What is Drug Tolerance?

Learn about drug tolerance and how it affects your physical and mental health. Locate available resources for addiction and dependence.

Table of Contents

Understanding Drug Tolerance

Drug tolerance, also known as insensitivity, is a concept describing diminished reactivity to a medication or drug with repeated usage. Increasing the drug’s dosage may re-amplify its effects; this may also hasten the effects of tolerance, further diminishing the drug’s effects. Drug tolerance is a sign of drug usage, but is not always linked to drug addiction or dependence.1 

When a person’s body or brain no longer responds to a prescription or drug in the manner it previously did, it is referred to as drug or medication tolerance. If a patient has acquired tolerance to their drug, their doctor might have to increase the amount.2

drug tolerance

Is it Genetic?

While genetic variables can predispose someone to addiction, there is no solid proof suggesting that substance tolerance is inherited. Several things can influence a person’s medication tolerance. People with kidney or liver diseases, the organs that break down or metabolize medications, may require different prescription dosages.

How it Affects the Brain

Prolonged drug usage and the development of addiction, tolerance, or dependence can have a harmful impact on the brain. Long-term drug use disrupts the way neurotransmitters send, receive, and process nervous system signals. Abuse may affect a person’s conduct as well as their capacity to think clearly and swiftly. All of these refer to drug tolerance psychology.3

What to Know About Drug Tolerance

In order to effectively diagnose and treat tolerance to drugs, it’s vital to learn more about what it is, how it occurs, and if it’s preventable.

Can Someone Stop Drug Tolerance from Occurring?

Regarding drug prescription, there is often no way to avoid the development of tolerance. Abusing or failing to take prescribed medications as directed might raise the possibility of medication tolerance, which is why it’s important to seek medical guidance.

Can Some Drugs Interact with Others and Increase the Risk of Tolerance?

Certain drugs can raise or decrease the blood concentrations of other medications, which may interfere with their effectiveness or mechanism of action.

Can External Factors Influence Drug Tolerance?

External variables such as illnesses and stress can affect a person’s medication tolerance. People who have unanticipated alterations in their capacity to acquire pharmaceuticals or changes in drug quality, such as purity, strength, and composition, may also change their tolerance.

The Difference Between Tolerance, Dependence, and Addiction

Many individuals use the phrases “tolerance,” “addiction,” and “dependency” interchangeably. While they might have similar meanings, they describe different circumstances. These differences will be detailed below.


Tolerance occurs when the same drug dose has less effect on a person’s body over time than it did initially.


Drug dependence occurs when a person’s body can no longer operate normally without a specific drug dose. This usually happens after long term use of the same drug.

Withdrawal occurs when a person with dependence decreases their drug dose or abruptly stops taking the drug, resulting in a number of physical and mental problems. People who are dependent on drugs must steadily lower the quantity of the drug they consume each day to diminish, limit, or even totally eliminate withdrawal symptoms.


Addiction is described as losing control over use of a specific drug while ignoring the negative consequences of doing so. Addiction is connected with long-term functional alterations in brain networks that govern learning, reward, and stress.4 

A person can get addicted to a substance if they use it regularly, which is similar to tolerance and dependence. However, drug addiction is a neurological disorder, unlike tolerance and dependence. According to some estimations, genetics can account for up to 50% of the chance of developing a drug addiction. Addiction is a complicated condition that may be controlled and treated, but there is no known cure at the moment.5

Warning Signs of Drug Tolerance Behavior

Tolerance doesn’t have to catch you off-guard. There are many signs of increased drug tolerance, including:

Increased Drug Use

Because the body is less tolerant of a specific drug, the patient has to use more of it to get the same result.

Frequently Refilling Prescriptions

Patients frequent stores that stock the particular drug they are craving, constantly refilling their prescriptions to get more of the substance they are hooked to.

Hiding Pills

People suffering from drug tolerance can be found hiding pills to ensure they always have a stash at hand.

Mood Swings

Drug-tolerant people often move through moods, a characteristic of alcohol and drug addicts.

Excessive Worry and Anxiety

This happens in two ways. Drug-tolerant patients suffer from worry and anxiety when they do not have their pills at hand. They also suffer from worry and anxiety during withdrawal and non-use periods.

Regularly Talking about the Chosen Drug (obsession)

Just as with drug addiction, drug-tolerant people constantly talk about how great the new drug is.

Complaining about a Drug Being Less Effective

Because drug tolerance increases the more a drug is ingested, patients progressively complain about how much less effective the drug is, not knowing their system is getting less tolerant of that same medicine.

Drug Tolerance – Mechanisms of Action

Mechanisms of tolerance refer to how individuals get addicted to certain drugs. Some of the mechanisms of substance tolerance will be discussed further below.

Pharmacodynamic Resistance

Pharmacodynamic tolerance develops when the biological reaction to a chemical diminishes after repeated usage. High absorptions of a chemical interact with the body receptor, desensitizing it over constant engagement–a common basis of pharmacodynamic tolerance.

Other causes include decrease in receptor density (generally linked with receptor agonists) or other processes resulting in changes in action potential firing rate. However, tolerance to a receptor antagonist entails the opposite (increased receptor firing rate, receptor density, etc.).

Metabolic Tolerance

Metabolic tolerance is when the body metabolizes medications quicker. Drugs still have identical effects on the brain, but will be eliminated swiftly by the body. Although the medications continue to influence the brain, the drug’s effects will reduce as the body processes the drug faster.

Behavioral or Learned Tolerance

Learned tolerance, or psychological tolerance, is when a person becomes accustomed to the environment where the drug is constantly ingested and does not “feel” its effects. Similarly, a person might act as if they are not using the medication and adjust to how it affects them. Finally, if a person is told or believes a substance is more or less potent, they will behave as reported.

Conditioned Tolerance

When environmental cues related to past medication administration are present, a larger dose of a medicine can be tolerated. In the absence of such stimulation, delivery of the drug may result in an overdose.

What are the Risks of Drug Tolerance?

Drug tolerance carries several hazards and consequences relating to physical and mental health conditions. The following are some of these risks:

  • Chronic Pain: Because of the impact that large doses of medications can have on the body, drug tolerance can also contribute to chronic pain or weakness.
  • Immune-Related Conditions: Drug tolerance can negatively impact the body’s immune system and its ability to fight off diseases. This can result in a variety of health problems that can have long-term consequences.
  • Seizure Disorders: Because over-reliance on drugs can affect the nervous system, drug tolerance also affects the nervous system by causing spasms and slight shakes that could deteriorate over time.
  • Mental Health Conditions: Drug tolerance can have a wide range of harmful mental health consequences. High doses of medicines take a toll on the mind, causing symptoms of sadness, anxiety, and trigger more severe mental health issues such as schizophrenia or psychosis.

How is Drug Tolerance Treated?

No singular method for treating drug tolerance has been found. Depending on the individual and their health, doctors typically provide specific plans to consider potential benefits, side effects, and dosages.

Prevention and Treatment

A doctor might advise you to take medicine in larger or more regular dosages. Alternatively, they may advise someone to wean off their medication by progressively taking less and less of it, so they can then begin taking a new drug.

Is Drug Tolerance Reversible?

The development of tolerance is a reversible process. Cross tolerance to the impact of pharmacologically similar medicines may develop, particularly those acting on the same receptor. It is important to note that both physiological and psychological reasons can lead to drug tolerance.

Acute vs. Chronic

Acute tolerance develops over a short amount of time, as seen in new cocaine users. Chronic tolerance develops over a long period of time, as observed in persons who use prescription opioids.

drug tolerance

Find Help For Drug Tolerance At Soledad House

To transition off drugs and mitigate potential withdrawal symptoms, many individuals require supportive and comprehensive treatment such as counseling or therapy. While the effects of tolerance can often be reversed, this is largely contingent on seeking swift and effective treatment.

Withdrawal symptoms can sometimes be fatal, especially if alcohol or benzodiazepine dependencies are involved. If you are experiencing severe withdrawal symptoms or drug side effects, do not hesitate to reach out for help.

Age, sex, underlying mental conditions, weight, drugs, or substance use may impact the effects of tolerance. You deserve treatment that is individualized for your medical history and desired outcome.

Why Soledad House?

If you find yourself or your loved one(s) suffering from drug tolerance and think you need guidance, then help is available at Soledad House. Here, we offer top-notch drug rehab services and offer drug tolerance psychology, ensuring you get the most value for your money.

Contact us today for more information and resources, and to discuss various available treatment options with our professionals.