Cannabis-based products come from the dried flowering tops, leaves, stems, and seeds of the Cannabis sativa (hemp) plant.

The legal status of medical and recreational cannabis varies among states. People who are considering buying or using cannabis should first check whether it is legal in their state.

What is cannabis?

Cannabis is a plant. People use the dried leaves, seed oil, and other parts of the cannabis plant for recreational and medicinal purposes. It can have a pleasurable effect and may soothe the symptoms of various conditions, such as chronic pain.

Ways of using it include:

  • smoking or vaping it
  • brewing it as a tea
  • consuming it in the form of edibles, such as brownies or candies
  • eating it raw
  • applying it as a topical treatment
  • taking it as capsules or supplements

Some of the ingredients in cannabis are psychoactive (mind-altering), but others are not. The potency and balance of the ingredients vary, depending on how the manufacturer grows and processes the plant.

What are CBD and THC?

Cannabis contains at least 120Trusted Source active ingredients, or cannabinoids. The most abundant ones are cannabidiol (CBD) and delta-9-tetrahydrocannabinol (THC).

Some cannabinoids can have euphoric or psychoactive effects. THC produces both effects.

CBD is present in various forms, including:

  • oils for applying to the skin
  • capsules, to take as a supplement
  • gummy candies

So far, most studies have focused on CBD and THC, but scientists are looking into the effects of other cannabinoids, too.

Is CBD legal? Hemp-derived CBD products with less than 0.3% THC are legal federally but still illegal under some state laws. Cannabis-derived CBD products, on the other hand, are illegal federally but legal under some state laws. Check local legislation, especially when traveling. Also, keep in mind that the Food and Drug Administration (FDA) has not approved nonprescription CBD products, which may be inaccurately labeled.

Medical uses

According to the National Academies of Sciences, Engineering, and Medicine, there is conclusive evidence that cannabis or cannabinoids can help manage:

  • chronic pain in adults
  • nausea and vomiting resulting from chemotherapy treatment
  • some symptoms of multiple sclerosis (MS)

There is moderate evidence that it can help with sleep problems relating to sleep apnea, fibromyalgia, chronic pain, and MS.

Other conditions that it may be helpful for include:

  • low appetite
  • Tourette’s syndrome
  • anxiety, in some individuals

In 2018, the Food and Drug Administration (FDA)Trusted Source approved Epidiolex, a medication that derives from cannabis, to treat two rare and severe types of epilepsy that do not respond well to other treatments. Epidiolex is a purified form of CBD that does not contain THC.

Three drugs that contain synthetic substances with a structure similar to that of THC have received FDA approval. Marinol, Syndros, and Cesamet are treatment options for some kinds of anorexia.

How do cannabinoids work?

The human body naturally produces some cannabinoids through the endocannabinoid system. They act in a similar way to neurotransmitters, sending messages throughout the nervous system.

These neurotransmitters affect brain areas that play a role in memory, thinking, concentration, movement, coordination, sensory and time perception, and pleasure.

The receptors that respond to these cannabinoids also react to THC and other cannabinoids. In this way, cannabinoids from an outside source can change and disrupt normal brain function.

THC appears to affect areas of the brain that control:

Due to these effects, a person should not drive a car, operate heavy machinery, or engage in risky physical activities after using cannabis.

THC stimulates specific cannabinoid receptors that increase the release of dopamine. Dopamine is a neurotransmitter that relates to feelings of pleasure.

THC can also affect sensory perception. Colors may seem brighter, music more vivid, and emotions more profound.

Do the benefits of cannabis outweigh the risks? Find out here.

What does a person feel?

When people use cannabis, they may notice the following effects:

  • a feeling of elation or euphoria, known as a high
  • relaxation
  • changes in perception, for example, of color, time, and space
  • an increase in appetite
  • feeling more talkative

Learn more about how cannabis affects the body.


Using cannabis can also entail some risks. These include:

  • Impairment of judgment: A 2012 studyTrusted Source reported a higher chance of having a road traffic accident when driving within 3 hours of smoking cannabis.
  • Immune response: A 2019 study showed that frequent cannabis use may affect the immune system, but more studies are necessary to confirm this.
  • Gum disease: According to the American Dental Association, there may be a link between cannabis use and gum disease
  • Memory loss: One studyTrusted Source found that smokers of potent cannabis strains (skunk, for instance) may have a higher risk of acute memory loss.
  • Testicular cancer: A 2018 reviewTrusted Source concluded that using cannabis more than 50 times in a lifetime may increase the risk of testicular cancer.

People have modified some types of cannabis, such as skunk, to maximize the potency of certain components. From the 1990s to 2018, the average THC content in confiscated cannabis rose from 4% to over 15%.

One problem with using unregulated or recreational drugs is that people cannot know exactly what they contain or how strong the effect will be. There may also be contaminants.

Can cannabis use kill you? Find out here.


With long-term use, changes in the brain can occur that lead to problematic use, or cannabis use disorder. This disorder, in which a person experiences withdrawal symptoms when not taking the drug, may affect about 30% of people who use cannabis, according to the National Institute on Drug Abuse (NIDA).

Of these individuals, about 9% may develop an addiction. A person has an addiction when they cannot stop using a substance.

The NIDA add that up to 17% of those who start using cannabis in their teens may become dependent on it.

Cannabis withdrawal

Quitting cannabis, after becoming dependent, is not life threatening, but it can be uncomfortable.

Symptoms may include:

  • irritability
  • mood changes
  • insomnia
  • cravings
  • restlessness
  • decreased appetite
  • general discomfort

Symptoms tend to peak within the first week after stopping and last up to 2 weeks.

Experts do not know exactly how frequent and long-term cannabis use affects a person’s health. Both the short- and long-term effects may vary among individuals.


Cannabis contains chemicals that can have various effects on the human body. It is a popular recreational drug with some medicinal uses.

Anyone who is considering using cannabis for any purpose should first check that it is legal to use in their state. They should also consider its possible effects on their mental and physical health.

A doctor can be a good person to ask for advice.

Last medically reviewed on June 30, 2020

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