What Happens When You Smoke Weed?

man smoking a joint

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What can happen to you when you smoke weed depends on a lot of factors, and can vary from person to person. In addition to the immediate short-term impact of weed (also known as pot, marijuana or cannabis), long-term effects on both your mind and body are possible.

Different ways of using cannabis can also play a role in how it impacts your body. Smoking marijuana is one of the fastest routes of administration, so it produces rapid changes in your brain and body. To understand the possible risks of marijuana, it is important to first understand what happens to your body when you smoke weed.

Short-Term Effects When You Smoke Weed

Reactions to using marijuana can vary dramatically, from person to person and from day to day. Some people report not feeling anything at all when they smoke marijuana. In other cases, people report feeling relaxed or "high."

Short-Term Effects on the Body

The effects of using marijuana can be unpredictable, especially when it is mixed with tobacco, alcohol, or other drugs. You may feel relaxed when you smoke weed, but you also may experience unexpected and unpleasant symptoms, such as:

  • Accelerated heart rate
  • Bloodshot eyes
  • Dry mouth
  • Loss of coordination
  • Swollen eyelids

Short-Term Effects on the Mind

As with any drug or substance that can alter perception, logic, and usual behavior, there are several short-term hazards of using marijuana. These include:

  • Anxiety and paranoia
  • Difficulty in thinking
  • Impaired memory
  • Lack of attention and focus
  • Learning difficulties
  • Poor driving skills

Some people who use marijuana report having sudden feelings of anxiety and paranoid thoughts. This might be caused by using higher-potency marijuana, deliberately or inadvertently.

Research also shows that regular use of marijuana is linked to an increased risk of depression, anxiety, and a loss of motivation or drive. You may feel "dopey" on the drug, which is when you begin to lose interest in activities that you might have previously enjoyed, and/or lose the ability to grasp concepts easily.

Long-Term Effects When You Smoke Weed

Any drug that is taken over a prolonged period of time can have an effect on your health. Physical changes resulting from persistent use of marijuana can range from infertility to issues with brain function.

  • Increased risk of lung, head, and neck cancers
  • Decreased sperm count
  • Heightened risk of infections, especially in the lungs
  • Inability to shift attention normally
  • Inability to understand complex information​
  • Irregular menstruation
  • Lack of motivation
  • Poor short-term memory recall
  • Respiratory problems

Some studies suggest that the impact that marijuana has can depend on the age at which a person began smoking marijuana and for how long they used the substance. People who use marijuana in adolescence and continue using for a long time may experience more significant effects.

Smoking vs. Vaping

In addition to smoking and being consumed in edibles, marijuana can also be inhaled by vaping heated oil through an e-cigarette. There is little known about the negative health effects of vaping THC products, but a number of serious lung injuries have been attributed to vaping. The CDC recommends avoiding vaping products containing THC, the psychoactive chemical in marijuana.

Why Reactions to Weed Differ

The National Institute on Drug Abuse reports that marijuana can affect each person differently according to their own body chemistry and the type of pot used. Some people can use weed and never have any negative reactions, while others may find the experience very unpleasant and unsettling.

Factors that influence how you might respond when you smoke weed include:

  • Marijuana strength (amount of active ingredient THC): Studies have found that the marijuana available today is much different in terms of potency compared to what was generally available in the 1960s when the use of the drug became widespread in the United States. Today's strains of the plant contain much more of the active ingredient in marijuana, tetrahydrocannabinol or THC.
  • Previous experience with the drug: If you have used marijuana regularly, it may mean that you have developed a tolerance to the substance. This means that it requires more of the drug to produce the same effects that you initially felt.
  • How it's taken: Smoking marijuana produces rapid effects because the substance begins to affect the brain quickly. When ingested, it takes longer to have an effect.
  • Whether alcohol or other drugs are taken too​: Taking other substances can have an effect on how marijuana impacts your mind and body. Tobacco, alcohol, and other drugs can interact with marijuana to heighten the adverse effects of both substances.
  • Your biology (genetic makeup): Genetics as well as other biological factors can affect how a person responds to and metabolizes a substance. Age, hydration levels, body mass, metabolism, sex, and frequency of use may all play a role. For example, women tend to metabolize THC at a somewhat slower rate than men, which may impact how the drug affects them.

Effects of Edibles

As recreational marijuana becomes legal in more states in the U.S., more edible products containing marijuana are available for sale. When marijuana is ingested, it is absorbed by the body more slowly and the effects can last longer and be stronger, or be unpredictable.

Some research has shown that there are more emergency department visits related to edible marijuana than expected. In one study, visits related to edibles were more likely than those related to inhaled marijuana to involve acute psychiatric symptoms, intoxication, and cardiovascular symptoms.

A Word From Verywell

Marijuana has a reputation for being harmless and non-addictive. But when you smoke weed, it does affect your body and brain—sometimes in serious or surprising ways. It's important to be aware of these risks when choosing to smoke or ingest cannabis.

Frequently Asked Questions

  • Why do people smoke weed?

    People may smoke weed recreationally for a variety of reasons, such as to relieve stress, escape uncomfortable situations or feelings, or to self-treat a mental health condition. They may smoke in social settings or with a partner.
    Cannabis used to treat symptoms of a medical condition is sometimes smoked. Or it may be in pill, liquid, oil, or powder form and be consumed orally.

  • How many people smoke weed?

    In 2020, about 18% of Americans age 12 and older reported using marijuana, according to survey data from the U.S. Substance Abuse and Mental Health Services Administration (SAMHSA). That's about 49.6 million people. The survey doesn't specify what proportion of marijuana use was from smoking.

  • What happens if you smoke weed while pregnant?

    Smoking weed during pregnancy may be harmful to a developing baby and may increase the risk of complications such as miscarriage, preterm birth, and stillbirth, especially in people who smoke frequently or who also smoke tobacco. Babies exposed to marijuana in utero may have learning and behavior problems in early childhood. The American College of Obstetricians and Gynecologists recommends avoiding marijuana during pregnancy.

  • What happens if you smoke too much weed?

    Smoking too much weed at one time may cause anxiety, paranoia, impaired thinking, and impaired driving skills. Smoking weed chronically (frequently, over long periods of time) can mean an increased risk of cancer and infections, problems with brain development and function, and infertility and pregnancy complications. Frequent (weekly or more) cannabis use can cause cannabinoid hyperemesis syndrome—repeated bouts of severe nausea and vomiting.

  • Where is it legal to smoke weed?

    Nonmedical, or recreational, marijuana is legal in 18 U.S. states and the District of Columbia (as of February 2022): Alaska, Arizona, California, Colorado, Connecticut, Illinois, Maine, Massachusetts, Michigan, Montana, Nevada, New Jersey, New Mexico, New York, Oregon, Vermont, Virginia, and Washington.

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10 Sources
Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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