Some people use the terms “drug tolerance,” “addiction,” and “dependence” interchangeably, but they do not mean the same thing. Drug tolerance occurs when the body or brain does not respond to a drug the way it used to.

Drug tolerance is a commonly misunderstood term. It is not the same thing as addiction, and it can happen with both prescription and recreational drugs.

Read more to learn how tolerance happens, whether a high drug tolerance indicates addiction, answers to frequently asked questions, and more.

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Drug tolerance occurs when someone’s body or brain no longer responds to a prescription or recreational drug in the same way it once did.

In many cases, tolerance happens when someone has been taking a certain drug for an extended period of time. The receptors or enzymes in their brain and body are less activated by the drug, so it is not as effective.

This means that in order to experience the same effects they initially did, they need to increase their dose of the drug. A doctor can prescribe a higher dose of a person’s medication if they have developed a tolerance.

In cases of substance misuse, someone may need to take increasingly higher doses of the drug to achieve the “high” they are seeking.

Having a tolerance to a drug does not necessarily mean a person is addicted to it.

Many people develop a tolerance to a drug after taking it regularly for a long time. Their body becomes more accustomed to it, and the drug’s impact weakens.

In some cases, a person can also have a tolerance to a drug if they are addicted to it after taking it repeatedly over time.

There is no conclusive evidence suggesting drug tolerance is genetic.

A variety of factors can impact a person’s drug tolerance. People with certain liver or kidney disorders, the organs that break down or metabolize drugs, may require different drug dosages.

Additionally, someone’s age, sex, weight, underlying mental conditions, and drugs or substances they take at the same time as the medication may also impact their tolerance levels.

Many people use the terms “tolerance,” “resistance,” “dependence,” and “addiction” interchangeably. However, they are unique terms describing different conditions.


Drug tolerance happens when, over time, the same dose of a drug has less effect on a person’s body than it initially did.


Drug resistance occurs when a type of microorganism targeted by a drug — such as a bacterium, virus, parasite, amoeba, or fungus — mutates in a way that makes it less sensitive to the drug.

In simple terms, resistance means medications once used to treat infections or diseases caused by microorganisms are no longer effective. The microbes are able to continue living and replicating even in the presence of the drug designed to disable or destroy them.

Antibiotic resistance is an increasingly urgent problem that annually impacts about 2.8 million people living in the United States. Approximately 35,000 of them die from their antibiotic-resistant infection.


Drug dependency happens when a person’s body is no longer able to function as expected without taking a certain dose of a drug. It typically occurs when someone has been taking the same drug for an extended period of time.

People with a dependency are not necessarily addicted to the drug they have become dependent upon, but they can be.

If someone with a drug dependency suddenly stops taking the drug or reduces their dose, they will experience withdrawal. This can cause a series of mental and physical symptoms. In some cases, withdrawal can even cause life threatening symptoms, especially if someone is dependent on alcohol or benzodiazepines.

People with a drug dependency need to gradually reduce the amount of the drug they take each day to help lessen, limit, or even avoid withdrawal symptoms.


Similar to drug tolerance and dependence, a person can become addicted to a drug if they take it repeatedly. However, unlike drug tolerance and dependence, drug addiction is a neurological condition.

Addiction is defined as a loss of control over the use of a certain drug despite the negative consequences associated with taking it. People who are addicted to a drug will find themselves craving it and compulsively taking it.

It is associated with functional changes in neural pathways involved in stress, learning, and reward that can persist for a long time.

While there is no certain gene associated with drug addiction, someone can be predisposed to addiction by genetic factors. By some estimates, as much as 50% of the risk of developing an addiction is dependent on genetic makeup.

Addiction is a complex condition that can be managed and treated. However, there is currently no recognized cure for addiction.

Learn more about addiction.

People who experience drug tolerance often have questions about their condition, why it occurs, and what risks it poses. The following are frequently asked questions about drug tolerance.

Can someone stop drug tolerance from occurring?

In the case of prescription medications, there is often no way to prevent drug tolerance from developing. Misusing or not taking prescription medications as they are prescribed, however, can increase the risk of drug tolerance.

Can some drugs interact with others and increase the risk of tolerance?

Yes, some medications can increase or decrease blood concentrations of other medications, which may interfere with how effective they are or how they work.

Are there risks associated with developing drug tolerance?

One major risk associated with drug tolerance is that because a medication is not working as well, the condition it is treating may worsen.

People who develop drug tolerance may also be at an increased risk of misusing their medication.

Can external factors influence drug tolerance?

Yes, some external factors, including stress and illness, can influence a person’s drug tolerance.

People who experience unexpected changes in their ability to access medications or changes in the quality of drugs, such as the purity, strength, and composition, may also experience changes in their tolerance.

How does someone treat drug tolerance?

There is no specific way to treat drug tolerance. A doctor may suggest taking higher or more frequent doses of the drug.

Alternatively, they may suggest that someone wean off their medication by gradually taking less and less of it. Then they can start taking a new medication.

Someone may require additional supportive care, such as psychotherapy, to help them taper off medications.

Drug tolerance occurs when a drug becomes less effective over time.

Many people that need to take prescription medications on a regular basis eventually experience drug tolerance. They should talk with a doctor if a medication seems to become less effective, or if they find themselves using higher doses or taking a drug more frequently to get the same effect.