Taking a Marijuana Drug Test: How Long Does Weed Stay in Your System?

Many states are now moving toward legalizing use of cannabis (marijuana), both for medical and personal use. And if you’re one of the 1 in 5 people in the U.S. who use cannabis, you might be wondering how these changes affect employee rights. 

The situation is complex. For example, in states where cannabis is now legal, can employers still make you take a cannabis drug test? And if they can, how long do you need to wait after using cannabis before you take a test?

Here’s what you need to know about cannabis testing and how long cannabis stays in your system.

Is there a drug test for cannabis?

Yes. Drug tests for cannabis include:

• Urine 

• Hair 

• Sweat 

• Blood 

• Saliva 

• Breath 

Unfortunately, many of these tests don’t accurately differentiate between recent use and long-term use. 

How long does weed stay in your system?

How long cannabis stays in your system depends on several factors. Cannabis isn't processed by the body in the same way as alcohol or other substances. It's stored in your fat cells and slowly released by the body over time. So, how long you'll test positive depends on a few things, such as:

• Your body chemistry and metabolism

• Your body fat

• How much cannabis you consume and how often

• The type and sensitivity of the test

Here are estimates of how long cannabis can be detected in your system, based on the type of test:

• Breath test: up to 3 hours

• Blood tests: hours to days for occasional users; up to 30 days for heavy users

• Saliva test: up to 24 hours

• Sweat tests: 7 to 14 days

• Urine test: up to 30 days

• Hair tests: up to 90 days

In general, if you use cannabis frequently, it’ll take longer to leave your system. 

Your body also breaks down THC (tetrahydrocannabinol) — the active part of the plant that causes a high sensation — more slowly when you eat an edible or drink a cannabis beverage. So, that can affect how long cannabis stays in your system, along with how it shows up on a drug test. 

Can you detox from cannabis faster if you have to pass a drug test?

No, there’s no way to get cannabis out of your system faster. 

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You can find various detox methods and products online that supposedly help you get around drug tests. These include detox teas and supplements. But none of them are clinically proven, and they can even be harmful. Even drinking too much water to dilute your urine can be dangerous. 

And, while you can buy kits to help you cheat your drug urine test, these are illegal. Also, most screening programs will be aware of these (and will expect them). 

Do companies still drug test for weed?

In many states, employers still have the right to maintain a drug-free workplace by testing for cannabis before you get the job. That’s the case even if personal and/or medical cannabis is legal in the state. 

That said, several cities and states are taking legal action in this regard. Their laws prohibit most employers from not hiring someone based on a positive cannabis test before they started working there. Also, some local governments have dropped pre-employment cannabis screening as a requirement for public positions (like a government job). 

Can your employer randomly drug test you for THC?

Random drug tests are unannounced drug tests that your employer can make you take to check if you’re working under the influence. Whether or not they can do this depends on where you’re employed, like with pre-employment testing. There’s quite a bit of variability in state laws.

In many states, employers can conduct testing if they have a “reasonable suspicion” about drug use on the job. That means they have reason to suspect that you’re coming to work impaired. 

This could be if they notice:

• Changes in your behavior or speech 

• Possession of drug-related paraphernalia

• Changes in appearance

• Strongly smelling of cannabis

• Falling asleep on the job

However, many employers have faced legal challenges in these situations with claims of discrimination and invasion of privacy. Many of these “signs of drug use” could also be attributed to other health conditions. 

The only way to know for sure whether an employer is legally allowed to conduct a pre-employment THC test is to check your local employment laws. And be sure to read the fine print.

If you’re job seeking, you can also ask a company’s HR representative in advance about the workplace policies. 

What happens if you test positive for THC for a job?

This information may leave you wondering: What should I do if I’m asked to submit to a THC test at work? Is it better to fail a drug test or to refuse?

The answer to this question also, unsurprisingly, depends on your location. Even places that allow employers to require a pre-employment cannabis screening may offer legal protections for people who do use cannabis, especially for medical reasons (more on this below). 

It’s important to note that even if you fail a THC test, your employer may not be able to fire you. For example, employers must offer rehabilitation the first time an employee fails a test in many states, such as Maine, Vermont, and Minnesota. 

Other states, including California, are legally allowed to fire you both for failing and refusing a THC test. Again — and it can’t be stressed enough — your safest bet is to check local laws to learn about the protections you have in your jurisdiction. When in doubt, seek legal counsel.

What if you use cannabis for medical reasons?

Many states have laws that protect employees from discrimination due to their status as a medical cannabis user. In these states, employers can’t refuse you a job or discipline you for using cannabis for medical purposes. They also can’t do these things if you have a patient card that allows you to use medical cannabis. Keep in mind that this is for medical use only, which is different from personal use.

But it’s also important to know that some states’ laws still protect employers’ right to a drug-free workplace. So, an employer may be able to change the job description to restrict duties that someone who uses cannabis for medical purposes can perform.

If you consume cannabis for medical reasons, it’s a good idea to have documentation from a medical professional for your work file in advance of any drug testing issues. If you’re job seeking, you can always ask a company’s HR representative about its policies. And if you’re currently employed, you can ask your HR team about drug testing.

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Written by:

N. Saya Des Marais, MSW

Saya is a masters-level social worker, mental health clinician, trainer, and mental health content writer. She's worked as a therapist and trainer at public schools, community mental health clinics, and digital health start-ups.

Edited by:

Sophie Vergnaud, MD

Sophie Vergnaud, MD, is the Senior Medical Director for GoodRx Health. A pulmonologist and hospitalist, she practiced and taught clinical medicine at hospitals in London for a decade before entering a career in health education and technology.

Reviewed by:

Sarah Gupta, MD

Sarah Gupta, MD, is a licensed physician with a special interest in mental health, sex and gender, eating disorders, and the human microbiome. She is currently board certified by the American Board of Psychiatry and Neurology.

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