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 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 of Smoking 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

While smoking weed is often associated with decreased anxiety and feelings of relaxation, this is not always the case. 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 of Smoking 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.

Smoking Weed and Addiction

While most people who smoke weed do not become addicted, it is possible to develop a marijuana addiction. Cannabis use disorder (also known as marijuana use disorder), is a distinct condition recognized in the Diagnostic and Statistical Manual of Mental Disorders (DSM-5-TR), the tool clinicians use to diagnose mental health conditions. 

Marijuana addiction is characterized by symptoms that include:

  • The need to use larger amounts to achieve the same effects (tolerance)
  • Continuing to smoke weed despite negative consequences
  • Physical dependence and withdrawal symptoms

According to the National Institute on Drug Abuse (NIDA), around 30% of people who use marijuana will develop an addiction.

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 (THC).
  • Previous experience with the drug: If you use 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.

How to Stop Smoking Weed

If you want to stop smoking weed because you are concerned about its effects on your health or potential for addiction, some strategies can help.

When quitting, there are two different approaches that you might choose.

  • Tapering: First, you might decide to taper your use gradually until you eventually just quit. This approach helps minimize withdrawal symptoms and is recommended by the American Society of Addiction Medicine.
  • Cold turkey: The other method is to quit cold turkey. This approach may be more likely to lead to withdrawal symptoms if you have been smoking weed heavily or for a long time. 

If you have been smoking weed heavily or for a long time, it may take a few weeks to recover from marijuana withdrawal completely. The acute effects of withdrawal usually peak within 48 to 72 hours, but other symptoms—such as insomnia and irritability— may gradually decrease over the next two to three weeks.

You might also opt to talk to your doctor or a mental health professional for assistance. Some clinical trials have found that the prescription medication buspirone, which is used to treat anxiety, can also help reduce drug cravings and minimize some withdrawal 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 smoking or ingesting 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.

14 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.
  1. National Institute on Drug Abuse. Marijuana: Drug facts.

  2. Partnership for Drug-Free Kids. Marijuana.

  3. National Institute on Drug Abuse. What are marijuana's long-term effects on the brain?.

  4. Centers for Disease Control and Prevention. Outbreak of lung injury associated with the use of e-cigarette, or vaping, products.

  5. American Psychiatric Association (APA). Diagnostic and Statistical Manual of Mental Disorders. 5th ed, text revision. Washington, D.C.; 2022.

  6. Hser Y-I, Mooney LJ, Huang D, et al. Reductions in cannabis use are associated with improvements in anxiety, depression, and sleep quality, but not quality of lifeJournal of Substance Abuse Treatment. 2017;81:53-58. doi:10.1016/j.jsat.2017.07.012

  7. Monte AA, Shelton SK, Mills E, et al. Acute illness associated with cannabis use, by route of exposure. Ann Intern Med. 2019;170(8):531-537. doi:10.7326/M18-2809

  8. Herron AJ, Brennan TK. The ASAM Essentials of Addiction Medicine, 2nd Edition; 2015.

  9. Brezing CA, Levin FR. The current state of pharmacological treatments for cannabis use disorder and withdrawalNeuropsychopharmacology. 2018;43(1):173-194. doi:10.1038/npp.2017.212

  10. Mayo Clinic. Medical marijuana.

  11. Substance Abuse and Mental Health Services Administration. National Survey on Drug Use and Health.

  12. American College of Obstetricians and Gynecologists. Committee Opinion No. 722: Marijuana use during pregnancy and lactation. Obstet Gynecol. 2017;130(4):e205-e209. doi:10.1097/aog.0000000000002354

  13. Sorensen CJ, DeSanto K, Borgelt L, Phillips KT, Monte AA. Cannabinoid hyperemesis syndrome: Diagnosis, pathophysiology, and treatment—a systematic review. J Med Toxicol. 2017;13(1):71-87. doi:10.1007/s13181-016-0595-z

  14. National Conference of State Legislatures. State medical cannabis laws.

By Buddy T
Buddy T is an anonymous writer and founding member of the Online Al-Anon Outreach Committee with decades of experience writing about alcoholism.