Causes, Signs, & Effects of Drug Addiction

Are you concerned that you or a loved one may be struggling with drug addiction? Learn about the causes, signs, and effects to identify whether professional treatment may be necessary.

Understanding Drug Addiction

Learn about drug addiction

Substance abuse is a term that is used to describe the unhealthy use of illegal or legal drugs. This term includes the incorrect or excessive use of legal substances, such as prescription drugs or alcohol, and the use of illegal drugs such as methamphetamines, cocaine, or heroin. Substance abuse usually refers to an ongoing pattern of behavior, but it can also apply to a one-time occurrence.

Unfortunately, individuals who engage in substance abuse are at increased risk for becoming dependent on these substances, which is known clinically as developing a substance use disorder. If a person persists in using a substance, despite incurring problems related to that behavior, that individual may have a substance use disorder. Individuals who struggle with substance abuse and substance use disorders may persist in substance use despite health problems, accidents due to impairment, the urging to quit by loved ones, and even legal problems. Sadly, substance use is often associated with financial difficulties, family conflict, and even crime.

Substance use disorders often co-occur with other mental health diagnoses. For instance, depressive disorders or anxiety disorders may develop as a result of substance use, or they may be the root cause of the beginning of substance use. In many cases, it can be difficult to know the root cause of substance use. However, with dedicated treatment, these issues can be gently uncovered and healing may begin. Co-occurring treatment programs can help address these dual issues in one therapeutic location.

When a person develops a substance use disorder, he or she may be incapable of overcoming the compulsion to abuse a particular drug without proper professional intervention. The good news is that comprehensive treatment has proven to be effective in the effort to help men and women end their chemical dependence and make the lifestyle changes that allow them to live healthy, drug-free lives.


Drug addiction statistics

The National Institute on Drug Abuse (NIDA) has reported that between 80% and 90% of American adults have engaged in substance abuse at least one time in their lives. The three types of substances that are abused most often are prescription medications, alcohol, and marijuana. The Substance Abuse and Mental Health Services Administration (SAMHSA) reports that more than 20 million adults in the United States currently suffer from a substance use disorder; however, less than 15% of those individuals will receive treatment.

Causes and Risk Factors

Causes and risk factors for drug addiction

A number of risk factors and causes contribute to each case of substance use disorder. Each individual is unique, but the following risk factors may influence the development of substance use disorder:

Genetic: Research has found that genetics may be responsible for a large part of substance use disorders. For instance, 40% to 60% of all cases of alcohol use disorder (alcoholism) occur in individuals who have a family history of substance use disorder. Similar substance use disorders involving other legal and illegal substances tend to be influenced by family history of the disorder. Individuals who struggle with co-occurring mental health disorders along with a substance use disorder are more likely to have a family history of either mental illness or substance abuse. Some traits, such as impulsivity or novelty-seeking, may also be inherited, and may cause an individual to develop a higher risk of these disorders.

Environmental: An individual’s culture or peer group may reflect different attitudes about substance use, and certain substances may be more popular or more acceptable in some cultures than in others. Environmental stressors such as poverty, community or family violence, and traumatic experiences may also contribute to substance use.

Risk Factors: 

  • Substance abuse or substance use disorder among family members
  • Mental illness among family members
  • History of substance use
  • Experiences of trauma, including abuse or neglect, particularly in childhood
  • Exposure to substance use at an early age
  • Access to substances to abuse
  • Impulsive personality traits
  • Social groups or peers who engage in substance use
  • Impulsive tendencies
  • Aggressiveness, or desire to defy authority
  • Poverty and other environmental stressors

Signs and Symptoms

Signs and symptoms of drug addiction

Persons who engage in substance abuse or who struggle with a substance use disorder may display a wide variety of symptoms, including the following

Behavioral symptoms:

  • Isolation and withdrawal from others
  • Continuing to use substances despite consequences of punishment or loss
  • Using substances when it has become life-threatening, such as when driving
  • Hiding the truth about people, places, or actions
  • Missed time from work or school
  • Missing funds, which are often used to acquire more substance
  • Possession of drug paraphernalia
  • Hyperactive or slowed-down behavior

Physical symptoms:

  • Intense sweating, or clammy skin
  • Inability to sleep or sleeping too much
  • Slurred, slowed, or rapid speech
  • Pinpoint or dilated pupils
  • Changes in weight or appetite
  • Skin problems such as assesses, scabs, or sores
  • Headaches or nosebleeds
  • Fatigue
  • Restlessness or agitation

Cognitive symptoms:

  • Blackouts, where the person who appeared awake is unable to recall events
  • Disorientation and confusion
  • Poor judgment
  • Inability to plan, coordinate, or perform small or large motor functions
  • Racing thoughts
  • Inability to focus
  • Inability to recall information
  • Suicidal ideation or hopelessness

Psychosocial symptoms:

  • Agitation
  • Mood swings
  • Depression
  • Anxiety
  • Depression


Effects of drug addiction

Substance abuse will have a negative impact on an individual’s life in many ways, including:

  • Damage to major organs, resulting in severe illness
  • Diminished immune system
  • Exposure to life-threatening illnesses such as HIV/AIDS and hepatitis C
  • Family conflict, separation, divorce, or family violence
  • Increased risk of certain cancers
  • Lowered work performance
  • Damaged relationships
  • Legal problems such as arrest or incarceration
  • Financial difficulties
  • Job loss or demotions
  • Suicidal ideation or suicide attempts
  • Homelessness
  • Worsening or development of mental health disorders

Withdrawal & Overdose

Effects of drug withdrawal and overdose

Effects of substance abuse withdrawal: If a person has become dependent on a drug, and then suddenly drastically reduces use of that drug or stops using the drug altogether, that person may experience what is known as withdrawal. While each case is different and different substances will result in different withdrawal symptoms, there are some common effects of substance withdrawal, including:

  • Runny nose
  • Watery eyes
  • Intense cravings for the substance
  • Excess sweating
  • Difficulty sleeping or staying asleep
  • Vomiting, diarrhea, or nausea
  • Loss of appetite
  • Pain and aches in muscles and bones
  • Depression or excess anxiety
  • Seizures
  • Tremors or ticks
  • Abdominal pain and cramping

Effects of substance abuse overdose: Overdose is a serious and potentially life-threatening condition. If you suspect that you or a loved one has overdosed on any addictive substance, call 911 or seek immediate medical attention. The following are among the signs that may indicate overdose:

  • Inability to wake up
  • Shallow, labored, or slow breathing
  • Vomiting or diarrhea
  • Clammy, cold skin
  • Pinpoint or dilated pupils
  • Bluish-colored skin near fingernails or lips
  • Excess rise or drop in blood pressure
  • Loss of consciousness
  • Disorientation or confusion
  • Irregular heartbeat
  • Seizure

Co-Occurring Disorders

Drug addiction and co-occurring disorders

Often, substance abuse and substance use disorders will co-occur with a mental health challenge. In some cases, individuals begin using substances to avoid painful emotions or impulses, in other cases, mental health disorders develop as a result of substance use. Some commonly co-occurring disorders include:

  • Anxiety disorders
  • Schizophrenia
  • Bipolar disorders
  • Attention-deficit/hyperactivity disorder (ADHD)
  • Antisocial personality disorder
  • Depressive disorders
  • Posttraumatic stress disorder (PTSD)
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