Substance Use Disorder

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Substance use may begin with experimental or recreational use of a substance. As the use becomes more frequent, substance use disorder affects a person’s brain, leading to a lack of control over the use of the substance. Over time, individuals with substance use disorder need more and more of the drug to experience the same effect.

While a person with substance use disorder may want to stop using the drugs or alcohol at the center of their illness, it becomes increasingly more difficult to live without the substance. In some cases, stopping the drug can cause intense cravings and severe withdrawal symptoms.

Symptoms of Substance Use Disorder

Signs of substance use disorder differ depending on the substance and the individual. Many sufferers become very good at hiding their addiction, while others show more obvious signs. Symptoms of substance use disorder may include:

  • Cravings for the drug which cause a person to ignore everything else
  • Needing more of the substance to get the same effect
  • Buying the drug even in the face of financial difficulty
  • Making it a priority to have an adequate supply of the substance
  • Failing to meet responsibilities at work or school
  • Withdrawing from social activities
  • Doing things to get the drug that a person wouldn’t do otherwise
  • Using the drug despite wanting to stop and evidence of its harm
  • Spending more and more time with the substances, whether acquiring it, using it, or recovering from its effects
  • Experiencing withdrawal symptoms when the drug isn’t taken
  • Physical health problems, such as changes in weight, lack of energy, or red eyes
  • Lack of interest in one’s grooming or appearance
  • Sudden changes in behavior, such as becoming more secretive or spending more time alone
  • Financial issues, including requests for money that have no reasonable explanation, or the discovery that money or other items have been stolen

Substances and Related Signs of Intoxication

Marijuana, hashish, or other cannabis products

  • A sense of euphoria or a heightened sense of perception
  • Increased blood pressure and heart rate
  • Dry mouth
  • Red eyes
  • Memory difficulties
  • Slow reaction or decreased coordination
  • Anxiety or paranoia
  • Food cravings

Synthetic drugs such as K2, bath salts or spice

  • Elevated mood, sociability or sense of euphoria
  • Increased energy
  • Extreme agitation
  • Anxiety, paranoia, or panic attacks
  • Cardiac symptoms, including increase heart rate, pulse, and even cardiac arrest
  • Confusion or hallucinations
  • Increased sex drive
  • Vomiting
  • Loss of coordination
  • Violent behavior

Barbiturates, benzodiazepines and hypnotics

These prescription drugs depress the central nervous system. Symptoms may include:

  • Drowsiness
  • Mood swings or irritability
  • Dizziness, lack of coordination, falls
  • Slurred speech
  • Memory or concentration problems
  • Involuntary eye movements
  • Slowed breathing
  • Reduced blood pressure
  • Lack of inhibition

Meth, cocaine and other stimulants

Stimulants are often used to boost energy, improve performance at work or school, or lose weight. Symptoms of recent use may include:

  • Excessive confidence
  • Increased energy or alertness
  • Behavior changes
  • Rapid speech
  • Dilated pupils
  • Irritability, anxiety, or paranoia
  • Confusion or hallucinations
  • Increased heart rate or blood pressure
  • Nausea or vomiting
  • Poor judgment
  • Mouth sores, gum disease, tooth decay, damage to the nasal mucous membrane
  • Insomnia
  • Depression

Club Drugs

Examples are ecstasy or molly (MDMA), GHB, “roofies” (flunitrazepam), and ketamine. Signs and symptoms of use may include:

  • Hallucinations
  • Dilated pupils
  • Anxiety or paranoia
  • Chills, sweating, tremors, clenched teeth, or muscle cramps
  • Behavioral changes
  • Lack of coordination or muscle control
  • Poor judgment
  • Memory problems or inability to concentrate
  • Changes in blood pressure or heart rate
  • Reduced consciousness


Substances that are commonly inhaled include glue, gasoline, butane, paint thinners, and cleaning fluids. Signs and symptoms of use include:

  • A brief sense of euphoria
  • Aggressiveness or combativeness
  • Nausea, or vomiting
  • Irregular pulse
  • Tremors
  • Dizziness or poor coordination
  • Involuntary eye movements
  • Slurred speech
  • Rash around the nose or mouth


The most commonly ingested hallucinogens are lysergic acid diethylamide (LSD) and phencyclidine (PCP). Symptoms of use include:

  • Hallucinations
  • Rapid mood swings
  • Reduced or changed perceptions
  • Increased heart rate or blood pressure
  • Tremors or lack of coordination
  • Violence or aggression
  • Involuntary eye movements
  • Problems speaking
  • Difficulty with memory or concentration
  • Hypersensitivity to loud noise
  • Impaired judgment
  • Inability to feel pain
  • Seizures or coma


Among others, opioid painkillers include heroin, morphine, codeine, oxycodone, and methadone. Signs and symptoms of use include:

  • Reduced ability to feel pain
  • Slurred speech
  • Drowsiness or appearing sedated
  • Constricted pupils
  • Agitation
  • Problems with memory, confusion, or paying attention
  • Slow movements or lack of coordination
  • Depression
  • Decreased rate of respiration
  • Constipation
  • Runny nose
  • Needle marks

When to Seek Help

Call 911 immediately if you or someone you know displays any of these symptoms:

  • Shows changes in consciousness
  • Has trouble breathing
  • Has seizures or convulsions
  • Has heart attack symptoms, such as chest pain
  • Seems to be unaware of their surroundings or disconnected from reality

Make an appointment to see a doctor if:

  • You have tried and failed to stop using the substance, despite the desire to do so and the harm the substance causes.
  • Use of the substance has led to risky behaviors, including unprotected sex or sharing needles.
  • You are experiencing withdrawal symptoms.
  • Someone you love has experienced any of the symptoms above.

Treatment Options

Substance use disorder is treatable, but the method of treatment depends on the substance used and the individual’s comprehensive medical circumstances. Treatments may include:

  • Psychotherapy to discover the underlying causes of substance use and learn coping strategies
  • 12-step or other recovery models
  • Inpatient treatment
  • In the case of opioids, medication to reduce cravings
  • Alternative therapies such as exercise and mediation