Addiction, Physical Dependence, and Tolerance to Pain Medication

There is a difference between addiction, physical dependence, and tolerance to pain medication. It is imperative that each of us understands the difference.

Many people with chronic pain conditions, including certain types of arthritis, are prescribed pain medication. Their medical condition dictates the need for such drugs—that's why it was prescribed as part of their treatment plan. Yet, if you pay attention to the news, people who are legitimately prescribed pain medication are being lumped in with the abusers. We can easily understand how that developed. After all, there is an epidemic of opioid abuse in the U.S. The drugs are said to be overprescribed. Add to that a celebrity dying from a drug overdose and the anti-drug campaigns hit a fever pitch.

Each of the aforementioned problems is a legitimate concern. But, so is the disregard for people (e.g., chronic pain patients) who legitimately need pain medication to function and have some quality of life. Their plight cannot be minimized while the urgency of other matters is dealt with. This realization has largely been lost because too many people do not understand the difference between addiction, physical dependence, and tolerance. We cannot blur the lines between these three factors and expect to solve problems related to drug use and abuse. It is the first step we all must take—understanding the terminology. 

What Is Addiction?

The American Society of Addiction Medicine (ASAM), the American Academy of Pain Medicine (AAPM), and the American Pain Society (APS) recognize the following definition of addiction as it relates to the use of opioids for the treatment of pain:

Addiction is a primary, chronic, neurobiological disease, with genetic, psychosocial, and environmental factors influencing its development and manifestations.

What Is Physical Dependence?

The American Society of Addiction Medicine (ASAM), the American Academy of Pain Medicine (AAPM), and the American Pain Society (APS) recognize the following definition of physical dependence:

Physical dependence is a state of adaptation that is manifested by a drug class specific withdrawal syndrome that can be produced by abrupt cessation, rapid dose reduction, decreasing blood level of the drug, and/or administration of an antagonist.

What Is Tolerance?

The American Society of Addiction Medicine (ASAM), the American Academy of Pain Medicine (AAPM), and the American Pain Society (APS) recognize the following definition of tolerance:

Tolerance is a state of adaptation in which exposure to a drug induces changes that result in a diminution (i.e., diminishing or lessening) of one or more of the drug's effects over time.

That said, most pain medicine and addiction specialists concur that chronic pain patients treated longterm with opioid drugs usually do develop physical dependence. Some patients will develop tolerance. But, usually, this group of patients does not develop an addiction. The actual risk of addiction is considered unknown and not predictable, but it is likely related to several factors, including genetic predisposition.

Addiction itself is a primary chronic disease. Exposure to drugs is just one factor in its development. In fact, in most cases, exposure to drugs that can stimulate the brain's reward center do not produce addiction.

Characteristic Features and Behaviors

Impaired control, craving, and compulsive use of the drug, as well as continued use of the drug despite negative physical, mental, or social consequences, are considered characteristic features of addiction. But, it can be a bit more complicated than simply recognizing the presence of those features. The same features could be related to inadequate pain relief. A doctor must be able to exercise their judgment and to discern between addiction and another cause.

There are specific behaviors that point to the possibility of addiction. Those behaviors include:

• Not adhering to the prescribed schedule for the drug
• Taking more than one dose at a time
• Repeated reports of stolen or lost drugs
• Doctor shopping (getting the drug from more than one doctor)
• Isolation (wanting time alone)
• Additionally using non-prescribed psychoactive drugs
• Using pain medications for sedation, intoxication, to boost energy, or to lower anxiety levels
• Requesting certain formulations or routes of administration of the drug
• Avoidance of or disinterest in non-opioid treatment options

Addiction clearly is associated with potentially serious, even fatal, consequences. On the other hand, physical dependence is considered a normal response by the body to the chronic or continued use of certain medications—and not only opioid pain medications. For example, physical dependence can occur with corticosteroids, antidepressants, beta-blockers, as well as other medications not considered addictive. If drugs that may be associated with physical dependence are to be discontinued, the drug should be tapered to avoid withdrawal symptoms (e.g., prednisone tapering).

Tolerance is even a bit trickier to understand. Tolerance may occur to the desired effect of the drug, but it can also occur to the undesired effects. Tolerance is also variable, occurring at different rates for different effects. Using opioids as an example, tolerance to the analgesic effects occur more slowly than to respiratory depression.

The Bottom Line

Addiction is mostly a behavioral disorder, although it can overlap with physical dependence. Typically, addiction involves using the drug despite negative consequences, craving the drug even when not in physical pain, and using it for reasons other than the prescribed indication. Physical dependence is evident when someone develops a tolerance to a drug or if one would experience withdrawal symptoms from stopping the drug suddenly. Tolerance is present when the same dose does not garner the same result, thereby requiring higher doses to achieve the desired result. In and of itself, physical dependence does not mean that there is addiction, but it may accompany addiction when there is addiction.