How long does weed stay in your system? When different drug tests can detect cannabis

• How long cannabis stays in your body depends on how often you consume it and your metabolism.
• Urine drug tests can detect THC up to 30 days after your last use.

If you use weed and have been asked to take a drug test, you're likely wondering how long it will take for your results to be clean.

It turns out there's no absolute answer to how long it takes for weed to leave your system. That's because detection time depends on various factors, including the type of test, frequency of consumption, and last use of cannabis.

Important: If you use cannabis, you should know it's illegal under federal law even for medical purposes, which means you can still be fired in states where it is legalized for failing a drug test.

Here's what to expect based on the test you take and tips to flush weed out of your system faster.

How long does weed stay in your system?

When determining how long weed will stay in your system, healthcare professionals say it all comes down to frequency and the amount you use.

"How much you consume and how often will influence how long cannabis stays in your system, but it can depend on an individual's metabolism as well," says April Hatch, RN, co-founder of Cannabis Care Team, a nurse-founded Cannabis education group.

When you smoke, vape, or otherwise ingest weed, THC is broken down into several by-products that are stored in various body parts including body fat, the brain, and the heart.

Medical term: THC, or delta-9-tetrahydrocannabinol, is the chemical in weed responsible for making you feel high.

Over time, the byproducts stored in the body are released back into the bloodstream where they're then excreted in urine; but chronic, daily smokers can have a THC build-up that accumulates faster than it can be eliminated.

Important: It takes longer for weed consumed orally, like an edible, to be processed in the body compared to smoking or vaping, but the exact detection window depends on the quantity consumed as well as how often you use it.

Weed usage can generally be divided into three categories:

• Infrequent users (less than twice a week)
• Regular users (several times per week)
• Chronic users (daily)

Cannabis drug tests measure the presence of either THC or THC by-products in your bodily fluids or hair, but how long after consumption a test can detect them depends on the specific type of test.

Here's what you need to know about each type of testing method:

1. Urine test

Urine testing is the most common drug testing method. THC byproducts can be detected in urine for the following amounts of time:

• Infrequent users: One to three days
• Regular users: Seven to 21 days
• Chronic users: 30 days or longer.

2. Blood test

THC content in blood quickly peaks within the first few minutes of smoking weed and then declines within an hour. But if you consume your weed in edible form, you can expect your blood THC content to peak around 3 hours after consumption.

"Blood tests usually detect marijuana for relatively short periods of 1 to 2 days [after last use]," Sternlicht says.

However, studies show some frequent cannabis users' blood will test positive even after seven days of abstinence.

3. Saliva test

Saliva testing is common in workplaces and uses a swab placed between the lower cheek and gum.

Saliva tests can detect THC for up to 24 hours after last consumption in infrequent cannabis users, and up to 30 hours in regular and chronic users.

4. Hair

Hair follicle testing has the longest detection window, or the period weed can be detected after last use.

Hair follicle tests can detect weed for up to 90 days after last consumption, for most users.

How to get weed out of your system

Experts agree the only way to get weed out of your system is to stop using it. And, if you're a chronic smoker, you're likely in for a waiting game.

"There are products and lots of anecdotal stories on what will work, but the only way to truly clean out your system is to stop consuming," Hatch says.

Note: It's a popular misconception that exercising before a drug test can help you pass, but a small 2013 study found cardio exercise actually increased blood THC levels in regular cannabis users, suggesting exercise releases dormant THC from fat stores.

There are plenty of products on the market claiming they can speed up the weed "detox" process, but these claims are unproven and the products can cause dangerous side effects.

Some detox methods that are touted on the internet but may be harmful include:

• High amounts of B vitamins: A 2018 case report found that some patients who took large doses (in some cases, around 3,000 mg per day over one to two days — more than 187 times the recommended daily allowance) of niacin, or vitamin B3, in hopes of passing urine tests suffered from liver damage and other symptoms. The recommended daily allowance of niacin for adults is 16 mg for men and 14 mg for women.
• Large quantities of water: Drinking too much water in a short amount of time can lead to a serious condition called water intoxication. It's best to drink a healthy amount of water daily (about 125 fluid ounces for men and 91 fluid ounces for women).
• Fasting: Skipping meals can cause side effects like low blood sugar and fatigue. Also, a 2014 animal study found that fasting elevated the amount of THC in the blood of rats who were previously treated with the compound. This is because, similar to when you exercise, fasting may cause THC to be released from fat stores.

If you're hoping to undergo a true weed detox, the main thing you'll need is patience. Drinking water, eating healthy, and "sweating it out" are not surefire ways to remove weed from your system.

However, it won't hurt to stay hydrated and eat a healthy diet with lots of fiber. Fiber can be helpful because 65% of cannabis leaves the body via bowel movements and getting enough fiber can help keep you regular. Also, try to get a healthy amount of sleep every night to maintain your metabolism.

Insider's takeaway

Patience is the name of the game when it comes to clearing weed out of your system, and regular cannabis users taking urine tests will likely test positive for weeks longer than less frequent users.

If you use weed and have to pass a drug test, it's best to stop using right away and give yourself plenty of time to let your body detox.