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“They had much worse cardiovascular effects, much worse agitation,” he says. The two products are chemically different, he explains, and so their safety should be considered separately. “The safety of marijuana has been borne out over decades. This is a whole new world.”

Scientific evidence also links long-term marijuana smoking with chronic bronchitis and respiratory symptoms like coughing and wheezing (there is not an established association between smoking weed and the incidence of lung or head and neck cancer). The long-term health effects of vaping remain mostly unknown.

In one 2014 study, a group of French researchers examined 35 medical cases and concluded that cannabis could be a potential trigger for cardiovascular complications in young people. And when researchers from the Einstein Medical Center in Philadelphia analyzed a national database of patients, they found the prevalence of heart failure, stroke, coronary artery disease, and sudden cardiac death, were significantly higher in patients with cannabis use, according to results published in 2018. After adjusting for a number of factors including age, sex, diabetes, and tobacco or alcohol use, they found cannabis use remained an independent predictor of both heart failure and stroke.

“That could [be a] potentially life-threatening situation for a child,” says Mount Sinai’s Manini. “Children are not little adults”—their bodies process all drugs differently than even a more petite adult would.

According to the National Institute on Drug Abuse (NIDA), a government agency that handles drug use and addiction, there has yet to be an adult death attributable solely to marijuana. The Centers for Disease Control and Prevention also states that while using too much marijuana can cause extreme confusion, emotional distress, increased blood pressure, heart rate, severe nausea, or unintentional injury, “a fatal overdose is unlikely.”

Marijuana is still a Schedule I drug, according to the federal government, and technically still doesn’t have any currently accepted medical uses. Still, numerous states have moved to legalize marijuana for recreational or medical treatment (mostly for conditions such as cancer, HIV/AIDS, multiple sclerosis, glaucoma, seizures, epilepsy, and chronic pain). We also know—from a 2016 analysis of marijuana samples from materials confiscated by the Drug Enforcement Administration over two decades—that the potency of THC in marijuana has increased at least threefold since 1995.

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Cannabis ruderalis is another species that was first discovered in southern Russia. C. ruderalis grows shorter than the other two species of weed and has thin, fibrous stems with large leaves. It is also an autoflowering plant, meaning that it will flower depending on the age of the plant rather than the light conditions.

C. indica produces large amounts of THC and low levels of CBD and, therefore, it is considered a strong weed. It tends to be very relaxing or sedating, sometimes making people who consume it want to just hang out on the couch. For this reason, it is commonly used at night before going to bed. It creates more of a “body high” due to its relaxing effects.

Because of its sedative effects, indica is often used by people who experience insomnia. A recent study showed that more people found relief from insomnia and pain when using the indica strain , compared to sativa . This effect may be a result of the higher levels of THC.


Its name comes from the fact that the origin of the strain is unknown, making it like a dream. It has a sweet taste that some describe as similar to blueberries and sugar.

The main active ingredient in weed is the chemical Δ-9- tetrahydrocannabinol, or THC. THC has psychoactive effects, meaning that it can alter mood, alertness, cognizance and cognitive functioning. Cannabidiol or CBD is also a large component of weed plants and has relaxation effects but does not have the psychoactive effects of THC. CBD is also thought to relieve pain.

The following are a few of the common or coveted strains of weed and the effects they are known to have:

New types of weed sometimes have interesting names , which are usually based on their effects, origin, or the way they appear or smell. Some examples include: Purple Urkle, Willy’s Wonder, Permafrost, Pineapple Express, Strawberry Cough and Island Sweet Skunk.

before the 12th century, in the meaning defined at intransitive sense

Definition of weed (Entry 3 of 3)

before the 12th century, in the meaning defined at sense 1a(1)

First Known Use of weed

Middle English, from Old English wēod weed, herb; akin to Old Saxon wiod weed

Definition of weed (Entry 2 of 3)

before the 12th century, in the meaning defined at sense 1

Middle English wede, from Old English wǣd, gewǣde; akin to Old Norse vāth cloth, clothing and perhaps to Lithuanian austi to weave