What Type of Drug is Cannabis?

Cannabis is the generic term for the psychoactive drug that is also known as marijuana, dope, weed and many other names. The technical name of the cannabis plant is cannabis sativa.

According to this UN report, cannabis was the world’s most widely produced, trafficked, and consumed drug in 2010. Between 119 million and 224 million adults around the world used the drug that year.

How Does Cannabis Work?

The main psychoactive (mind-altering) chemical in cannabis is called delta-9 tetrahydro-cannabinol, commonly known as THC. This is the part of the plant that gives the “high.” There is a wide range of THC potency between cannabis products, and THC content in illegally supplied cannabis has increased massively over the last 50 years.

Cannabis is used in three main forms: marijuana, hashish and hash oil. Marijuana is generally made from the dried flowers and leaves of the cannabis plant. It is the least potent of all the cannabis products and is usually smoked. Hashish is made from the resin (a secreted gum) of the cannabis plant. It is dried, pressed into small blocks and smoked. It can also be added to food and eaten. Hash oil, the most potent cannabis product, is a thick oil obtained from hashish. Cannabis is generally smoked but it can also be ingested and can be added to cakes (“hash cookies”).

Cannabis is also known as marijuana, grass, pot, dope, Mary Jane, hooch, weed, hash, brew, cones, smoke, mull, buddha, ganja, hydro, yarndi, heads, shit and green. The cigarettes in which cannabis are smoked are usually called joints or reefers.


When cannabis is smoked, THC rapidly passes from the lungs into the bloodstream and then to the brain and other organs throughout the body. It is absorbed more slowly when ingested in food or drink.

When cannabis is consumed for recreational purposes, the following effects are possible:

  • A change in perception. It can have hallucinogenic effects, making users see reality in a distorted way.

  • Alteration in mood. Some people who use cannabis do so to experience a sense of euphoria, while others experience a state of relaxation, often referred to as a “high”.

  • Palpitations

  • Impairment of working memory

  • Impairment of short-term memory
  • Impairment of concentration

  • More rapid breathing

  • Talkativeness

  • Drowsiness

  • Loss of inhibitions

  • Decreased nausea

  • Increased appetite

  • Loss of co-ordination

  • Anxiety and paranoia

  • Dryness of the eyes, mouth, and throat

  • Increased appetite and craving for sweets

  • Difficulty paying attention

Signs of Cannabis Abuse

  • Bursts of laughter in the early stages of intoxication

  • Drowsiness

  • Lack of concentration and coordination

  • Forgetfulness

  • Bloodshot eyes

  • Distorted sense of time

  • Possession of paraphernalia, including packs of rolling papers, pipes or “bongs”

  • Paranoia and delusional behaviour

Health Risks

Research has shown that, in chronic users, cannabis has an adverse impact on learning and memory abilities, which persists long after the effects of the drug wear off. When cannabis use begins in adolescence the effects may persist for many years, and the damage done to the growing brain are generally greater.

Cannabis use has been linked in a few recent studies to an increased risk of respiratory diseases associated with smoking, including lung cancer, as well as decreased libido and fertility and an aggressive type of testicular cancer in young men.

High doses of cannabis can cause psychosis or panic. Some people experience an acute psychotic reaction (disturbed perceptions and thoughts, paranoia) or panic attacks while under the influence of cannabis.

There is a strong link between cannabis use starting before the age of 16 and schizophrenia in late life. Cannabis use can also worsen psychotic symptoms in people who already have schizophrenia.

According to different studies and reports, cannabis consumption can also result in:

  • Acute memory loss.

  • Depression.

  • Weakening the body’s immune system.

  • Severe vomiting sickness.

  • Paranoia.

Withdrawal Symptoms

Long-term cannabis users trying to quit report withdrawal symptoms such as irritability, aggression, insomnia, night sweats, loss of appetite, weight loss (or weight gain), digestion problems, cramps or nausea after eating, restlessness, anxiety, depression and craving — all of which can makes it difficult to remain abstinent.

Treatment for Cannabis Addiction

Behavioural interventions, including cognitive-behavioural therapy, family therapy and motivational incentives are proven to be effective in treating cannabis addiction.

Read about the treatment of cannabis addiction at Castle Craig Hospital in Scotland, in our Treatment section.


Page last reviewed and medically fact-checked | September 28, 2020