Hyperalgesia: Causes, Types, Symptoms, Diagnosis and Treatment

It is a condition in which a person develops a greater pain sensitivity.

What may not harm most people can cause significant pain in a person with hyperalgesia.

Although there are many potential causes associated with hyperalgesia, it is believed that the condition results from changes in the nerve pathways, which cause the nerves of people to have an overactive response to pain.

There are medications available to prevent a person’s symptoms from getting worse.

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Hyperalgesia can be very difficult to diagnose for a doctor.

There are different types of hyperalgesia, and doctors have a variety of theories about why people experience it.

Researchers are also studying a potential genetic link with hyperalgesia.


The condition is very similar to tolerance to medications and drug extraction.


There are several nerves or “pain” pathways in the body where signals can start to communicate poorly, resulting in hyperalgesia.

Some scientists think hyperalgesia occurs when the chemicals known to reduce pain are altered; others propose that it occurs when “crossed cables” in the nervous system prevent pain signals from being transmitted accurately.


Doctors generally divide hyperalgesia into primary and secondary categories. Both conditions are due to initial tissue trauma and inflammation.

Primary hyperalgesia:

It occurs when there is an increase in pain in the tissue where the injury occurred. An example would be when a person has surgery on the elbow, and the pain worsens over time instead of getting better.

Secondary hyperalgesia:

It occurs when the pain seems to extend to non-injured tissues or tissues.

Other types of hyperalgesia:

Another type of hyperalgesia is opioid-induced hyperalgesia (OIH). It occurs when a person experiences a worsening or new pain due to taking opioids, such as morphine, hydrocodone, or fentanyl, to relieve pain.


The main symptom of hyperalgesia is an increasingly extreme reaction to painful stimuli without new lesions or the worsening of a medical condition.

An example would be a surgical incision that becomes more painful over time; however, the wound is not infected, and a person has not experienced any additional injury.

Hyperalgesia is different from drug tolerance, although the two processes are similar.

If a person develops a tolerance to a particular drug, it usually means that their body has become accustomed to the presence of the drug in the current dose, and the drug is no longer functioning correctly.

When a person has developed a tolerance to medication, increasing the dose will usually decrease a person’s pain.

Tolerance to medications is different from hyperalgesia, where the increase in pain medications will not reduce the amount of pain a person feels. Sometimes increasing the pain medication worsens the person’s pain.

Another similar medical condition is allodynia. This condition is where a person develops a significant pain response to non-painful stimuli. Even brushing a person’s skin can cause pain.

In hyperalgesia, a person has experienced a painful stimulus, such as cancer pain or pain after surgery, but their response to pain is greater than the expected pain level.


The diagnosis can be difficult for a doctor.

Hyperalgesia can present difficulties for a doctor to treat because a person may have developed OIH.

A doctor will take a medical history and review a person’s medication to make a diagnosis. They can also ask questions about the nature of their pain.

Some of the signs that may indicate hyperalgesia include:

The pain extends beyond the area where a person experienced an initial injury or felt pain earlier. Examples could include headaches, neck pain, and leg or back pain.

Some people describe the pain as “diffuse” or spread. Some may report pain and pain throughout the body.

The quality or experience of pain is different from what it used to be. The pain can become acute, painful, or stabbing, where previously, the person felt the pain differently.

A doctor can increase a person’s pain medication to determine if the cause is hyperalgesia. If the additional pain reliever causes more pain, the condition may be hyperalgesia.

Currently, there are no definitive diagnostic tests for hyperalgesia.



Reducing the dose of opioids to treat hyperalgesia may be recommended by a doctor.

If opioids induce hyperalgesia, a doctor may reduce the dose. While a person may experience an initial increase in pain due to these changes, this often gives way to a reduced pain experience in those with hyperalgesia.

A doctor may also try to prescribe an alternative, non-opioid medication.

There are also different classes of opioids that a doctor could prescribe. An example is a methadone, a medication that relieves pain but has been shown to prevent or reduce IH.

However, it is still possible for a person to have hyperalgesia while taking methadone.

Another medication is buprenorphine, which can help reduce the incidence of hyperalgesia by blocking receptors in the brain and spinal cord.

Ketamine, which also blocks specific receptors, is another option. All these medications, as well as methadone, require close medical supervision.

Another option is a muscle or nerve block, which uses a local anesthetic to numb or delay painful nerve impulses. Sometimes, the treatment of hyperalgesia requires a trial-and-error approach, with frequent adjustments to the medication until a person achieves a reduced pain experience.