How Long Does Marijuana Last?

The effects of marijuana fade quickly, but the drug can last in the body for weeks and sometimes longer. The amount of time the active ingredients and breakdown products of weed remain in the system can range from a few hours to 90 days, depending on how often or how much marijuana the person has been using.

For example, a single dose of weed can stay in your system for up to 13 days, depending on the type of test used. If you rarely smoke weed or only have a few puffs, it will leave your system more quickly than if you use marijuana frequently or heavily.

Although a number of states in the U.S. have active medical marijuana laws and recreational use of marijuana for adults over the age of 21 is legal in 12 states, Washington, DC, the Northern Mariana Islands, and Guam, the federal government continues to classify marijuana as a Schedule I controlled substance.

The FDA has not yet approved medical marijuana for any medical indication, but it is often prescribed for chronic pain, nausea, HIV, multiple sclerosis, glaucoma, and irritable bowel syndrome (IBS).

How Long Does It Take to Feel the Effects?

The effects of marijuana can vary from person to person. Some people may feel euphoric and relaxed while others feel anxious and paranoid. In other cases, people report feeling "dopey" and experience a loss of interest in activities or an inability to grasp concepts.

The chemical in marijuana that makes you feel "high" is tetrahydrocannabinol, also called delta-9-THC or simply THC. It enters the body's bloodstream rapidly after smoking marijuana.

If weed is ingested orally rather than smoked, it takes longer to be absorbed into the blood, usually from 20 minutes to an hour and a half, but this can vary based on the amount taken as well as physiological factors such as absorption and rates of metabolism and excretion can influence drug concentrations in circulation.

Effects can be far-ranging depending on the strain, method of consumption, and amount and can include the following:

• Dry mouth
• Swollen eyelids
• Bloodshot eyes
• Pleasurable body sensations
• Increased appetite ("the munchies")
• Relaxation
• Stimulation
• Distorted perception (sights, sounds, time, touch)
• Loss of coordination
• Trouble with thinking, memory, and problem-solving
• Increased heart rate

The short-term effects of marijuana on memory, learning, problem-solving, and coordination last for one to two hours, with some lingering effects for up to 24 hours. It's been shown to impair your driving performance for up to three hours, according to the National Highway Safety Administration.

The effects of weed are also influenced by the terpene profiles of a given strain. For instance, citrus terpene profiles tend to be more stimulating, which may be the desired effect, or may contribute to someone feeling anxious.

This variance may contribute to how quickly you feel the effects and what those effects are. THC can interact with alcohol, blood thinners, and anti-anxiety medications, so it's important to discuss your marijuana use with your doctor.

How Long Do Marijuana's Effects Last?

The half-life of marijuana is how long it takes for half of the drug to be metabolized and eliminated from the bloodstream.

THC is rapidly broken down and modified into molecules known as metabolites. At least 80 different metabolites are formed from THC and may have their own effects on the body's endocannabinoid system. These metabolites are stored in body fat and are gradually eliminated from the body through feces and urine.

It takes five to six half-lives for a substance to be almost entirely eliminated. This is why you see advice that one-time use is probably not detectable after five to eight days.

Blood and Saliva

Because marijuana stays in the bloodstream for only a short time, blood tests for marijuana are usually not used. The exceptions are in the case of automobile accidents and some roadside sobriety checkpoints.

Blood or saliva tests can show current intoxication. However, unlike blood alcohol concentration tests, they do not indicate a level of intoxication or impairment.

Hair

Daily or near-daily cannabis consumption is likely, but not always, detectable by a hair test up to three months later. But, the hair test is not reliably able to detect infrequent cannabis use or determine the amount of cannabis used.

Urine

Urine tests for marijuana metabolites also only show recent marijuana use, not current intoxication or impairment. This is because of the time required between use and your body breaking down THC to the metabolites that are eliminated in the urine. Because many employers have a zero-tolerance for drug use, most workplaces use urine tests to detect recent use of drugs.

False Positive Testing

Workplace testing for marijuana might entail first screening the sample with an immunoassay test, known as the EMIT or RIA. If positive results are returned, the sample is again screened with a gas chromatograph-mass spectrometer (GCMS), which is much more accurate and so false positives are rare.

At one time, ibuprofen (sold over-the-counter as Advil, Motrin, and Nuprin) would cause false marijuana positives. But today's tests have been adjusted to eliminate that problem.

In places where marijuana is legal, roadside blood tests have been known to show some false positives in people who had been legally consuming cannabis but were not actively intoxicated at the time of the test. A 2016 report detailed a Belgian policy of testing oral fluid at the roadside that found it decreased these types of false positives.

Factors That Affect Detection Time

The length of time marijuana remains in your body depends on many different factors, including frequency of use, body mass, metabolism, sex, and hydration levels.

Frequency of Use

There is some evidence that the length of time that marijuana remains in the body is affected by how often the person uses marijuana, how much they use, and how long they have been using.

In a 2017 study of 136 people who use cannabis subjected to hair tests, the presence of five cannabinoids, THC, THC-OH, THC-COOH, cannabinol, and cannabidiol, were present in 77% of the heavy users and 39% of the light users.

Sex

Women often metabolize THC at a slightly slower rate since they tend to have higher levels of body fat than male counterparts.

Metabolism

The faster your metabolism, which can be impacted by age, physical activity, and certain health conditions, the faster marijuana will exit your body. 

Body Mass Index (BMI)

THC metabolites are often stored in the fat cells in your body, so the higher your body fat (or BMI), the slower you'll likely be able to metabolize and excrete marijuana.

Hydration

When you're dehydrated, you'll have more concentrations of THC in the body. Flooding yourself with water won't make you pass a drug test, however. Instead, it will dilute it and you'll likely need to retake the test.

Smoking vs. Vaping vs. Edibles

The method of use also impacts the detection time. If marijuana is smoked or vaped, the THC levels in the body will drop faster than if you ingest it. Edibles take longer to break down in the body and leave your system.

How to Get Marijuana Out of Your System

The only way to rid your body of marijuana is to abstain from the drug completely. However, it's important not to detox from any drug, including marijuana, on your own without the help of a medical professional.

The experience of detoxing from marijuana is highly individual and is dependent on a variety of factors—including age, gender, sex, genetics, and history of use. For instance, if you've been using marijuana for an extended period of time, you are more likely to experience severe withdrawal symptoms compared to an occasional user who may not experience any symptoms.

Before you embark on this journey, it's important to seek guidance and also consider whether you'd be comfortable detoxing at home or at a treatment facility. Keep in mind that the risk of detoxing at home can include the risk of relapse without a strong support network in place. A treatment facility can provide the structure needed to sustain sobriety and the support of peers and healthcare professionals to help ease the transition.

Symptoms of Overdose

It is very difficult to physically overdose on marijuana because the lethal dose is so much higher than the effective dose. Very few marijuana overdoses have ever been reported. If someone you know has taken too much marijuana, and that is the only thing they have taken, an overdose is highly unlikely, but that doesn't mean that marijuana is not harmful.

Psychological distress is possible as is impairment of judgment, both of which can lead to hazardous behaviors that can harm yourself and someone else. Although rare, people can experience THC toxicity when using marijuana in high doses, especially in the form of edibles. Symptoms can include:

• Heart arrhythmias
• Psychosis or paranoia (or exacerbation of pre-existing mental health conditions)
• Seizures
• Uncontrollable vomiting

The concept of "set and setting" is also important. Since people who have taken too much marijuana can experience sensory overload, minimizing overstimulating inputs in the environment can help them to relax. Some people are also more affected by marijuana than others.

Getting Help

You may have a prescription for medical marijuana, or you may want to partake of weed or marijuana edibles in states where it is now legal for recreational use at the state level. There is a common perception that you cannot develop a physical dependence on marijuana, but this is not the case. Psychological dependence is also a consideration.

If you discontinue marijuana after regular or heavy use, you may experience symptoms of withdrawal. Signs of marijuana withdrawal include:

• Appetite change
• Cramps or nausea after eating
• Cravings
• Digestion problems
• Headaches
• Mood swings
• Sleep disruption
• Weight gain
• Weight loss

If you find that you can't handle symptoms of withdrawal without relapsing, you may be at risk for a substance use disorder. Do not be afraid to seek out professional support from a mental health professional.

There are therapists who can help you understand your reasons for using. They also can help you determine how cannabis use is impacting your life, and how to develop a plan to stop using if that ends up being the best choice for you.