Symptoms and Side Effects of Marijuana Abuse

Marijuana is a mind-altering drug that has several effects on the human body and mind. Even after one use, the person will show visible symptoms of smoking marijuana. The longer someone uses the drug, the more it will cause larger social changes in their life. If you’re worried a friend or family member may be abusing or addicted to marijuana, 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 abuse.

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 may seem enjoyable and the person may prioritize getting more marijuana over other activities they were previously dedicated to.

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

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

Social changes, for example, may include disinterest in former hobbies or friends, partaking in risky behaviors and a newfound interest in marijuana counterculture. For instance, 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 THC affects judgment, it 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, 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 your teen may be abusing marijuana are 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.

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

Some of the physical symptoms and side effects of marijuana use include:

  • Increased heart rate by 20–50 beats per minute
  • Slowed breathing
  • Bloodshot eyes
  • Fainting
  • Falling
  • Orthostatic hypotension, or dizziness when a person stands up suddenly
  • Heightened senses
  • Drowsiness
  • Slowed reaction
  • Imbalance and poor coordination
  • Increased appetite

Psychological symptoms of marijuana use include:

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

It’s not uncommon for marijuana users to also experience heart attacks following using the drug, 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, but reduces the blood’s ability to carry oxygen.

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.

Signs of a heart attack include:

  • Chest pain
  • Lightheadedness
  • Nausea or vomiting
  • Neck, jaw or back pain
  • Shoulder or arm pain
  • Shortness of breath

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:

  • Mental health problems
  • Chronic cough
  • Regular respiratory infections and chest colds
  • Drop in IQ
  • Addiction

Scientists have been doing significant amounts of research on marijuana’s effect on mental capacity. For example, a recent Duke University study in New Zealand revealed those who heavily smoked marijuana in their adolescent years and later became addicted to marijuana lost eight IQ points between ages 13 and 38. Sometimes, 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.

Heavy marijuana use in adolescence has also been linked to the developed of non-seminomatous testicular germ cell tumor — a unique form of testicular cancer that disproportionately affects young men. While testicular cancer is treatable and has a high survival rate, experiencing testicular cancer at a younger age can also impact a man’s fertility.

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
  • An increased risk of stillbirth

Using marijuana while pregnant 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 postpartum marijuana use can lead to an accumulation of THC in breast milk. If nursing mothers repeatedly use marijuana, the THC levels in breast milk could reach a high enough level to stunt brain development in their baby.

When a person intakes too much marijuana for the body to detox before the onset of dangerous side effects, 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 experienced a nonfatal overdose on marijuana if you experience these symptoms:  

  • Unease
  • Shaking
  • Extreme hallucinations
  • Extreme anxiety
  • Extreme paranoia

It’s possible to experience overdose on any form of marijuana, but it’s particularly likely when the person is 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 take an increased dose. This is an especially likely possibility with teenagers who have never taken edibles before, or even with small children who eat an edible not knowing it contains marijuana.

Although marijuana overdose is typically nonfatal, it’s still important to treat overdose as a medical emergency and seek immediate medical treatment. Visit your doctor’s office or a hospital right away. If you believe the person who has overdosed may harm themselves or others, particularly if they are experiencing extreme psychotic reactions, it may be best to call 911 and let emergency personnel handle the situation.

American Heart Association. “Warning Signs of a Heart Attack.” American Heart Association, 29 Sept. 2016, Accessed 23 Mar. 2017.

National Institute on Drug Abuse. “Commonly Abused Drugs Charts.” National Institute on Drug Abuse, National Institutes of Health, Jan. 2016, Accessed 23 Mar. 2017.

National Institute on Drug Abuse. “DrugFacts: Marijuana.” National Institute on Drug Abuse, National Institutes of Health, Feb. 2017, Accessed 23 Mar. 2017.

National Institute on Drug Abuse. “Marijuana.” NIDA for Teens, National Institute on Drug Abuse, Accessed 23 Mar. 2017.

National Institute on Drug Abuse. “What Are Marijuana’s Effects on Other Aspects of Physical Health?” National Institute on Drug Abuse, National Institutes of Health, Jan. 2017, Accessed 23 Mar. 2017.

Medical Disclaimer: The Recovery Village aims to improve the quality of life for people struggling with a 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 provider.

Marijuana Signs & Symptoms