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

Many states are now moving toward legalizing cannabis use, both for medical and personal use. And some employers, including Amazon, are no longer requiring negative cannabis tests as a condition of employment.

If you use cannabis, you might be wondering how these changes affect employee rights. The situation is very 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.

Can you test for cannabis?

Yes. What’s most commonly detected in a drug test is something called THC-COOH. This is the inactive metabolite of tetrahydrocannabinol (THC), which is the part of cannabis that creates the “high” feeling. If a drug test picks up on this component, that means you’ve consumed THC. But it doesn’t mean that you’re currently intoxicated or impaired from the substance.

Various types of tests are available (see below). But employers most commonly use urine testing. 

You might be wondering about whether cannabidiol (CBD) — which doesn’t get you high — will make you test positive for cannabis. 

It’s possible, but unlikely, that using CBD will cause you to test positive for THC. CBD products are loosely regulated. That means they sometimes contain more THC than they’re legally allowed to. This could affect testing results.

Types of cannabis testing

Urine testing is the most common way for employers to test for substance use, including cannabis. But it’s not the only testing method. Here are all the ways you can test for cannabis use:

• Urine 

• Hair 

• Sweat 

• Blood 

• Saliva 

• Breath 

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But many of these tests don’t accurately differentiate between recent use and long-term use. For example, blood tests can be positive for cannabis for up to 30 days after your last use. Urine and hair tests can also have a positive result for a longer period of time. And, even if a test could correctly identify recent use, it doesn’t accurately identify whether an employee is currently impaired. 

Testing for impairment

Unlike with blood alcohol testing, there’s no test that can accurately determine if a person is impaired by their cannabis use. Despite an increase in how often these are being ordered, even THC-specific blood panels aren’t a reliable way to identify impairment.

Researchers are evaluating breath tests (like an alcohol breathalyzer) to detect if someone is under the influence of THC. But again, even if someone tests positive for THC on a breathalyzer, this isn’t a reliable indicator of impairment. Much more research is needed before breath tests — or any other test — can reliably be used to identify intoxication. 

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Part of the reason for this is that individuals metabolize THC differently. People have different tolerance levels, and the way people respond to cannabis varies widely. There’s no specific “level” of THC in the body that reliably matches with impairment. 

How long does weed stay in your system?

It 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:

• 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: up to 12 hours

• Saliva test: up to 24 hours

• Sweat tests: 7-14 days

• Urine test: up to 30 days

• Hair tests: up to 90 days

Your body breaks down THC more slowly when you eat an edible or drink a cannabis beverage. So, that can affect how long cannabis stays in your system — and how it shows up on a drug test. 

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

Nope. There’s no way to get cannabis out of your system faster. 

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. And 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). 

These states (and districts) include:

• California

• Minnesota

• Nevada 

• New York

• Washington, D.C.

• Washington

Some cities include:

• Atlanta

• Baltimore

• Cleveland

• New York City 

• Philadelphia

These lists aren’t complete and are likely to change over time.

Are there exceptions?

Employers can give pre-employment drug tests for jobs that are considered “safety-sensitive.” In these roles, being under the influence of substances while on the job could affect the health and safety of others. 

Examples of these jobs include: 

• Law enforcement

• Emergency responders

• Trade work

• Commercial driving

So, depending on your profession or role, the state law may not apply to you, and you may be subject to pre-employment drug screening.

Employment in the federal government

The federal government currently classifies cannabis as a Schedule I substance, the highest and most dangerous level, alongside drugs like heroin. So, cannabis is included in pre-employment testing for most federal positions. Similarly, companies that receive federal funding are often required to follow the government’s testing procedures — which would include cannabis tests. 

It’s not clear if that will change if cannabis is reclassified as a Schedule III substance (meaning less dangerous), as was recently proposed. But some federal agencies have already relaxed their screening policies. 

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.

For example, New York doesn't allow drug testing of employees. And Minnesota also prohibits random drug testing except for employees in safety-sensitive positions and professional athletes. In Georgia, employers with a drug-free workplace program can conduct random drug testing on any employee.

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.

Reviewed by:

Mandy Armitage, MD

Mandy Armitage, MD, has combined her interests in clinical medicine with her passion for education and content development for many years. She served as medical director for the health technology companies HealthLoop (now Get Well) and Doximity.

Reviewed by:

Stacia Woodcock, PharmD

Stacia Woodcock, PharmD, is a pharmacy editor for GoodRx. She earned her Doctor of Pharmacy degree from the University of Kentucky and is licensed in New York and Massachusetts.

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If you or someone you know struggles with substance use, help is available. Call SAMHSA’s National Helpline at 1-800-662-HELP (4357) to learn about resources in your area.