Marijuana Effects & Warning Signs

Marijuana, also commonly referred to as weed, pot, and reefer, consists of dried stems, leaves, and flowers of the cannabis plant. This drug, which is most often abused by smoking, may also be eaten (usually as an ingredient in foods, such as brownies or cookies) or steeped into a tea.

Understanding Marijuana

Learn about marijuana and substance abuse

Marijuana trails only alcohol and tobacco on the list of most commonly abused drugs in the United States.

The primary effects of ingesting marijuana are slight disorientation and/or dizziness, slowed reaction times, and increased appetite. These effects are the result of marijuana containing THC (tetrahydrocannabinol), a naturally occurring substance with mild analgesic properties.

The United States Department of Justice (DOJ) has classified marijuana as a Schedule I controlled substance. Schedule I drugs are those that possess no currently accepted medical use and a high potential for abuse.

According to the National Institute on Drug Abuse (NIDA), about 1 of every 11 marijuana users will become addicted to the drug, with younger users and daily users being at the greatest risk for developing an addiction. Fortunately, marijuana abuse treatment options are available that can help these individuals return to a life of sobriety.


Marijuana abuse statistics

Despite marijuana’s classification as a Schedule I drug, experts estimate that about 104 million Americans have used the substance at least once in their lives, 25 million Americans have used it in the past year, and more than 14 million Americans describe themselves as regular users.

In 2013, more than 690,000 Americans were arrested for violating marijuana laws. According to the Drug Abuse Warning Network (DAWN), marijuana use was involved in 376,467 emergency room visits in 2009. Heroin, amphetamine, and methamphetamine use accounted for a combined 306,680 ER visits in the same time period.

Globally, the World Health Organization (WHO) estimates that about 147 million people (or about 2.5% of the Earth’s population) use marijuana every year.

Causes and Risk Factors

Causes and risk factors for marijuana abuse

Several factors can place an individual at an increased risk for abusing or becoming addicted to marijuana or another illicit drug. Researchers have identified several genetic and environmental precursors to addiction, as well as a host of general risk factors that increase a person’s susceptibility to substance abuse.

Genetic: Several studies strongly suggest the presence of a genetic predisposition for substance abuse and addiction. People whose parents struggled with addiction are much more likely to develop an addiction themselves than are people who do not have addiction in their family history. As many as 266 genes have been identified as playing part (either individually or in networks) in increasing or reducing the likelihood that a person will experience a problem with substance abuse and addiction.

Environmental: Family history of marijuana abuse can also be an environmental factor, as children who grow up in households where marijuana is used openly are more likely to engage in similar behavior than are those whose parents forbade the use of marijuana. Other external or environmental factors that can influence the development of a substance abuse problem include living in a neighborhood or community where drug use is common, associating with friends or colleagues who use drugs, being pressured to use drugs, or suffering from stresses, pressures, or traumas that prompt one to self-medicate with marijuana or a similar substance.

Risk Factors:

  • Having parents or siblings who abuse marijuana
  • Family history of mental illness
  • Suffering from an anxiety disorder, a depressive disorder, or other type of mental illness
  • Personal history of abusing other illicit substances
  • Personal history of trauma or abuse

Signs and Symptoms

Signs and symptoms of marijuana abuse

Evidence that a person has been abusing marijuana depends upon a number of factors, and thus, no single symptom or set of symptoms will manifest in all cases of marijuana abuse. However, the following are common indicators that a person may be abusing marijuana:

Behavioral symptoms:

  • Withdrawal from family members and previously close friends
  • Decline in attention paid to one’s appearance and personal hygiene
  • Becoming secretive or otherwise deceptive about one’s actions or whereabouts
  • Unexplained decline in performance on the job
  • Eating binges, often involving junk food or fast food
  • Possession of drug paraphernalia (especially roach clips, small pipes, and water bongs)
  • Engaging in fits of laughter or giggling

Physical symptoms:

  • Poor coordination
  • Overall sense of lethargy
  • Distinct odor
  • Hunger
  • Dry mouth
  • Bloodshot eyes

Cognitive symptoms:

  • Confusion
  • Disorientation
  • Sensory distortion
  • Memory difficulties
  • Delayed reaction time
  • Inability to focus or concentrate
  • Difficulty tracking the passage of time

Psychosocial symptoms: 

  • Expressions of paranoia
  • Euphoria, followed by depression
  • Agitation
  • Irritability
  • Loss of interest in people, events, and/or issues that were once of great importance

Co-Occurring Disorders

Marijuana abuse and co-occurring disorders

Marijuana abuse often occurs along with other disorders that may have either led to or been caused by the substance abuse. Co-occurring disorders can significantly undermine a person’s effort to stop using marijuana. As a result, effective treatment should identify and address any of the following co-occurring conditions:

  • Panic disorder
  • Other types of anxiety disorders
  • Major depressive disorder
  • Persistent depressive disorder
  • Attention-deficit/hyperactivity disorder (ADHD)
  • Bipolar disorder


Effects of marijuana abuse

Marijuana abuse puts users at risk for both short- and long-term health effects. Depending upon the amount of marijuana a person has been using, and the length of time he or she has been using the drug, these effects can range from bothersome and temporary to devastating and permanent.

The following are among the more common physical and psychological effects of marijuana abuse:

  • Abuse of and addiction to alcohol and other drugs
  • Sexual performance problems
  • Increased susceptibility to illnesses, such as the common cold
  • Increased risk of lung damage
  • Increased risk of infections of the upper respiratory system
  • Increased risk of developing certain types of cancer
  • Bruises, sprains, and broken bones due to slips and falls
  • Legal problems (both from the drug use itself and from associated reckless behaviors)
  • Employment problems (from the drug use itself, from associated reckless behaviors, and/or from resultant legal problems)

Withdrawl & Overdose

Effects of marijuana withdrawal and overdose

Marijuana use can lead to both tolerance and dependence. Tolerance means that users will need to ingest increasingly larger (or more potent) doses to achieve the same high that previously resulted from smaller doses. Dependence means that the absence of the drug can trigger several physical and psychological symptoms.

The following are among the more common symptoms of marijuana withdrawal:

  • Mood swings
  • Dizziness and shakiness
  • Concentration problems
  • Insomnia
  • Loss of appetite
  • Depression
  • Impotence
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