Marijuana

Strength and Potency

The amount of THC in marijuana has increased over the past few decades. In the early 1990s, the average THC content in marijuana was about 3.74 percent. In 2013, it was almost 10 percent, and much higher in some products such as oils and other extracts (see below).1 Scientists do not yet know what this increase in potency means for a person’s health. It may cause users to take in higher amounts of THC – which could lead to greater health risks including increased risk of addiction, or they may adjust how they consume marijuana (by smoking or eating less) to compensate for the greater potency. There have been reports of people seeking help in emergency rooms with symptoms, including psychosis (having false thoughts or seeing or hearing things that aren't there), after consuming high concentrations of THC.

Marijuana Extracts

Smoking extracts and resins from the marijuana plant with high levels of THC is on the rise. There are several forms of these extracts, such as hash oil, budder, wax, and shatter. These resins have 3 to 5 times more THC than the plant itself. Smoking or vaping it (also called dabbing) can deliver dangerous amounts of THC to users, and has led some people to seek treatment in the emergency room. There have also been reports of people injured in fires and explosions caused by attempts to extract hash oil from marijuana leaves using butane (lighter fluid).

2. How is marijuana used?

Some people smoke marijuana in hand-rolled cigarettes called joints. Many use glass pipes, water pipes called bongs, or marijuana cigars called blunts (often made by slicing open cigars and replacing some or all of the tobacco with marijuana). To avoid inhaling smoke, some people are using vaporizers. These devices pull the active ingredients (including THC) from the marijuana into the vapor. A person then inhales the vapor, not the smoke. Some vaporizers use a marijuana liquid extract. Marijuana can also be brewed as tea or cooked into food, sometimes called edibles—such as brownies, cookies, or candy.

These concentrated extracts made from the marijuana plant should not be confused with “synthetic marijuana,” sometimes called “K2,” “Spice,” or “herbal incense.” These synthetic drugs are man-made chemicals similar to THC but often much stronger and very dangerous. Unlike marijuana, their use sometimes directly results in overdose deaths. Learn more about "synthetic marijuana”.

Most of the cannabinoid receptors are found in parts of the brain that influence pleasure, memory, thinking, concentration, sensory and time perception, and coordinated movement. Marijuana activates the endocannabinoid system, which causes the pleasurable feelings or "high" and stimulates the release of dopamine in the brain's reward centers, reinforcing the behavior. Other effects include changes in perceptions and mood, lack of coordination, difficulty with thinking and problem solving, and disrupted learning and memory.

Certain parts of the brain have a lot of cannabinoid receptors. These areas are the hippocampus, the cerebellum, the basal ganglia, and the cerebral cortex. (Learn more about these areas and how THC affects them.) As a result, marijuana affects these functions:

• Learning and memory. The hippocampus plays a critical role in certain types of learning. Disrupting its normal functioning can lead to problems studying, learning new things, and recalling recent events. Chronic marijuaua use disorder, that begins in adolescence, is associated with a loss of IQ points, as compared with people who don't use marijuana during their teen years.3 However, two recent twin studies suggest that this decline is related to other risk factors (e.g., genetics, family, and environment), not by marijuana use itself.4
• Coordination. THC affects the cerebellum, the area of our brain that controls balance and coordination, and the basal ganglia, another part of the brain that helps control movement. These effects can influence performance in such activities as sports, driving, and video games.
• Judgment. Since THC affects areas of the frontal cortex involved in decision making, using it can make you more likely to engage in risky behavior, such as unprotected sex or getting in a car with someone who’s been drinking or is high on marijuana.

4. What happens to you body when you use marijuana?

Within a few minutes after inhaling marijuana smoke, a person’s heart rate speeds up, the bronchial passages (the pipes that let air in and out of your lungs) relax and become enlarged, and blood vessels in the eyes expand, making the eyes look red. While these and other effects seem harmless, they can take a toll on the body.

• Increased heart rate. When someone uses marijuana, heart rate—normally 70 to 80 beats per minute—may increase by 20 to 50 beats per minute or, in some cases, even double. This effect can be greater if other drugs are taken with marijuana. The increased heart rate forces the heart to work extra hard to keep up.
• Respiratory (lung and breathing) problems. Smoke from marijuana irritates the lungs, and can cause a chronic cough—effects similar to those from regular cigarettes. While research has not found a strong association between marijuana and lung cancer, many people who smoke marijuana also smoke cigarettes, which do cause cancer. And, some studies have suggested that smoking marijuana could make it harder to quit cigarette smoking.
• Increased risk for mental health problems. Marijuana use has been linked with depression and anxiety, as well as suicidal thoughts among adolescents. In addition, research has suggested that in people with a genetic risk for developing schizophrenia, smoking marijuana during adolescence may increase the risk for developing psychosis and for it developing at an earlier age. Researchers are still studying the relationship between these mental health problems and marijuana use.
• Increased risk of problems for an unborn baby. Marijuana use during pregnancy is linked to lower birth weight and increased risk of behavioral problems in babies.

5. Is marijuana addictive?

Yes, marijuana can be addictive. Someone who regularly uses marijuana may continue to use it despite negative consequences in their life.

Approximately 10 percent of users may develop what is called a marijuana use disorder—problems with their health, school, friendships, family or other conflicts in their life. A serious substance use disorder is commonly called an addiction. The person can’t stop using marijuana even though it gets in the way of daily life. People who begin using marijuana before the age of 18 are 4–7 times more likely than adults to develop a marijuana use disorder.

What causes one person to become addicted to marijuana while another does not depends on many factors—including their family history (genetics), the age they start using, whether they also use other drugs, their family and friend relationships, and whether they take part in positive activities like school or sports (environment). More research needs to be done to determine whether people who use marijuana for medical reasons are at the same risk for addiction as those who use it recreationally.

Watch the Swiss Cheese Model of Drug Addiction and learn why some people become who use drugs get addicted and others do not.

People who use marijuana may feel a mild withdrawal when they stop using the drug. Withdrawal symptoms may include:

• irritability
• sleeplessness
• lack of appetite, which can lead to weight loss
• anxiety
• drug cravings

These effects can last for several days to a few weeks after drug use is stopped. Relapse (returning to the drug after you’ve quit) is common during this period because people may crave the drug to relieve these symptoms.

6. Life Lessons Told Through Comics