How Pot Affects Your Mind and Body

Medically Reviewed by Jabeen Begum, MD on January 12, 2024
10 min read

Marijuana, weed, pot, dope, grass. They’re different names for the same drug that comes from the cannabis plant. You can smoke it, vape it, drink it, or eat it. Many people use marijuana for pleasure and to relax. But a growing number of doctors prescribe it for specific medical conditions and symptoms.

Marijuana has mind-altering compounds that affect both your brain and body. It can be addictive, and it may harm some people’s health. Here’s what can happen when you use marijuana:



It’s why most people try marijuana. The main psychoactive ingredient, THC, stimulates the part of your brain that responds to pleasure, like food and sex. That unleashes a chemical called dopamine, which gives you a euphoric, relaxed feeling.

If you vape or smoke weed, the THC could get into your bloodstream quickly enough for you to get your high in seconds or minutes. The THC level usually peaks in about 30 minutes, and its effects may wear off in 1-3 hours. If you drink or eat pot, it may take many hours for you to fully sober up. You may not always know how potent your recreational marijuana might be. That also goes for most medical marijuana.

Not everyone’s experience with marijuana is pleasant. It often can leave you anxious, afraid, panicked, or paranoid. Using marijuana may raise your chances of clinical depression or worsen the symptoms of any mental disorders you already have. Scientists aren’t yet sure exactly why. 

In high doses, it can cause psychosis, which makes you paranoid or causes you to lose understanding of what's real and what's not, so you hear or see things that aren’t there and can have long-lasting odd thoughts. Psychosis lessens as your high comes down.

Increased risk of schizophrenia

Psychosis is a symptom of a serious medical condition called schizophrenia. Schizophrenia also affects the way you understand what's real, but it includes other symptoms like trouble with speech and not being able to focus and show emotions. Also, schizophrenia, unlike psychosis, is long-term. 

Recent research suggests that if you start to use marijuana at a young age, use it frequently, and for a long period of time, you could be at risk of having schizophrenia or other mental conditions that involve psychosis. This risk could be higher in young men or people assigned male at birth, especially those 16 to 25 years of age. 

Studies also note that if you're at risk of a mental condition, you may be more likely to smoke marijuana at an earlier age, maybe as a way to medicate yourself. 

Once you have schizophrenia, stopping marijuana use won't make the condition or its symptoms go away.

If you think you're addicted to marijuana, getting an early diagnosis can help with treatment and prevent the risk of chronic conditions like schizophrenia.

Marijuana can cloud your senses and judgment. The effects can differ, depending on things like how potent your marijuana was, how you took it, and how much marijuana you’ve used in the past. It might:

  • Make your senses stronger (colors might seem brighter and sounds might seem louder)
  • Twist your sense of time
  • Hurt your motor skills, or skills that involve our muscles completing certain actions, and make driving more dangerous
  • Lower your inhibitions so you may have unsafe sex or take other chances

About 1 in 10 people who use marijuana will become addicted, or have cannabis use disorder. This means you can’t stop using it even if it harms your relationships, school, job, health, or finances. The CDC states that you have a 10% risk of a cannabis use disorder if you use marijuana.

Like the possible risk of chronic conditions like schizophrenia, the chances of cannabis use disorder are greater the younger you start marijuana and the more heavily you use it. For instance, the odds of addiction are 1 in 6 if you use marijuana in your teens. It might be as high as 1 in 2 among those who use it every day.

You might have cannabis use disorder if you:

  • Crave weed
  • Try to quit cannabis but fail
  • Spend a lot of your time using cannabis
  • Use more marijuana than you had planned to
  • Miss out on time with family or friends to use pot
  • Still use marijuana even though it causes you physical or mental problems
  • Use pot while you drive or during other high-risk activities
  • Need more weed to get the same high
  • Have issues with learning, attention, or memory

You could also grow physically dependent on marijuana. Your body could go into withdrawal, leaving you cranky, restless, unable to sleep, and uninterested in eating when you don’t use it.

If you need surgery and use cannabis, make sure to tell your doctor about your use. Whether you use it recreationally or medically, it can affect how your anesthesia works. If your doctor is aware of your use, they'll be able to take the steps to make sure you stay sedated, or "asleep," for the entire surgery. People who use marijuana at least once a week, called chronic users, might need more anesthesia than others.

The American Society of Regional Anesthesia and Pain Medicine issued guidelines in 2023 for information to share with your doctors before any surgery. They include sharing:

  • Whether you use pot
  • How often you use it
  • How much you use
  • What type of pot you use
  • How recently you used it

If you used it recently, your doctor might reschedule your surgery if it's elective and not an emergency. This is the case even if you don't use pot a lot.

If you tell your doctor about your pot use, it's then part of your medical record. But that's private information. Your doctor won't judge you for it. Their job is to help you get the best outcome possible.

If you don't tell them, your doctor may figure it out anyway after you're asleep for surgery. That's because your body will show signs: Your level of consciousness and the amount of medication you need may let them know. It can take 10 times the amount of medication to keep you asleep if you use cannabis regularly, compared to those who don't use it.

But it's best that you tell your medical team so they can give you the best care. 

Extra risks involved with surgery when you use pot include:

Your stomach contents coming into your throat. People who have recently used or chronically use marijuana might take longer to empty their stomachs. Because of this, if you use pot, you're at risk of your stomach contents coming back up into your throat and being sucked into your lungs before your anesthesiologist is able to put in your breathing tube.

Having a heart attack. If you already have heart disease, your risk of a heart attack goes up even more if you use marijuana within 60 minutes of getting anesthesia. Tell your doctor if you use pot so they can keep an eye on your risk.

Added health problems if you need more anesthesia. If you need more anesthesia to fall asleep because of your pot use, you're at a higher risk of low blood pressure and a delayed wake-up after surgery.

Breathing issues. If you smoke pot regularly, it can lead to coughing, wheezing, phlegm, and a higher risk of respiratory infections. This may cause issues when you get anesthesia. Your airways may be more sensitive, which could cause problems when your doctor puts in or takes out your breathing tube. Along with having trouble breathing, you might feel like you're having an asthma attack or have less oxygen in your lungs.

Complications after surgery. Chronic pot users tend to have more pain after surgery. This could cause you to rely more on opioids to ease the pain. If you use these drugs more, you're at risk for opioid use disorder.

No matter how often you use pot, avoid it on the day of planned surgery. If you don't, or your surgery is unplanned, you risk life-threatening complications:

  • If you use cannabis on the day of surgery, it can increase your heart rate and lower your blood pressure. This can lead to a heart attack.
  • If you take edibles on the day of your procedure, it could cause aspiration pneumonia, which happens if you inhale food into your lungs. This can be fatal.

Marijuana can make it harder for you to focus, learn, and remember things. This seems to be a short-term effect that lasts for 24 hours or longer after you stop smoking.

Studies note that early marijuana use can interrupt normal development of gray matter, a type of brain tissue that helps control mental functions, increasing schizophrenia risks. Early exposure to marijuana is also linked to changes in areas of the brain that are often connected with psychosis.

Using pot heavily, especially in your teen years, may leave more permanent effects. Imaging tests with some – but not all – adolescents found that marijuana may physically change their brains. Specifically, they had fewer connections in parts of the brain linked to alertness, learning, and memory, and tests show lower IQ scores in some people.


Marijuana smoke can inflame and irritate your lungs. If you use it regularly, you could have the same breathing problems as someone who smokes cigarettes. That could mean ongoing coughing with colored mucus. Your lungs may more easily pick up infections. That’s partly because THC seems to weaken some users’ immune systems.

Medical marijuana is legal in some form in a majority of states. And 25 states and Washington, DC, have legalized recreational marijuana. But the federal government’s ban on marijuana has made it hard to study its effects on humans. Limited research shows that medicinal pot might help:

  • Ongoing pain (This is the most common use and a possible benefit of medical marijuana.)
  • Stiff muscles or muscle spasms from multiple sclerosis
  • Sleep problems for those with fibromyalgia, MS, and sleep apnea
  • Anxiety
  • Loss of appetite and weight loss in people with AIDS
  • Nausea or throwing up from chemotherapy
  • Seizures from epilepsy
  • Dravet syndrome or Lennox-Gastaut syndrome

Many people who use marijuana regularly notice that it boosts their appetite. They call this “the munchies.” Some research suggests that might help people with AIDS, cancer, or other illnesses regain weight. Scientists are studying this and whether it’s safe.

Marijuana makes your heart work harder. Normally the heart beats about 50 to 70 times a minute. But that can jump to 70 to 120 beats or more per minute for 3 hours after the effects kick in. The added strain plus tar and other chemicals in pot may raise your chance of having a heart attack or stroke. The danger is even greater if you’re older or if you already have heart problems.

More than 1 in 10 drinkers say they have used marijuana in the past year. Combining alcohol and marijuana at the same time roughly doubled the odds of drunk driving or legal, professional, or personal problems, compared to drinking alone.

Mothers who smoke pot while pregnant face a higher risk of giving birth to underweight or premature babies. But researchers don’t know enough to say if those infants are more likely to grow up to struggle in school, use drugs, or have other problems in life.

Researchers haven’t found any links between smoking marijuana and cancers in the lung, head, or the neck. Limited evidence suggests that heavy marijuana use may lead to one type of testicular cancer. We don’t have enough information on whether cannabis may lead to other cancers, including:

  • Prostate
  • Cervical
  • Bladder
  • Non-Hodgkin's lymphoma

You can use marijuana in a variety of ways. Smoking usually offers the quickest way to feel its effects:

  • Rolled cigarettes
  • Small handheld pipes
  • A water pipe, called a bong
  • A cigar that has been hollowed out and refilled with marijuana, called a blunt
  • Sticky resins drawn from the cannabis plant. Resins often are loaded with much higher amounts of THC than regular marijuana

You also can mix it into brownies, cookies, candy, tea, and other foods. Eating or drinking the drug delays the high because it has to travel through your digestive system before the THC gets into your bloodstream. So it may take 30 minutes to 2 hours before you feel anything. But edibles give you a high that lasts much longer – up to 8 hours – than if you smoke or vape weed.

It’s short for cannabidiol, a substance found in both marijuana and hemp plants. It doesn’t make you high. CBD can be made into CBD oil and sold as pills, gels, creams, and other formulas. Some people use CBD to treat pain, seizures, and other health problems. But scientists aren’t yet sure how well it works or if it’s safe over the long term. Lack of regulation means you can’t always know exactly what you’re buying.

Marijuana can be used in a variety of ways and for many reasons. More research about the short-term and long-term effects of marijuana is needed. If you think you may be addicted to marijuana, talk to your doctor about your symptoms. Treatment works best when conditions that may be linked to marijuana use are discovered early.