What is marijuana? Quite simply, it is a combination of the flower buds, stems, and leaves of the Cannabis sativa plant. It contains delta 9-tetrahydracannabinol (THC) which is the drug’s intoxication chemical as well as at least 500 different chemicals—many of them carcinogenic. Marijuana also contains cannabidiol (CBD) that serves to counteract THC effects. These compounds can affect your body and mind in several ways.

Prevalence of marijuana use in the US

While marijuana—also known as pot, weed, grass, and other slang terms—can be smoked, vaporized, eaten, brewed, and “ingested” topically, the majority of people smoke it. According to a 2010 National Survey on Drug Use and Health (NSDUH), as many as 17.4 million Americans admitted to using marijuana within the past month. A 2016 Gallup Poll found that one out of eight people smoke marijuana while 43 percent of adults have admitted trying it. Today, this number is presumed even higher as many states and Washington, D.C. have legalized marijuana in some fashion, whether medicinally, recreationally, or both.

Over the years, the average THC content has increased from less than one percent in 1972 to nearly four percent in 1990 to as much as 13 percent in 2010. These amounts continue to rise. Today, some marijuana contains 30 percent or more THC. Increased potency complicates determining accurate long- and short-term effects of the drug.

Marijuana ingestion

When marijuana is smoked, THC is absorbed through the lungs and into the bloodstream. Marijuana can be smoked in cigarette form (a joint) or through bongs, glass pipes, bubblers, blunts, and other paraphernalia. More recently, vaporization—or vaping—has emerged as a smokeless delivery system. Because the marijuana is heated at a lower temperature, studies suggest that this method is healthier than regular smoking because the user inhales fewer toxic compounds and carbon monoxide. Either way, smoking marijuana is the quickest way to achieve the desired result—a euphoric high. Generally, your high will peak in about 30 minutes and then taper off between one and four hours.

Marijuana can also be ingested orally. The effects are slower because the THC must first pass through the digestive system to reach the bloodstream. Thus, effects may take up to two hours; however, they will generally last longer—as many as eight hours—than smoking. Cannabis can also be added into baked goods, candies, and even brewed in a tea.

Marijuana and your body

Despite being a Schedule I controlled substance, marijuana does have some medical benefits such relieving chronic pain, reducing the effects of glaucoma, alleviating nausea, and inducing appetite. However, marijuana can also cause damage to your body.

Contrary to popular belief among those who regularly use marijuana, marijuana smoke can, in fact, cause many of the same respiratory problems from which tobacco smokers suffer such as cough, increased phlegm production, more frequent illnesses like bronchitis and pneumonia, and greater instance of lung infections

However, according to a 2013 study by UCLA professor of pulmonary and critical care medicine Dr. Donald Tashkin, heavy marijuana users do not seem to be at a higher risk for developing lung cancer. While this is good news, another study in 2017 did find that regular marijuana users were 26 percent more likely to suffer a stroke—and ten percent more likely to develop heart problems, including increasing heart rate from as little as 20 percent up to 100 percent—than non-smokers. Because marijuana is still illegal under federal law, long-term studies on other aspects—such as edibles—are lacking.

Marijuana also affects both gross and fine motor skills which makes driving or otherwise operating any heavy machinery risky while under the influence.

The effects of marijuana on the brain

Marijuana targets the same brain pleasure centers as cocaine, alcohol, and heroin. Depending on consumption, quality, and quantity, marijuana can produce a feeling of euphoria—a “high”—by stimulating brain cells to release dopamine.

Marijuana can also alter your mood, make you feel more relaxed, stimulate your senses, affect time, and increase appetite. Marijuana can also cause anxiety, short-term memory loss, sedation, elation, relaxation, pain-relief, paranoia, hallucinations, concentration issues, decreased interest, and a host of physical effects such as loss of coordination and tachycardia.

Additionally, when coming down from the high, you may feel quite tired or depressed and, in some cases, may suffer from anxiety, insomnia, irritability, and agitation.

Emerging evidence suggests that marijuana may also affect your memory, learning, and attention for as many as 24 hours after use. There is no evidence suggesting sustained harm in these area with long-term use.