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How Long Does Klonopin Stay in Your System?

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Last Updated - 6/17/2022

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Klonopin is the brand name for clonazepam, which is a prescription benzodiazepine. Because the length of time that Klonopin stays in the system can vary depending on factors like metabolism, the extent of use and length of use, it can take anywhere from four to 14 days to leave the system completely. However, Klonopin may be detectable on some drug tests for longer than 14 days depending on the test.

You may be tested for Klonopin in certain medical situations and also during legal proceedings. Different tests can be used based on the situation.

How Long Does it Take for Klonopin to Kick In?

Klonopin starts working in approximately 20–40 minutes for most people. It may take longer to start working if taken with a large meal or for those who have a high tolerance. Taking it on an empty stomach may make it kick in quicker.

How Long Does Klonopin Last?

The effects of Klonopin can last as long as 12 hours. Klonopin accumulates in the body, and taking a lot of the medication can cause doses to “stack.” Taking high doses of Klonopin can cause it to stay in the system for longer.

Klonopin “peaks” after about 1–4 hours, and this is when a person will feel the strongest effects. This also comes with the greatest risk of side effects, like confusion, dizziness, and drowsiness.

Klonopin Half-Life

The half-life of a substance is the amount of time it takes for half of the drug to be eliminated from a person’s system. The half-life of Klonopin is between 20–60 hours.

Most drugs are completely eliminated from the body within five half-lives. With a half-life this long, it can take about 4–13 days to metabolize in the body completely.

Compared to other benzodiazepines, Klonopin has a long half-life. Benzos with long half-lives are more effective for treating seizures, while benzos with short half-lives should be used to manage agitation and panic. Moderate half-life benzos may be more useful for insomnia treatment.

How Long Does Clonazepam Stay in Your System?

Klonopin drug tests do not look specifically for Klonopin but instead look for shared benzodiazepine metabolites. Drug tests are most effective at detecting metabolites of other benzodiazepines like chlordiazepoxide, diazepam, oxazepam and temazepam.

While Klonopin is detectable in drug tests, it tends to produce a high rate of false negatives. Drug tests have a harder time picking up Klonopin use because it has a unique set of metabolites that are not specifically tested in drug tests.

Klonopin drug test detection times range from a few weeks to over a month, depending on the type of test.

How Long Does Klonopin Stay in Your Urine?

Benzodiazepines are detectable in urine for over 30 days. However, clonazepam is probably detectable for much less time because benzodiazepine tests are not looking for the active metabolite 7-aminoclonazepam. Short-acting benzodiazepines are only detectable for one day, so the detection time will vary between 1–30 days. There’s also a high rate of false negatives.

How Long Does Klonopin Stay in Your Blood?

Detection in the blood is based on the drug’s half-life. For people with normal metabolism, the detection window is 4–13 days.

How Long Does Klonopin Stay in Your Saliva?

Klonopin is detectable in saliva drug tests for approximately 5–6 days. However, saliva tests for benzodiazepines are fairly uncommon and must be specially ordered.

How Long Does Klonopin Stay in Your Hair?

Hair tests measure the deposition of the drug into growing hair, so the detection window is based on how fast hair grows. Hair tests take three months of hair growth, or 1.5 inches, and can usually detect Klonopin use in the past 90 days.

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Klonopin and Breastfeeding

An infant that breastfeeds while the mother is taking clonazepam will receive about 2.5% of the mother’s dose. Another study showed that 10 out of 11 breastfed infants had no detectable clonazepam in their system even when the mother was taking Klonopin.

If you take Klonopin, speak with your physician if you are thinking about becoming pregnant or breastfeeding.

Because of its long half-life, Klonopin will likely be present in breastmilk for 1–2 weeks after taking a dose. In several small studies, clonazepam was detectable in the infant several days after drinking breastmilk from a mother taking Klonopin.

Factors Affecting How Long Klonopin Stays in Your System

Clonazepam stays in the body for at least 13 days, but this window can change based on several factors.

Heavy and frequent use increases detection times, and extended-release formulations may be detectable for longer periods. Klonopin will also stay in the system longer for older people and those with liver problems.

Other factors that affect how long Klonopin stays in your system include:

  • Amount used
  • Age
  • Frequency of use
  • Formulation
  • Method of use
  • Overall health

Klonopin is broken down by the liver. Because of this, people with liver dysfunction may metabolize Klonopin more slowly, meaning that it may stay in their system longer. The only way to remove Klonopin from the body is time. The body must metabolize and remove it naturally. There is no safe and healthy way to speed up this process.

False Positives for Klonopin

The following drugs are known to cause false-positive benzodiazepine results:

  • Efavirenz
  • Oxaprozin
  • Sertraline

The above drugs can give a false positive for benzodiazepine tests, and not just for clonazepam.

False positives happen because the structure of the “false positive” is similar to the metabolite that is being tested for. In this case, the above drugs have either a similar chemical structure or a similar 3D shape to the benzodiazepine metabolite being tested for.

If a drug test returns positive, it will be sent to another lab to confirm the positive results. The specimen will be tested with gas chromatography/mass spectrometry (GC-MS). GC-MS is sensitive and specific and can detect the “fingerprint” of individual drugs.

Klonopin has a high false-negative rate and may not show up on tests for benzodiazepines. False negatives are more likely to occur with lower and less frequent use of Klonopin.

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Klonopin Withdrawal

All benzodiazepines have the potential to induce withdrawal symptoms once use is stopped. These symptoms can occur in anyone who has developed physical dependence.

Dependence occurs when Klonopin use has changed the structure of neurons in the central nervous system (CNS). The body does this to compensate for steady doses of Klonopin and to help maintain normal bodily functions.

When Klonopin is suddenly stopped, then the body tries to revert to normal functioning and withdrawal symptoms happen during this process. Common benzodiazepine withdrawal symptoms include:

  • Anxiety
  • Trouble sleeping
  • Restlessness
  • Agitation
  • Concentration problems
  • Muscle aches
  • Irritability
  • Memory issues

Since Klonopin is a long-acting drug, withdrawal symptoms may not start until 2–7 days after the last dose. Symptoms can last as long as 2–8 weeks and even longer in people who have used the drug for several years.

Medical Detox for Klonopin Addiction

Medical detox is advised for people with a Klonopin use disorder. Detox is the period where the drug is leaving the body and withdrawal symptoms occur. Since benzodiazepine withdrawal can last so long, detox may continue after the drug is metabolized.

Medical detox can help people go through withdrawal more comfortably and safely. Withdrawal symptoms can lead to relapse because they are so uncomfortable, so medical supervision can ensure this does not happen.

People withdrawing from benzodiazepines have a high risk of seizures and therefore withdrawal can be dangerous or fatal. During medical detox, the medical team may use a tapering strategy to slowly lower the dose of Klonopin, which can lower the risk of severe withdrawal effects.

If you or someone you know needs help with a Klonopin addiction, contact The Recovery Village Ridgefield. We have teams of addiction professionals that can help you learn about treatment options that best fit your needs. Give us a call today.


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