What Is Metabolic Tolerance To Drugs Or Alcohol?

Medically Reviewed by Johnelle Smith, M.D. on September 2, 2022

Metabolic tolerance occurs when a person uses drugs or alcohol for an extensive period of time. This type of tolerance specifically occurs when the body becomes more efficient at getting rid of drugs or alcohol.

What Is Metabolic Tolerance To Drugs Or Alcohol?

Tolerance to drugs or alcohol occurs when a person needs higher and higher doses of the same substance in order to achieve the same effects.

Types of tolerance include metabolic tolerance, acute tolerance, and functional tolerance.

Metabolic tolerance occurs when the body becomes more efficient at eliminating the drug or alcohol as it is being used, even in high concentrations.

Tolerance can be dangerous, because it can lead to drug dependence or addiction as a person struggles to achieve the same high or effects they felt with their first dose or use.

Metabolic Tolerance: The Process Of Metabolizing Drugs Or Alcohol

Metabolism is an important part of a person’s biochemistry. Determinants for a person’s individual metabolism include their size, age, gender, genetics, phenotype, and diet.

Having metabolic tolerance is not necessarily related to whether a person has a healthy metabolism or characterization in general.

Metabolic tolerance is often found in people with obesity or an unhealthy body weight or body mass.

Metabolism with drugs and alcohol refers to the process of their intake, use, and excretion, and can be considered in four stages.

Stage 1: Absorption

The absorption stage of metabolizing drugs and alcohol refers to the intake of the substance.

Stage 2: Distribution

During the distribution stage is when uptake happens, and the body decides what it is going to keep during the metabolism process.

Stage 3: Metabolism

Liver enzymes are very involved in the metabolizing of alcohol and drugs, and so are certain proteins produced by amino acids. This process produces metabolites.

Stage 4: Excretion

Excretion refers to the elimination of drugs and alcohol outward as the body attempts to reach homeostasis.

Long-Term Effects Of Metabolic Tolerance

Metabolic tolerance can produce a number of potential long-term side effects.


There are strong affiliations between tolerance of any kind with dependence and addiction.

Metabolic tolerance will almost certainly contribute to physical dependence and addiction in many cases with drugs and alcohol.

As a person keeps drinking or using a drug more and more to account for their tolerance, they may then find themselves relying on that substance in order to feel normal. They may no longer be able to function without it.

Organ Damage

When organs like the liver, lungs, and kidneys are worked harder than usual in order to expel waste from the body, it can cause a great deal of damage with time.

Though metabolic tolerance allows these organs to eliminate waste faster, this does not mean it is good for them.

For instance, with metabolic tolerance involving alcohol, a person’s liver and hepatic system has to work extra hard to filter out the extra ethanol it is being fed to compensate for tolerance.

Increased Toxicity

A person with metabolic tolerance is at an increased risk for overdose or death, because they can easily overestimate how much of a drug or alcohol is in their body.

This is because, with tolerance, they don’t feel the usual impairment that they would from such stimuli.

In an attempt to counteract their metabolic tolerance, a person may simply take too large of a dose.

Treatment Options For Drug Abuse

Tolerance is often a sign of addiction, which most often requires professional treatment.

Every substance abuse treatment center is unique and will have its own amenities and therapies when it comes to treating addiction.

The following are some of the treatment options you will find available at most healthcare centers for addiction.

Treatment options for drug abuse include:

  • residential treatment
  • partial hospitalization programs
  • cognitive behavioral therapy
  • dialectical behavior therapy
  • pharmacology support
  • medication-assisted treatment
  • case management
  • court-ordered rehab

Find Substance Abuse Treatment Today

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Please do not hesitate to reach out to us for help — we are always available to answer any and all questions you have regarding addiction treatment.

Give our free and confidential helpline a call when you are ready to get started.

This page does not provide medical advice. See more

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Medically Reviewed by
Johnelle Smith, M.D. on September 2, 2022

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