Drug & Alcohol Tolerance

Adapting to Presence of a Substance

Tolerance is the condition in which a person’s body responds to the presence of a constant amount of drugs or alcohol. As a person uses a substance more regularly, the body will become used to the presence of that substance and adapt its normal responses accordingly. Tolerance develops and can lead to dependence and addiction to the substance. The person will require more of the substance to achieve the same level of intoxication or the same high. There are a number of different types of tolerance that occur in a person when they have a substance abuse problem.

Tolerance to alcohol or other drug affects a person’s drinking or drug taking behavior. Some individuals may obsessively seek out drugs, take more drugs more often or binge drink to achieve the level of intoxication they desire. Some substance abusers will change their drug or preferred drink to a stronger and more harmful substance.

Once a person’s body has become used to the presence of drugs or alcohol in the body all the time, they will experience withdrawal symptoms if they stop using. The brain expects the substance to be there and has adjusted the chemicals in the brain accordingly. If the drug abruptly is not present, a chemical imbalance occurs in the brain and rapid changes occur such as mood swings, thought processing and body functions.

Tolerance Causes Chemical Changes

Tolerance typically occurs after long term, chronic use of a substance. With increasing tolerance to the drug, more is required to get the same effect. Tolerance and dependence develop as the nerve cells chemically and structurally counteract the drug’s effects. A complex chain of molecular and receptor changes occur in the brain when a drug is in the body and stimulates the release of dopamine from the dopamine receptors in the brain. When the receptors are stimulated, a person will experience feelings of pleasure and well-being.

If a person uses the drug continuously, the receptors in the brain will be hyper-activated and the body will make changes to adjust the levels of chemicals in the body that may cause harm. The brain can turn off some of the receptors in the brain that are being constantly stimulated to counteract the effects of the drug, resulting in tolerance to the drug. A person can continue to use the drug at the same level but not feel the effects.

Dependence Results in Tolerance

Dependency is the persistent, compulsive and repetitive use of a substance that results in tolerance. Dependence on a drug can be both physical and psychological. Some drugs such as heroin and alcohol will cause a person to exhibit painful physical symptoms when they are not using the drug or if they attempt to stop using the drug without medical support. Cocaine addiction leads to intense cravings that last for months and sometimes years.

To say that an individual is psychologically dependent means that they experience cravings. It also means that even the idea of not using the substance, or engaging in the behavior, will cause them discomfort. They now feel that they need this crutch to make it through the day. It may be difficult to imagine life without it. The individual with devote much of their time to thinking about the addictive substance. They may be in complete denial as to the extent to which this behavior is damaging their life.

Tolerance and Withdrawals

Withdrawals are the symptoms associated with stopping use of alcohol or drugs that the body has become tolerant of and dependent on. These withdrawals can be unpleasant and may even prove to be fatal. Along with the physical discomfort the individual will experience, there is a level of psychological pain that a person will also go through. Fear of such effects can discourage people from trying to escape their addiction.

Physical symptoms that a person may experience when withdrawing from drugs or alcohol include body shakes and tremors, nausea, sweating, heart palpitations, muscle aches, seizures, diarrhea, headaches and insomnia. These symptoms can last for a few hours to a few days or longer. The severity of these symptoms and the anxiety they cause can often be managed or reduced with support from friends, family or medical professionals.

Delirium tremens are a particularly severe symptom of withdrawals that are usually associated with chronic alcohol use or benzodiazepines and barbiturates abuse. Those at risk of developing delirium tremens should be monitored by a medical professional, as they are potentially fatal. Symptoms include convulsions and seizures, elevated blood pressure, high levels of confusion, agitation, anxiety and hallucinations.

Physical dependence can occur with alcohol and drug abuse. The body changes in response to the persistent use of these substances, and tolerance increases. If the level of the substance in the body falls too low, the individual will begin to experience withdrawal symptoms. In some instances, these symptoms can be so severe that they prove fatal. Even people who are using prescription medication can develop physical dependence if they use the drug for long enough and at a high enough dose.