Does cannabis show up in a standard drug test?

“I’m going in for a job interview where there may be a drug test. I am wondering how long weed will show in my system?”

Marcus L.

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Many factors influence how long a chemical lingers in the body or how long it shows up in a drug test. These are some of them:

  • the amount of body fat you have
  • how frequently you ingest marijuana
  • the sensitivity of a drug test depends on how much you may smoke/igest

Alcohol and other drugs can vanish from the body in as little as a few hours. Weed, on the other hand, lasts far longer.

Tetrahydrocannabinol, or THC, can be detected in urine, blood, and hair for several days after usage, although saliva tests can only identify THC for a few hours. This is due to the way THC is metabolized in the body.

The short answer: In a standard blood test, marijuana may show for one to two days on average. If you are a heavy consumer it may be detectable in a drug test for as long as 25 days. It is highly variable.

THC is a lipid-soluble molecule that has been verified your system. This implies it binds to fat in the body, increasing lean mass. Check out this HelloMD article on the topic.

Patty J., NP

I can’t answer from a doctor’s perspective, but I have been to the phlebotomist quite a few times and have had my blood work done. No one ever mentioned THC or cannabis and I am quite certain that there was a good amount of THC in my blood during the blood draw. I would imagine, if they are not looking for it, they will not pull it up in a standard test. If however, someone is doing a test specifically for that, to be on the safe side, I would not consume for a month before the test. Hope this helps!

Ryan M.

No, the only way THC will show up in a blood test is if the doctor is testing for it specifically. Since a standard blood test is not looking for the presence of any THC, none will be detected. Hope this helps!

Green Door West

Hi there!

You may be required to take a THC blood test in certain circumstances – particularly if you are in a rehabilitation program or have an employer with strict anti-cannabis rules. However, please keep in mind your “standard blood test” will often not test for THC. It is usually a Complete Blood Count (CBC) panel that will provide diagnostic information on your liver, kidney, and blood cell status. The primary function of this test is to detect diseases.

Typically, cannabis will stay in your system for about 1-2 days after consumption. However, if you are a heavier user, it can stay for up to 7 days or even longer. With that said, variables that can affect how long THC is present in the blood include metabolism, body mass index, and frequency and amount of cannabis consumed. If you are going to have a THC blood test soon, I suggest abstaining from cannabis consumption for three weeks to be safe!

I hope this helps! 🙂

Veronica B.

Hello there!

Like others have mentioned here, THC from cannabis won’t show up in a “standard” blood test, so your employer, doctor, or whoever is requesting the THC blood test would have to be looking for it specifically. Unlike urine tests, blood tests detect the active presence of THC in the bloodstream.

In the case of smoked marijuana, THC peaks rapidly in the first few minutes after inhaling, often to levels above 100 ng/ml in blood plasma. It then declines quickly to single-digit levels within an hour.

High THC levels are therefore a good indication that the subject has smoked marijuana recently. THC can remain at low but detectable levels of 1-2 ng/ml for 8 hours or more without any measurable signs of impairment in one-time users. In chronic users, detectable amounts of blood THC can persist for days.

Check out this article for more information re: THC blood tests.

Melissa P.

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