Tolerance, Dependence, and Withdrawal

In substance use disorders, there are different factors that contribute to the disorder such as tolerance, dependence, and withdrawal.  There are some who believe that these three terms are interchangeable when in fact they are distinct terms and mean different things.

Tolerance
When a person uses alcohol or drugs repeatedly, the body begins to tolerate the amount ingested, whereby the individual needs to take more of the substance to achieve the same result.  Tolerance does not always indicate there is an addiction, as some individuals with chronic pain will need to take more of a prescription medication to alleviate pain.  There are three types of tolerance.  The first is acute, which means short term tolerance.  This is caused by repeated exposure to a drug over a short period of time and is seen with cocaine use.  Chronic tolerance is long-term and develops when the physical body adapts to repeated exposure to the substance.  Over time, the individual will need more of the substance to achieve the same “high”.  Learned tolerance occurs from frequent exposure to certain drugs.  An example of learned tolerance can be seen with individuals who drink alcohol for months or years but who do not appear intoxicated by others.

Dependence
Dependence and addiction are often used interchangeably but there are differences.  Dependence refers to a physical condition where the body has adapted to the presence of a drug.  Dependence is part of an addiction; however, dependence can also occur from use of non-addictive drugs such as prednisone, or synthetic steroids.  Individuals with allergies or autoimmune deficiencies can take this drug.  They may experience withdrawal symptoms if they stop taking the drug, but they are not “addicted” to it.  The same can be said for antidepressant medications.  There are withdrawal symptoms associated with stopping the drug; however, a person does not get addicted to antidepressants.  In these cases, a medical doctor will “titrate” a person off the drug slowly over time to reduce the withdrawal symptoms.

Dependence and addiction are interchangeable when a person stops taking a drug and experiences withdrawal symptoms.  If withdrawal symptoms are present, that person is said to be dependent on the drug.

Withdrawal
Withdrawal occurs when a person who is addicted to a drug, stops taking the drug.  When a person stops using a substance, the body rebounds by producing surges of adrenaline.  This adrenaline surge is what causes withdrawal.  Symptoms of withdrawal include headaches, depression, insomnia, and anxiety to name a few.  Every person’s physical withdrawal is different and even if a person does not experience physical withdrawal, they still may experience psychological withdrawal.