Clonazepam (Klonopin) is a benzodiazepine that is used to treat seizure disorders and panic disorder. Clonazepam can be detected for several days after its use, and its detection times may vary depending on the individual, amount and frequency of use, age and weight, and liver or kidney functioning.
It can be useful to know the elimination and detection times of clonazepam, as this can inform and help with withdrawal management, overdose treatment, and criminal investigations. Clonazepam can be detected in hair, blood, urine, and saliva tests.
| Type of test | Peak detection time | Detection window |
|---|---|---|
| Urine | Within 24 hours after use | Up to 4 days |
| Blood | Around one hour after use | Up to 9 days |
| Saliva | Shortly after use | Up to 5 or 6 days |
| Hair | Days after use | Up to 28 days |
- Clonazepam is a benzodiazepine available as generic and brand-name medications (Klonopin). It is used to treat seizure disorders and panic disorder.
- Clonazepam has a half-life of up to 40 hours, and its effects peak after 1-4 hours.
- Clonazepam can be detected in blood, saliva, urine, and hair tests for several days after use.
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Understanding clonazepam's half-life
Clonazepam (Klonopin) has a half-life of 30 to 40 hours, and it typically takes five half-lives for complete elimination. As such, clonazepam can leave the body entirely within 150-200 hours or 6-9 days. [1]
Clonazepam is a benzodiazepine, available as a generic medication or as a branded medication called Klonopin. It is approved to treat panic disorder and seizure disorders and may be used off-label for other purposes. [2] Generic clonazepam and Klonopin are available as an immediate-release tablet in 0.5 mg, 1 mg, and 2 mg strengths, and as an orally disintegrating tablet in 0.125 mg, 0.25 mg, 0.5 mg, 1 mg, and 2 mg strengths. A typical daily dose of clonazepam is up to 20 mg per day for seizure disorders and up to 4 mg per day for panic disorder. [2]
Clonazepam is metabolized by the liver and eliminated mostly by the kidneys. The half-life of clonazepam is 30-40 hours, although this can vary and may be longer following prolonged use. [1]
How long do the effects of clonazepam last?
Clonazepam has sedating, calming, and muscle-relaxing effects. After administration, the effects can be felt within 20-60 minutes and are at their peak in one to four hours. Due to its long half-life, the effects may continue for many hours. [3]
Detection windows across testing methods
Clonazepam can be detected in urine, saliva, hair, and blood tests. Tests might be used in the workplace, roadside, during criminal investigations, or during substance use treatment.
Urine tests
Clonazepam can be detected in urine within 24 hours after use and for up to four days. [4]
Blood tests
Clonazepam can be detected in blood within one hour of use and for up to nine days. [2]
Saliva tests
Saliva tests can detect clonazepam shortly after use and for up to five or six days. [5]
Hair tests
Hair tests can detect clonazepam a few days after use and for up to 28 days. [6]
Factors influencing clonazepam's metabolism and elimination
Various factors can impact the metabolism, elimination, and detection times of clonazepam, including: [2]
- Age and weight
- Liver and kidney functioning
- Amount and frequency of use
- Other substance or medication use
- Other health issues
Considerations for dosing schedules and discontinuation
Due to its sedating effects, clonazepam treatment should be commenced gradually. It is recommended to start with a low dose of 0.25 mg to 0.5 mg doses taken two or three times per day. The dose can be increased every three days in small increments until reaching a therapeutic dose, and symptoms are controlled. [2]
Benzodiazepines, including clonazepam, have a high risk of physical dependence, addiction, and abuse. Dependence can develop quickly, sometimes occurring within weeks of treatment. Because of this, clonazepam treatment should not continue for longer than necessary. Klonopin is classified as a Schedule IV substance by the Drug Enforcement Administration (DEA).
For patients requiring longer-term treatment, the prescribing doctor should conduct regular reviews and discontinue treatment when appropriate. Discontinuing clonazepam can cause withdrawal symptoms, which can be more severe in those who have used clonazepam for prolonged periods and in higher doses. [7]
As such, clonazepam treatment will be gradually reduced to reduce the risk of withdrawal symptoms. This may be small dose reductions of 0.125 mg per dose, implemented every three days until complete discontinuation. [2]
Klonopin withdrawal and timeline
Withdrawal symptoms are likely to be more severe after prolonged or excessive use of clonazepam. Milder withdrawal symptoms are common after weeks or months of therapeutic use. Because of this, abrupt discontinuation should be avoided, and doses should be gradually reduced. [1] People who have used clonazepam in high doses and for prolonged periods may require professional advice and treatment to prevent or reduce severe withdrawal symptoms.
Due to its long half-life, clonazepam withdrawal symptoms can take a few days to emerge after reduced or stopped use. They are likely to be at their most severe in the first week or two, after which they will begin to alleviate. [7]
Klonopin (clonazepam) withdrawal symptoms can include: [2]
- Convulsions or seizures
- Psychotic symptoms, including hallucinations
- Extreme changes in mood and behavior
- Shaking
- Cramps
- Low mood
- Anxiety
- Sleep difficulties
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