Anatomy of a Drug Test

Ever wonder how drug tests work? I mean think about it – you can eat or inhale something that will later show up in your urine. Doesn’t make a ton of sense unless you understand the chemistry behind drug use… and particularly marijuana. Let us explain.


How can something you smoke or eat end up in your pee? Read on to learn more.

From Weed to Peed (in a cup)

The journey of marijuana…

Step 1 – Trying the Drug

It doesn’t matter if you smoke marijuana or eat it in pot brownies, once marijuana has hit your lips (or your stomach), you’ve used the drug and the chemicals that come with it are in your body.

Step 2 – The drug is absorbed by the blood

When you smoke marijuana, the chemicals first go to your lungs. The main chemical is THC, which is extremely strong and fast-acting. Once the chemicals enter your lungs, they quickly go to the bloodstream. When you eat marijuana (for example, pot brownies), the chemicals first enter your stomach. Although it takes a little longer to enter the blood stream, the chemicals will eventually make it there. It’s said that this “high” actually lasts longer.

Step 3- Blood travels throughout your body

Once the chemicals are in your blood stream, they begin traveling all about your system. They quickly make it to the brain, which is why many experience fast impairment, short-term memory loss and more AKA the “high.”  However the brain isn’t the only place they travel.

Step 4 – Waste is excreted

Just like any chemical (drugs or not) that enters the body, THC circulates through all major organs once it’s in the blood stream. So the process of excreting any waste from your body also applies to chemicals from marijuana. The job of your kidneys is to process waste from the blood stream. While urine is mostly water, it’s also toxins, chemicals and dead blood cells from your body. So, the chemicals from marijuana will show up in your urine. If you’re receiving a hair test or fingernail drug test, chemicals show up because THC was in your blood stream. If you’re wearing a sweat patch, the chemicals will be excreted via your skin.

So – that’s a quick view of the journey of marijuana through your body, and why it shows up on drug tests.

Learn more about marijuana in the body here!

Or, need a drug test in Lawrence, KS? Call us.


  1. This is really interesting. You don’t normally get to see the ins and outs of how a drug test actually works. Thanks for sharing this information, I really enjoyed learning this process.

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