asked to urinate in the cup while a test administrator is in the restroom with you. Klonopin can produce a positive result on a urine test for 4-6 days or more depending on the extent of your Klonopin use. In chronic, heavy users, Klonopin can be detected in the urine for up to a month.


Blood tests are typically only used in medical settings because they are fairly invasive and have to be administered by a healthcare professional. Klonopin metabolites can stay in your blood for up to 5-6 days.


Saliva testing is considered a very non-invasive drug testing method that requires very little training or effort. However, saliva tests have a fairly short detection window. A saliva test can detect Klonopin in your system for 5-6 days after your last dose.


As you use drugs, they can leave behind certain markers in the hair that can stay detectable for several months. Hair tests have the longest detection window of all and are able to detect drugs including Klonopin in your body for up to three months (90 days) after your last dose.

How to Detox from Klonopin Safely

Klonopin is a Schedule IV controlled substance meaning there is potential for abuse and dependence. Taking the medication regularly on a long-term basis can result in tolerance and physical dependence. In some cases, a physical dependence can develop after just 2 weeks of taking the drug each day.

Stopping Klonopin suddenly is dangerous and can result in life-threatening symptoms of withdrawal. If you have been taking Klonopin regularly, it’s important to speak with your doctor about tapering off of the substance. Or, if you are struggling with addiction, you may be better off seeking help from a licensed drug and alcohol rehab center.

Symptoms of Klonopin withdrawal include:[3]

klonopin withdrawal symptoms
  • Nausea
  • Stomach aches
  • Muscle cramps
  • Tremors or shaking
  • Anxiety
  • Panic
  • Sweating
  • Insomnia
  • Restlessness
  • Agitation
  • Hallucinations
  • Seizures

Since Klonopin has such a long half-life, withdrawal symptoms may not appear for up to a week. As a result, you may stop taking Klonopin and think that you aren’t dependent on it, but become sick a week later.

Symptoms of withdrawal last for 2-3 weeks. Peak symptoms usually occur during the second week and begin subsiding after 3-4 weeks. Due to the long withdrawal timeline, it’s encouraged to detox under professional guidance.

The safest way to detox from this medication is to slowly taper off it with the help of a medical professional or to get help from a medical detox facility.

Signs of Klonopin Overdose

Taking too much Klonopin at once or taking your dose too frequently can result in an overdose. Risk factors such as mixing Klonopin with other drugs or being addicted to the medication may increase the risk of overdose. Common signs of a Klonopin overdose are:

  • Extreme drowsiness
  • Confusion
  • Slurred speech
  • Impaired coordination
  • Weakness
  • Respiratory depression (slow, shallow breathing)
  • Blurred vision
  • Unresponsiveness
  • Low blood pressure
  • Slowed heart rate
  • Pale skin
  • Nausea and vomiting
  • Blue tint to lips or fingernails (cyanosis)
  • Coma

If you suspect someone may be experiencing a Klonopin overdose, it’s crucial to call 911 or seek immediate medical attention.

Find Help for Klonopin Abuse and Addiction Today

Attempting to overcome Klonopin addiction on your own can be dangerous. Thankfully, there is help available.

At Moving Mountains Recovery Center, we can connect you with a local detox facility and we’ll be there for you to teach you how to stay sober after you’ve detoxed. Our program is designed to help you find life so full of passion that there is no room left for substance abuse. Take the first step by contacting us today. A team member is here to assist.


  1. Food and Drug Administration (FDA): KLONOPIN TABLETS, Retrieved from,020813s009lbl.pdf
  2. National Library of Medicine: A Case Report of Clonazepam Dependence, Retrieved from
  3. National Library of Medicine: The benzodiazepine withdrawal syndrome, Retrieved from
how long does klonopin show on a drug test

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