How Long Do Roofies Stay In One’s System? Rohypnol Drug Test

Last Updated: June 3, 2020

Authored by Roger Weiss, MD

The way Roofies affects a person makes it hard to administer a rohypnol test in time. Consequently, many of those who fall victim to the drug are unaware or unable to prove that the assault has happened. It can be crucial, therefore, to know how to detect Rohypnol in one’s system.

How Long Does Rohypnol Stay In One’s System?


Rohypnol stays in the system for a relatively long time. It is typical for benzodiazepine drugs. The elimination half-life of Roofies is reported to be between 16 and 35 hours.


Rohypnol is a pill with the 64-77% oral absorption rate. The peak concentrations of the drug in a person’s system occur in 30-90 minutes after ingestion. The effects of Roofies last for approximately 12 hours due to the high absorption rate and a prolonged half-life.


For how long Roofies stays in one’s system depends largely on how it is metabolized. Flunitrazepam, the main active component of the drug, is fat-soluble. Rohypnol is metabolized by the liver into its major metabolite 7-aminoflunitrazepam and two minor metabolites: desmethyl-flunitrazepam and 3-hydroxyflunitrazepam. It means that once Rohypnol enters a person’s system, it will have varying effects depending on how much body fat the person has, among other factors.

Rohypnol Detection On Drug Testing

The main issue with performing a Rohypnol drug test is the lasting effects of the drug that prevent a person from getting help soon enough.

When only a residual amount of the drug is left in the person’s system, it is incredibly difficult to identify it. At the same time, the temporary amnesia caused by flunitrazepam can last for a day or longer, preventing the individual from getting tested. The psychological aspect can also play a huge role in the victim’s decision to get a Roofies drug test. Some people might feel embarrassed or worried about legal issues since Rohypnol for medical use are not approved in the US.

If a person decides to get a Rohypnol test within 60 hours after the consumption of the drug, the best option is to collect a urine sample and pass it for testing. Laboratories will search for up to nine specific metabolites associated with Roofies. Alternatively, the person can go to a clinic, explain the situation and receive directions that will best fit their situation.

How To Test For Roofies

The memory-altering effects of Roofies can make it incredibly hard to administer screening in time. There are several options, however, that make it possible to detect the drug in a person’s system even weeks after it was ingested.

Rohypnol Urine Test

Urine testing for Rohypnol is the preferred way to detect the substance when it is possible to administer the test within 60 hours after the consumption of the drug. However, sometimes a Rohypnol urine test might be able to identify the substance days after it was consumed.

rohypnol test

Rohypnol Blood Test

Since blood screening is not frequently administered to detect this substance, some people wonder whether Rohypnol shows up on a blood test at all. In fact, this type of testing can detect concentrations of Roofies that are as low as 4 ng/ml. A Rohypnol blood test can detect the drug 24 hours after it was consumed. This can be incredibly useful when the person needs to prove the involvement of the drug in the sexual assault.

Rohypnol Hair Test

A Roofies hair test can be administered 14 days after the drug was taken. Like the majority of other medications, benzodiazepines like Roofies can be detected in hair for up to 90 days after the ingestion of the drug.

Rohypnol Self-Administered Test

Certain companies offer kits that a person can use to take a sample and then send it back for screening. While this is a valid option for some, it is important to remember that a Roofies test administered by medical professionals is more reliable.

Rohypnol Detection Before And After The Ingestion

Original Rohypnol tablets are odorless and colorless, making the substance hard to detect. The more recent version of Roofies has blue dye in the pills, which is not visible until the tablet is put into a light-colored drink. The drink turns blue if such tablet is dissolved in it. Since the half-life of Roofies is 16-35 hours, the temporary amnesia that a person experiences for approximately a day after the ingestion of the drug can make it hard to do the testing in time to detect the substance. The most reliable Roofies test is the urine screening. Hair samples can also be tested to detect Roofies in the person’s system two weeks after the substance was consumed.

Page Sources

  1. Substance Abuse and Mental Health Services Administration (US); Office of the Surgeon General (US). Facing Addiction in America: The Surgeon General's Report on Alcohol, Drugs, and Health [Internet]. Washington (DC): US Department of Health and Human Services; 2016.
  2. National Institute on Drug Abuse. Drug Facts: Club Drugs (GHB, Ketamine, and Rohypnol). 2014.

Published on: July 4th, 2019

Updated on: June 3rd, 2020

About Author

Roger Weiss, MD

Dr. Roger Weiss is a practicing mental health specialist at the hospital. Dr. Weiss combines his clinical practice and medical writing career since 2009. Apart from these activities, Dr. Weiss also delivers lectures for youth, former addicts, and everyone interested in topics such as substance abuse and treatment.


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