There are many effects of marijuana that can have both short- and long-term implications. Beyond the short-term effects of experiencing a “high,” it’s important to consider the long-term consequences of marijuana abuse.

Marijuana, also commonly referred to as cannabis, THC, and weed, is a mind-altering drug that has several effects on the human body and mind. Short-term effects of using marijuana just one time can cause noticeable symptoms to appear. The longer a person uses it, the greater the risk for it to cause larger social changes in their life.

If you’re worried a friend or family member may be struggling with marijuana abuse or addiction, look for a combination of these signs, symptoms and side effects. Although they may try to hide their habit, these symptoms and signs are classic tells of marijuana use.

Article at a Glance:

  • Marijuana can be habit-forming and has many effects on the mind and body.
  • Signs of marijuana abuse are reduced mental and physical abilities, difficulties with work or school, social changes and troubles money or the law.
  • Both physical and psychological symptoms can occur even after only using marijuana one time.
  • Some long-term effects are chronic coughing, a drop in IQ, respiratory infections, mental health issues and addiction.
  • Although there have been no documented fatal marijuana overdoses, nonfatal symptoms of an overdose include extreme paranoia, anxiety, hallucinations and anxiety.

Signs of Marijuana Addiction

As a person becomes more entrenched in marijuana use, you may start to notice a change in their priorities, behavior and social activity. This is because the feeling of getting high on marijuana seems enjoyable, so the person may prioritize getting high over other activities they were previously dedicated to.

Using marijuana (and ingesting THC) causes changes in the brain that may lead to additional changes in a person’s abilities and behavior over time. Some signs of marijuana abuse include:

  • Social changes
  • Employment or academic struggles
  • Reduced cognitive and physical abilities
  • Legal troubles
  • Financial concerns

Social changes, for example, may include a disinterest in former hobbies or friends, partaking in risky behaviors, and a newfound interest in marijuana counterculture. For example, modern cannabis counterculture has an equally strong tie to the Rastafarian lifestyle; images of the marijuana leaf and Bob Marley are both commonly associated with marijuana counterculture.

Marijuana users may also engage in risky behavior. THC affects the frontal cortex, the part of the brain involved in decision-making, which may cause a person to make poor decisions. As a result, a person may choose to drive a car while impaired or have unprotected sex while high. By impairing one’s judgment, marijuana abuse can lead to an increased risk of contracting sexually-transmitted diseases like HIV and AIDS.

Similar to how it affects judgment, THC may also affect a person’s physical abilities. A lack of coordination while high can cause a person to struggle while performing regular activities. This is also why driving while high on marijuana is unsafe — THC affects the cerebellum and basal ganglia, which are two parts of the brain that regulate coordination, balance, and movement.

Marijuana use also affects mental cognition or thinking abilities. This can be especially dangerous for adolescents, as studies have shown that smoking marijuana as an adolescent can reduce a person’s IQ permanently. Some signs a teen may be abusing marijuana include failing grades, reports of skipping classes or not earning the grades to graduate on time.

Financial and legal troubles also go hand-in-hand with marijuana abuse. If someone gets caught selling or using the drug without a prescription, they could be arrested and face jail time, resulting in costly attorney fees and bail payment.

Marijuana Side Effects

When a person ingests cannabis, the drug releases THC (tetrahydrocannabinol) in the brain. This mind-altering chemical causes several effects, which may result in a person experiencing physical and psychological symptoms. These effects can occur in the short-term, even after one instance of marijuana use.

Physical Symptoms and Short-Term Effects of Marijuana

  • Increased heart rate by 20–50 beats per minute
  • Slowed breathing
  • Bloodshot eyes
  • Fainting
  • Falling
  • Orthostatic hypotension (dizziness when standing up quickly)
  • Heightened senses
  • Drowsiness
  • Slowed reaction
  • Imbalance and poor coordination
  • Increased appetite

Psychological Side Effects of Marijuana

  • Euphoria
  • Relaxation
  • Mood swings
  • Altered sense of time
  • Hallucinations
  • Paranoia
  • Anxiety
  • Panic attacks
  • Psychosis
  • Impaired judgment
  • Memory and learning problems

It’s not uncommon for people to also experience heart attacks following marijuana use, especially when it has a more potent concentration of THC. A person’s risk of heart attack can increase up to five times within the first hour after smoking marijuana. This is because it raises blood pressure and heart rate while reducing the blood’s ability to carry oxygen.

Signs of a heart attack include chest pain, lightheadedness, nausea or vomiting, neck, jaw or back pain, shoulder or arm pain, and shortness of breath.

A heart attack can be fatal and is a medical emergency. If you see someone experiencing the signs of a heart attack, call 911 immediately.

Long-Term Health Effects of Marijuana Use

The longer a person uses marijuana, the more exposed they are to THC and its effects. Over time, marijuana abuse can lead to the development of many dangerous conditions and adverse health effects.

Long-term side effects of marijuana use include:

Scientists have been doing significant amounts of research on how cannabis use affects mental capacity. For example, a recent Duke University study in New Zealand revealed that people who heavily smoked marijuana in their adolescent years and later became addicted to the drug lost eight IQ points between ages 13 and 38. Sometimes, the long-term effects of drug abuse can be repaired over time as the brain has a chance to heal in sobriety. However, this study showed these individuals did not regain their IQ points after they stopped using marijuana.

For women of childbearing age, marijuana use can also negatively impact pregnancy and unborn children. Using marijuana while pregnant has been known to cause low birth weight and an increased risk of stillbirth. Marijuana use during pregnancy has also been linked to brain damage in the developing fetus. Children born with prenatal marijuana exposure have shown:

  • Attention problems
  • Memory problems
  • Difficulty with problem-solving skills

Some preliminary research also shows that postpartum marijuana use can lead to an accumulation of THC in breast milk. If a nursing mother repeatedly uses marijuana, the THC levels in their breast milk could reach a high enough level to stunt brain development in their baby.

Extreme Symptoms of Consuming Too Much Marijuana

When a person ingests too much marijuana, an overdose (essentially drug poisoning) occurs. While overdose is commonly fatal with other drugs, there are no reports of a fatal overdose on marijuana alone.

You may have had a nonfatal marijuana overdose if you experienced these symptoms:

It’s possible to experience overdose on any form of marijuana, but it’s particularly likely when eating marijuana edibles. This often occurs because inexperienced edible users don’t realize how long it takes to feel the effects of the drug and eat an increased dose. This is more likely to occur with teenagers who have never taken edibles before, or even with small children who eat an edible without knowing it contains cannabis.

Although the overdose is typically nonfatal, it may be important to treat the overdose as a medical emergency and seek immediate medical treatment. One can visit their doctor’s office or a hospital right away. If you believe the person who has overdosed may harm themselves or others, it may be best to call 911 and let emergency personnel handle the situation.

If you or a loved one is struggling with marijuana use or addiction, The Recovery Village can help. Contact us today to learn more about treatment options and plans that can work well for your situation.

a man wearing a blue and white striped shirt.
Editor – Jonathan Strum
Jonathan Strum graduated from the University of Nebraska Omaha with a Bachelor's in Communication in 2017 and has been writing professionally ever since. Read more
a man smiling in front of a brick wall.
Medically Reviewed By – Eric Patterson, LPC
Eric Patterson is a licensed professional counselor in the Pittsburgh area who is dedicated to helping children, adults, and families meet their treatment goals. Read more

American Heart Association. “Heart Attack and Stroke Symptoms.” Accessed June 25, 2020.

National Institute on Drug Abuse. “Commonly Abused Drugs Charts.” Accessed June 25, 2020.

National Institute on Drug Abuse. “DrugFacts: Marijuana.” December 19, 2020. Accessed June 25, 2020.

National Institute on Drug Abuse. “Marijuana.” May 12, 2020. Accessed June 25, 2020.

American Medical Association. “AMA Applauds Surgeon General’s Advisory on Cannabis.” August 29, 2019. Accessed June 19, 2020.

National Institute on Drug Abuse. “Marijuana Research Report.” April 2020. Accessed June 19, 2020.

Duke University. “Adolescent Pot Use Leaves Lasting Mental Deficits.” August 27, 2012. Accessed July 7, 2020.

Medical Disclaimer

The Recovery Village aims to improve the quality of life for people struggling with substance use or mental health disorder with fact-based content about the nature of behavioral health conditions, treatment options and their related outcomes. We publish material that is researched, cited, edited and reviewed by licensed medical professionals. The information we provide is not intended to be a substitute for professional medical advice, diagnosis or treatment. It should not be used in place of the advice of your physician or other qualified healthcare providers.