What Is Drug Tolerance?

Drug tolerance is the reduction in body response to a particular drug or substance intake and has far-reaching effects on overall health and wellness.

Overview of Drug Tolerance

Many terms describe several different things in the drug use “space.” As a result, terms such as dependence, addiction, and tolerance often occur together or close to each other, and this has led people to assume they mean the same or are close to the same thing. However, this isn’t true at all.

This guide provides detailed answers to questions regarding drug tolerance, such as “What is drug tolerance?” and “Does drug tolerance mean the same thing as drug addiction?”

What Is Drug Tolerance?

Drug tolerance is when a person’s brain or the body stops responding to recreational or prescription medications in the way it used to respond. It often occurs when an individual has been on medication for too long. The medication’s ability to activate the enzymes or receptors in their body and brain at the same dose (initial dose) reduces, making it less effective.

So, for individuals with tolerance to enjoy the same body response to drug intake as they used to, they have to increase the dosage of the drug.

Does Tolerance Mean Addiction?

Tolerance doesn’t mean addiction, although the two terms are related. They’re different words with different meanings. People develop tolerance because their body is accustomed to a drug after taking it for a long time.¹ However, addiction to a drug refers to compulsive drug/substance abuse over time, which can cause drug tolerance. ²

How Does Drug Tolerance Develop?

Drug tolerance can develop in two ways, mainly behaviorally and physiologically. These are explained as:

• Behavioral Tolerance: Behavioral tolerance is learned. Drug effects may not be “felt” by users if they get accustomed to the environment in which they use the drug. Also, people can pretend not to be using the drug to counteract how it affects them. Lastly, if someone is informed or thinks a substance is more or less potent, they’re likely to feel and behave appropriately.
• Physiological Tolerance: Contrary to behavioral tolerance, this takes place at the cellular level. In physiological tolerance, the rate at which medications and substances of abuse are broken down and eliminated from the body increases. For instance, the liver will increase the production of the enzymes needed to break down alcohol when a person frequently drinks, allowing the body to get rid of it more quickly. This invariably results in “lessened” drug effectiveness, thus leading to drug tolerance.

What’s the Difference Between Drug Tolerance and Drug Dependence?

When a person’s body can no longer operate normally without taking a specific amount of a drug, they’re said to be drug dependent. It often happens when a person has been taking the same medication for a long time. It differs from drug tolerance when the brain stops responding to a drug because the body or brain has gotten used to it.

The main difference between these two terms is that someone that has drug dependence needs the medication for their body to work, while for drug tolerance, the drug has no significant effect on the body.

Types of Drug Tolerance

There are three main types of drug tolerance. These will be detailed below.

Metabolic Tolerance

When the body metabolizes drugs more quickly (quicker than usual), it’s said to have developed a metabolic tolerance. The medications will still have similar effects on the brain, but the drug will be eliminated quickly from the body, meaning that the impact of these drugs on the body will lessen, i.e., tolerance.

Physical Tolerance

Physical tolerance to drugs refers to a person’s ability to respond less strongly to drug use over time. As a result, higher dosages are required to get the same effect. Prescription medications like opioid painkillers frequently cause physical tolerance in their users. As a result, an individual who has developed an opioid prescription tolerance would need to consistently take greater doses to get the same pain relief as before.

Behavioral Tolerance

After using a drug for a while, a person’s behavior disruptions may become less noticeable. This is known as behavioral tolerance. This means that while drunk, such an individual may feel more functional due to behavioral tolerance to a substance. This type of tolerance is quite dangerous as it makes it difficult to determine if someone is battling addiction.

These individuals can go about some normal activities while still under the effect. Behavioral tolerance can also be risky since it might encourage drug users to drive or engage in other potentially dangerous behaviors.

Mechanisms of Drug Tolerance

Drug tolerance can occur in different ways, that is, according to several different mechanisms. They include pharmacodynamic resistance, metabolic tolerance, behavioral/learned tolerance, and conditioned tolerance. These will be discussed further below.

Pharmacodynamic Resistance

These are cellular alterations that result in dispositional and pharmacodynamic resistance. For instance, the body may develop fewer receptors on the surface of cells for the drug to interact with.

Metabolic Tolerance

This tolerance mechanism ensures that the medication or drug ingested is broken down and eliminated from the body system before reaching its site of action.

Behavioral or Learned Tolerance

This kind of tolerance allows people to get used to the effect of a drug. For example, long-term alcoholics can manage their alcohol with the same blood concentration.

Conditioned Tolerance

Environmental factors can also cause tolerance. For example, a person used to drinking at the bar might lose control when drinking at home, even with the same amount of alcohol.³

Drug Tolerance & the Drug Abuse Cycle

Drug addiction, drug abuse, and drug tolerance usually occur together. They occur in a cycle where one precedes and gives rise to the other. They’re collectively called the drug tolerance and drug abuse cycle.

A typical example of a drug tolerance and abuse cycle looks like an individual using a particular drug or substance of abuse and having a “high” or euphoric experience. The person then continues to take the drug to derive the same euphoric effect, but he realizes that he must keep taking more and more to attain the desired results (drug tolerance). When he starts to suffer some adverse effects, he suddenly realizes that he can’t stop using the medicine (drug addiction). Finally, it reaches a point where the person cannot afford to stop using the substance since he cannot function normally without it (drug dependence).

Physical Dependence

A series of physical symptoms might appear when an individual who has repeatedly taken a drug over time suddenly stops taking the medication. This can cause drug withdrawal effects which can be very severe.

Withdrawal Effects

Withdrawal effects occur after physical and physiological dependence have been manifested. The duration and severity depend on the medication, body physiology, and how long the person has been using the drug usually determines the duration and severity of these withdrawal effects.⁴
Some examples of withdrawal effects are hallucinations, vomiting, seizures, delirium, and nausea.⁵

Psychological Dependence

Psychological dependence is a mental and emotional process associated with drug use. During psychological dependence, the individual feels anxious or has mood swings and cravings if they don’t get the drug. This can be disastrous and can cause severe withdrawal symptoms.

What Are the Risks of Drug Tolerance?

There are several dangers and risks associated with drug tolerance. They are:

• Chronic pain
• Immune-related conditions
• Seizure disorders
• Some mental health conditions

Can Someone Stop Drug Tolerance from Occurring?

Halting the development of drug tolerance as far as prescription drugs are concerned is very difficult and, in some cases, quite impossible. The best solution as far as prescription drugs are involved is to use a mix of drugs and treatment approaches to halt the rate at which tolerance occurs.

Note, however, that abusing prescription drugs or failing to take them as directed can raise the chance of developing tolerance to the drug. With illicit drugs, tolerance is more or less assured with repeated drug use.

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

A few drugs can decrease or increase the blood concentrations of other drugs, which may interfere with how they function or reduce their potency.⁶

Warning Signs of Drug Tolerance Behavior

Here are some warning signs to know when your or someone you know has drug tolerance:

• Increased drug use
• Frequently refilling prescriptions
• Hiding pills
• Mood swings
• Excessive worry and anxiety
• Regularly talking about the chosen drug (obsession)
• Complaining about a drug being less effective

Get Help with Drug Tolerance at Alta Centers

Drug tolerance can be challenging to treat. However, if you discover it early, it makes the treatment process easier. Have you noticed any symptoms, or do you know someone with any of these symptoms?

If you do, then you should get treated. At Alta Centers, you will receive all the care and help you need to manage drug tolerance and addiction. Contact us today, and let’s help you live free from drug addiction.⁷

https://archives.drugabuse.gov/blog/post/tolerance-dependence-addiction-whats-difference
https://www.verywellmind.com/addiction-4157312
https://doi.org/10.1208/s12248-008-9056-1
https://www.verywellmind.com/what-is-withdrawal-how-long-does-it-last-63036
https://nida.nih.gov/publications/principles-drug-addiction-treatment-research-based-guide-third-edition/
https://www.ncbi.nlm.nih.gov/books/NBK442023/