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Drug Tests: How Long After Use Are Certain Drugs Detectable?

Our office is often called by people who recently used an illegal drug (i.e. without a valid prescription) and face an employer drug test, a probation officer’s test or were arrested and submitted to a drug test of some sort (urine, blood, hair or saliva).  The question is always, “will the drug be detected?”
Our answer depends upon knowing first what type of drug was ingested and then knowing a bit about the dosage taken, usage history, the person’s age, health and exercise habits, among other things.
Summary in 60 Words or Less:  How long after usage that a drug is detectable varies by the drug.  If you suspect you were given a drug, immediately get on Google and search for a lab that will take a urine and/or blood sample of you for testing.  The results of such a test may help you defend against criminal charges.
The most important concept to understand is a drug’s half-life.  This is the time in which half the blood plasma concentration of the substance is eliminated from the body and thus, from detection.  The drug’s half life is more important in its detection than any other factor such as the age of the user, etc.

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With this in mind, we present the half-lives of some of the more common drugs:
Xanax (Alprazolam) – this drug has a half-life of nine to sixteen hours in a healthy adult.  This means that most people will have fully eliminated the drug from their body and thus detection is impossible after four days’ post-ingestion.
Ativan (Lorazepam) – the half-life of Lorazepam is 12 hours, which means it is completely eliminated from one’s body in about 2.75 days, or two days and eighteen hours.
Hydrocodone – The half-life of Hydrocodone is 3.8 hours for a 10 mg. dose.  However, some sources say peak concentrations in one’s urine happen after eight hours, but that the drug is fully undetectable after 24 hours from ingestion.

Marijuana – THC has a half-life of three to four days because it is stored in the body’s fat cells and is not very water-soluble.  Depending on the quantity and concentration of THC, especially with some of the stronger forms now available, the half-life can be as long as ten to twelve days.  Since most testing for THC is via a urinalysis, and this testing has been perfected over years, it is considered extremely accurate, so accurate that it can detect THC several weeks and even months after someone has ingested THC.

Amphetamine, i.e. Adderall – The half-life of amphetamine is eleven hours, so it is almost undectable after 48 hours.  In chronic users, it is detectable for up to five days after taking it.

Methamphetamine – the half-life of methamphetamine is approximately twelve hours, but it can be detected for one to four days after use.

Cocaine – the half-life of cocaine is only about an hour, but it can be detected up to four days after use.

Heroin – the half-life of heroin is only three to eight minutes, and then is broken down by the body into morphine, which has a half-life of about 3.6 hours.  Morphine can be detected in the blood for up to four days after heroin use.

GHB – GHB has a half-life of 20 to 53 minutes, depending upon the person and the dosage.  Only five percent will remain after two hours.

Ambien – the half-life of Ambien is about two hours.
As suggested above, the half-life varies by the dosage taken, the history of use (tolerance), the user’s age, body size and body-fat, genetics, liver and kidney function (cirrhosis will slow things down), metabolic rate (exercisers clear it out faster) and whether the user was taking other drugs as well.

In providing this information, we wish to make it clear that Greg Hill & Associates is not trying to coach others on illegal use of a controlled substance without being detected by probation, an employer or the police.  Rather, this information is provided because we are frequently asked about this and in some cases, a victim of some crime may claim the suspect (our client) surreptitiously administered a drug to them, or our client’s conduct can be explained as having been influenced by the use of an illegal drug, either voluntarily or involuntarily.

For more information about drug offense issues, please click on the following articles:
  1. What Is Drug Court?  Who Is Eligible and Ineligible?
  2. DUI Based on Being under the Influence of Drugs
  3. Immigration Consequences of a Conviction for a Drug Offense
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