Jump to section
Answer About klonopin cl...

How Long Does Klonopin Stay In Your Urine?

Studies report detection times between 9 and 28 days.


Can you let me know how long Klonopin (clonazepam) stays in your urine?

Asked by Elaine On Nov 21, 2018

Answered by
Medical Content Reviewed By PharmacistAnswers Staff

On Nov 21, 2018


Klonopin (clonazepam) has quite a long detection time in the urine, far longer than the half-life of the drug would suggest.

Generally, we can accurately predict how long a drug will be detectable in the urine based on its half-life (which is the time it takes for 50% of a drug to be metabolized) and route of elimination.

Klonopin and associated metabolites are excreted by the kidneys and the half-life is reported to be between 19 and 50 hours.

In typical cases, a drug is considered completely eliminated in 5 to 6 half-lives.

Using the reported half-life of Klonopin, we would assume it would be detectable in the urine for 4 to 12 days.

However, commonly used drug tests don't actually look for clonazepam since less than 2% of this unchanged drug is excreted. Instead, drug tests look for a major metabolite, 7-aminoclonazepam.

Additionally, commonly used enzyme immunoassay based drug tests aren't used to test for 7-aminoclonazepam because they don't reliably detect the drug.

Instead, far more specific mass-spectroscopy tests are used, which generally need far lower drug concentrations to get a positive result. This prolongs detection time.

A variety of studies have reported that detection times for 7-aminoclonazepam range from 9 to 28 days, quite a lot longer than the half-life of clonazepam would suggest.

Section Summary
Less than 2% of Klonopin is excreted in the urine. Therefore, drug tests look for a major metabolite, 7-aminoclonazepam. Studies suggest that 7-aminoclonazepam is detectable in the urine for up to 28 days.

About Klonopin (Clonazepam)

Klonopin (clonazepam) is an oral benzodiazepine used primarily in the management of seizures but is also used for the treatment of anxiety and short-term insomnia.

Klonopin is considered a rapid acting benzodiazepine with an intermediate duration of action.

After taking by mouth, it begins to work in 15-30 minutes and lasts between 6 and 12 hours per dose.

Clonazepam metabolism does not create active metabolites and it is not thought to accumulate in the body. It does produce inactive metabolites (as discussed above).

Klonopin may be taken without regard to food but should be taken with a full glass of water.

About the Pharmacist

Dr. Brian Staiger Pharm.D

Dr. Brian Staiger is a licensed pharmacist in New York State and the founder of PharmacistAnswers.com. He graduated from the University At Buffalo with a Doctor of Pharmacy degree in 2010. He has been featured in numerous publications including the Huffington Post as well as a variety of health and pharmacy-related blogs. Please feel free to reach out to him directly if you have any inquiries or want to connect! He's answered thousands of medication and pharmacy-related questions and he's ready to answer yours! Brian.Staiger@PharmacistAnswers.com Office: 716-389-3076

Recent Questions