What is Cannabis?

What is Cannabis?

Cannabis is derived from the cannabis plant (cannabis sativa). It grows wild in many of the tropical and temperate areas of the world. It can be grown in almost any climate, and is increasingly cultivated by means of indoor hydroponic technology.

The main active ingredient 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.

Cannabis is used in three main forms: marijuana, hashish and hash oil. Marijuana is made from dried flowers and leaves of the cannabis plant. It is the least potent of all the cannabis products and is usually smoked or made into edible products like cookies or brownies (see Factsheet: Marijuana Edibles). Hashish is made from the resin (a secreted gum) of the cannabis plant. It is dried and 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. It is also smoked.

Cannabis is usually smoked in hand-rolled cigarettes (known as "joints") or in special waterpipes ("bongs"). These pipes or bongs can be bought or made from things such as orange juice containers, soft drink cans or even toilet rolls.

How Many People Use Cannabis?

Cannabis is the most widely used illicit drug in the United States. According to the 2012 National Survey on Drug Use and Health, 7.3% of Americans aged 12 or older had used marijuana within the previous 30 days. The average age at first use was 17.9 years.

Though use of marijuana among Washington state youth has remained relatively stable over the last several years (see Healthy Youth Survey), youth perception of harm from use of marijuana has been steadily decreasing (meaning: fewer adolescents believe marijuana use is harmful). Marijuana is the second most-commonly used substance among 12th graders (alcohol is the first), with 27% of high school seniors reporting current (past 30-day) use.

Other Names for Cannabis

Cannabis is also known as marijuana, grass, pot, dope, Mary Jane, hooch, weed, hash, joints, brew, reefers, cones, smoke, mull, buddha, ganga, hydro, yarndi, heads and green.

What Are the Short-Term Effects of Cannabis?

The short-term effects of using cannabis may include:

  • Feeling of well-being

  • Talkativeness

  • Drowsiness

  • Loss of inhibitions

  • Decreased nausea

  • Increased appetite

  • Loss of co-ordination

  • Bloodshot eyes

  • Dryness of the eyes, mouth, and throat

  • Anxiety and paranoia

What Are the Long-Term Effects of Cannabis?

There is limited research on the long-term effects of cannabis. On the available evidence, the major probable adverse effects are:

  • Increased risk of respiratory diseases associated with smoking, including cancer

  • Decreased memory and learning abilities

  • Decreased motivation in areas such as study, work or concentration


Most people who use cannabis do so to experience a sense of mild euphoria and relaxation, often referred to as a "high." Cannabis causes changes in the user's mood and also affects how they think and perceive the environment, e.g. everyday activities such as watching the television and listening to music can become altered and more intense.

Are there short-term dangers of smoking marijuana?

Discomforts associated with smoking marijuana include dry mouth, dry eyes, increased heart rate and visible signs of intoxication such as bloodshot eyes and puffy eyelids. Other problems may include:

  • Impaired memory and ability to learn

  • Difficulty thinking and problem solving

  • Anxiety attacks or feelings of paranoia

  • Impaired muscle coordination and judgment

  • Increased susceptibility to infections

  • Dangerous impairment of driving skills. Studies show that it impairs braking time, attention to traffic signals and other driving behaviors.

  • Cardiac problems for people with heart disease or high blood pressure, because marijuana increases the heart rate

  • It is very rare to overdose from marijuana, which sets it apart from most drugs. Higher concentrates increases risk.

Are there long-term consequences to smoking marijuana?

Respiratory problems

Someone who smokes marijuana regularly can have many of the same respiratory problems as cigarette smokers. Persistent coughing, symptoms of bronchitis and more frequent chest colds are possible symptoms. There are over 400 chemicals that have been found in marijuana smoke. Benzyprene, a known human carcinogen, is present in marijuana smoke. Regardless of the THC content, the amount of tar inhaled by marijuana smokers and the level of carbon monoxide are 3 to 5 times higher than in cigarette smoke. This is most likely due to inhaling marijuana more deeply, holding the smoke in the lungs and because marijuana smoke is unfiltered.

Memory and learning

Recent research shows that regular marijuana use can compromise the ability to learn and to remember information by impairing the ability to focus, sustain, and shift attention. One study also found that long-term use reduces the ability to organize and integrate complex information.

In addition, marijuana impairs short-term memory and decreases motivation to accomplish tasks, even after the high is over. In one study, even small doses impaired the ability to recall words from a list seen 20 minutes earlier.


Long-term marijuana use suppresses the production of hormones that help regulate the reproductive system. This can cause decreased sperm counts, possible erectile dysfunction (heavy users) and irregular periods (heavy users). These problems would most likely result in a decreased ability to conceive but not lead to complete infertility.

Is marijuana addictive?

No one would argue that marijuana is as addictive as alcohol or cocaine. However, it's wrong to say that it is not at all addictive. More and more studies are finding that marijuana has addictive properties. Both animal and human studies show physical and psychological withdrawal symptoms from marijuana, including irritability, restlessness, insomnia, nausea and intense dreams. Tolerance to marijuana also builds up rapidly. Heavy users need 8 times higher doses to get the same effects as infrequent users.

For a small percentage of people who use it, marijuana can be highly addictive. It is estimated that 10% to 14% of users will become heavily dependent. More than 120,000 people in the US seek treatment for marijuana addiction every year. Because the consequences of marijuana use can be subtle and insidious, it is more difficult to recognize signs of addiction. Cultural and societal beliefs that marijuana cannot be addictive make it less likely for people to seek help or to get support for quitting.

How do I recognize a problem with marijuana?

Some warning signs are:

  • More frequent use

  • Needing more and more to get the same effect

  • Spending time thinking about using marijuana

  • Spending more money than you have on it

  • Missing class or failing to finish assignments because of marijuana

  • Making new friends who do it and neglecting old friends who don't

  • Finding it's hard to be happy without it

Because THC is fat soluble and remains in the body for up to 3 weeks, it's important to remember that withdrawal symptoms might not be felt immediately. If you find that you can't stop using marijuana, then remember, there's help on campus.

Is marijuana illegal?

In November 2016, California passed Proposition 64, the Adult Use Marijuana Act (AUMA), legalizing recreational marijuana use for adults 21 years of age or older. On January 1, 2018, California began its first day of adult-use cannabis sales, making recreational dispensaries officially open to the public. For more detailed information regarding CA state law click here.

However, the unlawful manufacture, distribution, dispensing, possession, use, or sale of, or the attempted manufacture, distribution, dispensing, or sale of marijuana (medicinal marijuana is not allowed, nor is it a defense to a violation of any University policy or campus rule) is illegal on campus. See the UCSC University Policy on Drugs in the Student Handbook.

What about the medical use of marijuana?

Under the California Medical Marijuana law there are several qualifying conditions that allow users to use marijuana medically. However, at UCSC medical marijuana is not allowed, nor is it a defense to a violation of any University policy or campus rule.

How do I help a friend who's having trouble with drugs?

If you are concerned about a friend's drug or alcohol use, this website contains information about different ways to help them.