Opioid-Induced Hyperalgesia: A Paradoxical Side Effect of Pain Medication

By: Robert Ealy |
Apr 9, 2024
Nurse Practitioner
SCCH Pain Management Clinic

Opioids are a class of medications that are commonly used to treat moderate to severe pain. They work by binding to opioid receptors in the brain and spinal cord, which blocks the transmission of pain signals. However, in some cases, long-term exposure to opioids can lead to a paradoxical effect called opioid-induced hyperalgesia (OIH).

What is OIH?

OIH is a condition in which exposure to opioids actually makes pain worse. This is because opioids can cause changes in the nervous system that make it more sensitive to pain. As a result, people with OIH may experience increased pain, even at lower doses of opioids.

Symptoms of OIH

The symptoms of OIH can vary from person to person, but they may include:

  • Increased pain sensitivity
  • Worsening pain with increasing opioid doses
  • Pain that spreads to new areas of the body
  • Allodynia, which is pain caused by non-painful stimuli, such as light touch or clothing
  • Hyperalgesia, which is an exaggerated pain response to painful stimuli

Risk factors for OIH

The risk factors for OIH include:

  • Long-term use of opioids
  • High doses of opioids
  • Certain types of opioids, such as long-acting opioids
  • Genetics · Underlying pain conditions

Diagnosis of OIH

There is no specific test for OIH, so the diagnosis is based on the patient’s clinical history and symptoms. The doctor will likely ask about the patient’s pain medication history, including the type of opioids, the dosage, and the duration of use. The doctor will also ask about the patient’s pain, including the location, severity, and any changes that have occurred over time.

Treatment of OIH

The best way to treat OIH is to reduce or taper off the opioid dosage. However, this can be difficult because people with OIH may have become dependent on opioids for pain relief. In some cases, the doctor may recommend switching to a different type of opioid or adding a non-opioid pain medication.

Prevention of OIH

The best way to prevent OIH is to use opioids only when necessary and for as short a period of time as possible. The doctor should start with the lowest effective dose and monitor the patient closely for signs of OIH.


OIH is a serious condition that can make it difficult to manage chronic pain. If you are taking opioids for pain, it is important to be aware of the risk of OIH and talk to your doctor about any concerns you may have.