Marijuana refers to the dried leaves, flowers, stems, and seeds from the hemp plant Cannabis sativa, which contains the psychoactive (mind-altering) chemical delta-9-tetrahydrocannabinol (THC), as well as other related compounds. This plant material can also be concentrated in a resin called hashish or a sticky black liquid called hash oil.
Marijuana is the most common illicit drug used in the United States. After a period of decline in the last decade, its use has been increasing among young people since 2007, corresponding to a diminishing perception of the drug’s risks that may be associated with increased public debate over the drug’s legal status. Although the federal government considers it a Schedule I substance (having no medicinal uses and high risk for abuse), some states have legalized it for adult recreational use, and many states have passed laws allowing its use as a treatment for certain medical conditions.
Marijuana is usually smoked in hand-rolled cigarettes (joints) or in pipes or water pipes (bongs). It is also smoked in blunts—cigars that have been emptied of tobacco and refilled with a mixture of marijuana and tobacco. The smoke has a pungent and distinctive, usually sweet-and-sour, odor. Marijuana can also be mixed in food or brewed as a tea.
Signs & Symptoms
Marijuana smoke is an irritant to the lungs, and frequent marijuana smokers can have many of the same respiratory problems experienced by tobacco smokers, such as daily cough and phlegm production, more frequent acute chest illness, and a heightened risk of lung infections.
- Lack of motivation
- Suicidal thoughts
A Success Story
“In high school I initially began to hang around with the crowd that used alcohol and marijuana. I continued using what you would consider “gateway drugs” but I never experienced any negative consequences.
“Then I met prescription drugs. The next several years were filled with law enforcement encounters, a string of jobs, bankruptcy, rehab programs, harder drugs, and eventually I overdosed and spent a week in the hospital near death. But that wasn’t enough for me to stop using.
“Later, alone and broken, I eventually entered Adult & Teen Challenge. Today I can smile and laugh and I have a joy that is not chemically induced. I am grateful for Teen Challenge and everyone that is involved.”
Effects of Use
When marijuana is smoked, THC rapidly passes from the lungs into the bloodstream, which carries the chemical to the brain and other organs throughout the body. It is absorbed more slowly when ingested in food or drink.
Marijuana affects brain development, and when it is used heavily by young people, its effects on thinking and memory may last a long time or even be permanent. A recent study of marijuana users who began using in adolescence revealed substantially reduced connectivity among brain areas responsible for learning and memory. And a large long-term study in New Zealand showed that people who began smoking marijuana heavily in their teens lost an average of 8 points in IQ between age 13 and age 38. Importantly, the lost cognitive abilities were not fully restored in those who quit smoking marijuana as adults. Those who started smoking marijuana in adulthood did not show significant IQ declines.
Marijuana use may have a wide range of effects, particularly on cardiopulmonary and mental health.
Marijuana smoke, like tobacco smoke is an irritant to the lungs. One study found that people who smoke marijuana frequently but do not smoke tobacco have more health problems and miss more days of work than those who don’t smoke marijuana, mainly because of respiratory illnesses. It is not yet known whether marijuana smoking contributes to risk for lung cancer.
Marijuana also raises heart rate by 20-100 percent shortly after smoking; this effect can last up to 3 hours. In one study, it was estimated that marijuana users have a 4.8-fold increase in the risk of heart attack in the first hour after smoking the drug. This risk may be greater in older individuals or in those with cardiac vulnerabilities.
A number of studies have linked chronic marijuana use and mental illness. High doses of marijuana can produce a temporary psychotic reaction (involving hallucinations and paranoia) in some users, and using marijuana can worsen the course of illness in patients with schizophrenia. A series of large studies following users across time also showed a link between marijuana use and later development of psychosis. This relationship was influenced by genetic variables as well as the amount of drug used, drug potency, and the age at which it was first taken—those who start young are at increased risk for later problems.
Marijuana use during pregnancy is associated with increased risk of neurobehavioral problems in babies. Because THC and other compounds in marijuana mimic the body’s own endocannabinoid chemicals, marijuana use by pregnant mothers may alter the developing endocannabinoid system in the brain of the fetus. Consequences for the child may include problems with attention, memory, and problem solving.
Additionally, because it seriously impairs judgment and motor coordination, marijuana contributes to risk of injury or death while driving a car. A recent analysis of data from several studies found that marijuana use more than doubles a driver’s risk of being in an accident. The combination of marijuana and alcohol is worse than either substance alone with respect to driving impairment