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Tolerance, Dependence, and Addiction: Knowing the Difference

The terms tolerance and dependence are often used when describing alcohol or drug addiction, but distinguishing the two similar terms can sometimes be challenging. However, each term means something different regarding how alcohol or drugs attack the body and brain. Though the medical terms are relatively direct, their association is not nearly as clear.

Many individuals question how someone can become addicted to drugs or alcohol. Some people misguidedly believe that anyone who abuses drugs or alcohol lacks a moral compass. In truth, it is the complete opposite. It is essential to spread awareness about why someone cannot simply quit their substance abuse.

Addiction is real. For those who become dependent on drugs or alcohol, quitting entails more than wanting to stop. Substances alter the brain's function, and the body exhibits withdrawal symptoms when the individual attempts to stop using the substance. Therefore, to collectively understand addiction, one must recognize tolerance, dependence, and addiction and what effects each has on the human body and brain.

Furthermore, explaining tolerance and dependence and how they relate to addiction can help individuals struggling with alcohol or drug use recognize addiction's various physical and mental factors and how it progresses.


According to The National Institute on Drug Abuse, tolerance is a loss of effectiveness of a substance with continual drug exposure. In other words, tolerance occurs when an individual no longer responds to drugs or alcohol the way they did when they first began using it.

The body adapts to the alcohol or drug, requiring increased amounts to feel the same effect. Consequently, individuals with substance use disorders start using more and more of the substance in a quest to try to feel the way they did the first time they used it.


Dependence occurs when a person stops using alcohol or drugs and their body experiences withdrawal symptoms. The body shows physical and mental signs of suffering when it does not receive the substance because it has become dependent on alcohol or drugs to function.

Withdrawal symptoms can range from mild to severe. Symptoms depend on the type of substance used, how long it was used, the individual's age and psychological characteristics, and the type of detoxification treatment used.

Symptoms can include:

  • Insomnia
  • Irritability
  • Mood swings
  • Depression
  • Anxiety
  • Body aches
  • Cravings
  • Fatigue
  • Hallucinations
  • Nausea
  • Paranoia
  • Confusion
  • Tremors
  • Disorientation

Along with the physical dependence of withdrawal symptoms, people can develop psychological dependence. Psychological dependence occurs when individuals believe they require alcohol or drugs to function. Sometimes the person can exhibit both types of dependency.


Addiction is a disease. While tolerance and dependence are not diseases, they can contribute to the condition and cause addiction to form if alcohol or drugs are being used continually. When individuals constantly use drugs or alcohol, even though they keep experiencing destructive consequences, they have an addiction to that substance.

How Substances Affect Brain Function

Substance use disrupts how neurons send, receive, and process signals through neurotransmitters. For someone who has an alcohol or drug addiction, the brain adjusts and increases dopamine levels when the substance is used, resulting in fewer neurotransmitters in the reward circuit for dopamine.

Brain circuits, known as dopamine pathways, are essential for natural rewards such as food, music, or exercise. Usually, the dopamine levels will increase in response to the natural rewards. However, when alcohol or drugs are used, dopamine levels increase substantially.

As a result, the brain no longer adjusts for natural rewards and only responds with alcohol or drug use. Fewer neurotransmitters are produced in the reward circuit, or the number of receptors that receive signals is reduced, creating an inability to experience natural pleasures.

The Correlation Between Tolerance, Dependence, and Addiction

The National Institute on Drug Abuse offers a simple explanation of the connection between tolerance, dependence, and addiction. The primary impression is that neither tolerance nor dependence alone creates addiction, and addiction can progress without the individual experiencing tolerance or dependency. Nevertheless, stopping alcohol or drug use without intervention becomes problematic when tolerance, dependence, and addiction assemble.

The transition from tolerance to dependence to addiction is not easily managed, so it is critical to acknowledge the differences to understand how to seek help. There is no definitive line to cross, and each phase can blend, making it difficult to know what phase an individual is going through. The emphasis is not on which stage a person is experiencing but on learning the signs of addiction as the condition progresses.

It is essential to increase awareness about why someone cannot simply quit their substance abuse, even when they desperately want to. Knowing when and how to get help can be overwhelming and confusing. Explaining tolerance and dependence and how it relates to addiction can assist individuals who struggle with alcohol or drug use to recognize addiction’s many physical and mental influences and how it develops. If you or a loved one struggles with alcohol or drug addiction, we are here to help. Present Moments Recovery center in San Diego, California, provides an individualized and comprehensive approach to addiction, with many levels of care to help you recover. Our family-run treatment center offers detox programs, inpatient and outpatient counseling, and sober living homes. At Present Moments Recovery, you can heal in a home instead of a facility. We believe recovery can only happen in the present moment. Call us today and learn more about our services at (619) 363-4767.



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Mark G
Mark Gladden brings both personal and professional experience to his role as co-founder of Present Moments Recovery. Now in long-term recovery himself after struggling with addiction for years, Mark understands firsthand the challenges men face in achieving and maintaining sobriety. It was this insight, combined with a desire to help others, that led Mark to establish Present Moments Recovery.

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