How Opioid-Induced Hyperalgesia can Lead to Addiction
To say that the United States is facing an opioid addiction crisis is nothing short of sobering reality. 1 in 3 people knows someone who is or was dependent on opioids. The Centers for Disease Control and Prevention estimate that the financial impact of opioid addiction in the U.S. is as high as $78.5 billion per year in lost productivity and wages, medical and addiction treatment, and criminal justice interventions.
And according to the National Institute on Drug Abuse, at least 130 people die every day from an overdose on either prescription or illicit opioid drugs. Let’s discuss Opioid-induced Hyperalgesia and Addiction.
As for the individuals who use heroin to support their opioid addiction, 80% of them were prescribed opioid medications before their illicit drug use. By all accounts, these individuals—who can be found on all socioeconomic scale stages—are simply searching for pain relief, entrusting their prescribing physicians, and unfortunately subjecting themselves to unintended consequences of mighty and problematic class drugs.
One unintended consequence of opioid use—aside from the grim reality of opioid addiction, dependency, and overdose—is a condition known as opioid use hyperalgesia. Described as early as 1943, the condition has become increasingly relevant within the past few decades as the dangers of opioid abuse and addiction have come to light.
Understanding opioid-induced hyperalgesia—including what it is, how it presents, and how it can be treated—is essential for anyone currently using opioids or knows someone who is. Without appropriate intervention, this condition can quickly take a person down an insidious path to addiction.
Why? Because in the case of hyperalgesia, the treatment of pain becomes the cause instead.
Understanding Hyperalgesia and How It Can Lead to Addiction
Opioid-induced hyperalgesia (OIH) is a heightened pain sensitivity (lowered pain threshold) due to chronic opioid exposure. Paradoxically, the person with OIH becomes even more sensitive to painful stimuli while taking opioids. This worsening pain sensitivity is often related to the original injury or condition for which a prescription was written. Alternatively, the pain may come from a different source—even in the absence of a new injury.
To put it another way, hyperalgesia is pain caused by the pain medication itself.
Consequently, a vicious cycle ensues:
Without realizing that their medication is triggering their pain, a person takes more and more prescription opioids to manage their symptoms (or self-medicate without physician supervision). This often leads directly to addiction and dependency—along with all the associated risks and detractions from a person’s quality of life.
Causes, Signs, and Symptoms of Opioid-Induced Hyperalgesia
How does opioid-induced hyperalgesia occur? This question’s answer is not yet fully understood nor agreed upon in the scientific literature and medical community. A leading theory is that the condition is driven by changes in the peripheral and central nervous systems, which cause pathways of pain perception to become more sensitive.
Hyperalgesia is often mislabeled as opioid withdrawal or opioid tolerance. It’s important for healthcare providers, individuals, and their loved ones to understand the differences between these conditions, as each one requires a different approach to treatment.
Key signs and symptoms of hyperalgesia stemming from Opioid Use include:
• Long-lasting pain
• Pain that is difficult for the person to define or describe; it is often different in quality from previously-experienced pain
• Pain that is decentralized or diffuse (rather than focal and in a specific area of the body)
• Pain not associated with any new injury or illness (it may seem to come on “out of the blue” or with no apparent cause)
• Pain felt from a source that doesn’t usually cause pain or is felt in areas other than the original pain site
Unlike opioid tolerance¬¬—in which a person needs more and more medication to relieve their pain—opioid-induced hyperalgesia leads to more pain as the dosage increases. Meanwhile, a person going through opioid withdrawal often experiences hyperalgesia in the form of diffuse pain and aches throughout the body. However, withdrawal by definition is caused by a relative decrease in dosage, not an increase seen with opioid-induced hyperalgesia.
Opioid-induced hyperalgesia can also be confused for or even co-occur with another condition known as allodynia. A person with allodynia will feel pain from non-noxious or benign stimuli, such as light touch or cold objects. For such individuals, opioids may help alleviate their pain, although other interventions with lower associated risks should be explored. Regardless, more opioids are never the answer for people with opioid-induced hyperalgesia.
Diagnosis and Treatment of OIH
A doctor may diagnose a person with opioid-induced hyperalgesia if they experience more pain even after taking a higher dose of their medication. Additionally, a physician should also consider a person’s medical background, rule out other conditions, and administer other diagnostic procedures, including quantitative sensory testing. An example of quantitative sensory testing is cold pressor latency, which assesses how long a person can tolerate their hand being submerged in ice-cold water.
Once opioid-induced hyperalgesia is diagnosed, the focus of treatment needs to be safe tapering off of the drug itself. This must happen with physician supervision because withdrawal symptoms can develop, leading to a great deal of physical, mental, and emotional stress for the individual—not to mention an increased risk of relapse.
Common treatment approaches to Opioid derived hyperalgesia currently include:
• Long-acting opioids including methadone or buprenorphine, particularly if an injury or illness is still present and causing pain—however, the effectiveness of these drugs can be poor in some cases
• Other medications including antidepressants and anticonvulsants
• Cognitive behavioral therapy
Each of these interventions poses its own risks and benefits. Treatment should be personalized and take a multifaceted approach that considers a person’s severity of symptoms, overall health status, lifestyle, social support, and length of opioid use.
Ultimately, recovery from hyperalgesia caused by chronic opioid exposure is possible, but the prognosis can vary between individuals. Raising awareness about this condition is essential for ensuring earlier detection and treatment while at the same time helping individuals live with less pain and greater quality of life.