ijuana use disorder.18 People who begin using marijuana before the age of 18 are four to seven times more likely to develop a marijuana use disorder than adults.
Marijuana use disorders are often associated with dependence—in which a person feels withdrawal symptoms when not taking the drug. People who use marijuana frequently often report irritability, mood and sleep difficulties, decreased appetite, cravings, restlessness, and/or various forms of physical discomfort that peak within the first week after quitting and last up to 2 weeks. Marijuana dependence occurs when the brain adapts to large amounts of the drug by reducing the production of and sensitivity to its own endocannabinoid neurotransmitters.
Marijuana use disorder becomes an addiction when the person cannot stop using the drug even though it interferes with many aspects of his or her life. Estimates of the number of people addicted to marijuana are controversial, in part because epidemiological studies of substance use often use dependence as a proxy for addiction even though it is possible to be dependent without being addicted. Those studies suggest that 9% of people who use marijuana will become dependent on it rising to about 17% in those who start using in their teens.
In 2015, about 4.0 million people in the United States met the diagnostic criteria for a marijuana use disorder;3 138,000 voluntarily sought treatment for their marijuana use.
THC, the principal psychoactive constituent of the cannabis plant, has low toxicity. The dose of THC needed to kill 50% of tested rodents is extremely high. Cannabis has not been reported to cause fatal overdose in humans.
Tetrahydrocannabinol, the chemical in marijuana that makes people feel “high,” can stay in the body for several days or even weeks.
The length of time this chemical stays in the body or continues to show in a drug test depends on many factors. These include:
how much body fat a person has
how often they consume the drug
how much someone smokes
the sensitivity of the drug test
Drugs such as alcohol may completely disappear from the body in just a few hours. In comparison, weed lingers much longer.
Drug tests can detect tetrahydrocannabinol, or THC, in urine, blood, and hair for many days after use, while saliva tests can only detect THC for a few hours. This is because of the way the body metabolizes THC.
THC is a lipid-soluble chemical. This means that it binds to fat in the body, which increases the length of time it takes for someone to eliminate THC completely.
Research on the amount of time a test can detect marijuana shows a wide range of averages. Research from 2017 estimates a detection window for a single marijuana cigarette of about 3 days.
The same study emphasizes that detection windows vary and depend on how often a person smokes.
For someone smoking marijuana for the first time, tests may detect it for about 3 days.
In someone who smokes marijuana three or four times per week, the detection window is 5–7 days.
For people who smoke marijuana once a day or more, tests may detect it in their system for 30 days or longer.
Detection windows also depend on the kind of test a person undertakes. General estimates for various marijuana tests are as follows:
Urine tests can detect marijuana in the urine for approximately 3–30 days after use.
Saliva tests can detect marijuana for approximately 24 hours after use. Some saliva tests have detected marijuana for up to 72 hours.
Hair tests are the most sensitive tests, detecting THC for up to 90 days after use. However, these tests are testing the oil in skin that transfers to hair, and so they may occasionally show a false positive. A person who comes into contact with a THC user could, theoretically, test positive on a hair test.
Blood tests can only detect THC for 3–4 hours.
Where Is Cannabis(Marijuana) Legal?
Step 1: Find a Place to Grow
Growing indoors is much more private than growing outdoors and you also get more control over your growth.
Indoor canabis grow can be surprisingly cheap to get started and maintain, especially if you plan on gro