Hyperalgesia

What is hyperalgesia?

Hyperalgesia is a symptom that affects how a person feels pain. When you have hyperalgesia, you feel pain in situations where pain is normal, but the level of pain is severe or excessive.

Pain is a normal and healthy part of how your body works. Feeling pain is a warning sign that something is wrong. When a person feels pain, they usually react automatically, trying to stop whatever’s causing the pain. Without the ability to feel pain, people would have no way to tell when to act to protect themselves from even worse injuries.

There are multiple ways that hyperalgesia can happen, and it’s also a symptom of several different conditions. Depending on how and why it happens, this symptom is often treatable.

What is the difference between hyperalgesia vs. allodynia?

Hyperalgesia and allodynia are related issues that are very similar, but there’s one key difference. With hyperalgesia, you feel more pain in response to things that are supposed to hurt. With allodynia, you feel pain in response to things that shouldn’t hurt.

An example of allodynia is feeling pain from clothing touching your skin. Under ordinary circumstances, clothes touching your skin shouldn’t cause pain. Allodynia causes your nervous system to misinterpret signals, mistaking touch signals for pain signals.

An example of hyperalgesia would be feeling intense, excruciating pain when touching a recently burned area of skin. It’s normal to feel pain after a burn, but hyperalgesia causes your nervous system to overreact in response to something painful.

How does hyperalgesia work?

Hyperalgesia changes the way that your body generates and processes pain signals. Those changes usually happen in the following ways:

• You have a lower pain threshold and higher pain sensitivity. Your pain threshold is the point at which something goes from feeling uncomfortable or unpleasant to causing pain. Hyperalgesia makes it easier to reach that threshold.
• You react more strongly. Your pain receptors fire more often than they would under ordinary circumstances. That makes the pain feel much more intense.
• You respond faster. Your body reacts to repeated pain signals by decreasing your response time, causing you to react to pain slightly faster. This happens because your body gives pain signals an unusually high priority, processing and responding to them faster than expected.
• Pain signals don’t stop firing even after the painful event is over. Your pain receptors remain overly sensitive, even when there’s no longer a reason for them to do so. That causes them to keep sending pain signals after they should’ve stopped.

There are two main ways that hyperalgesia happens:

• Primary hyperalgesia. This is when an injury changes how you feel pain in the injured part of your body. An example is feeling much more intense pain when touching an area of sunburned skin.
• Secondary hyperalgesia. This is when the way you feel pain changes in areas that aren’t directly affected by an injury or condition. This happens because of changes in how your nervous system handles pain signals.

Certain forms of hyperalgesia happen in very specific ways or circumstances. Those forms are:

• Referred hyperalgesia.
• Visceral hyperalgesia.

Referred hyperalgesia

Referred pain is when you feel pain near the site of the actual problem, and referred hyperalgesia means that this pain is more intense. It happens because the area where you feel the pain shares nerve connections with the area that actually has the problem.

The effect is like automatically flinching and saying “ouch” when you see someone else trip and fall. Seeing it happen to someone else still activates the same reaction in your brain, even though it isn’t happening to you directly.

Visceral hyperalgesia

Visceral (pronounced “viss-er-al”) hyperalgesia is a form of deep pain that affects organs and structures deeper inside of your body. When this happens, internal pain is more intense. The pain can also cause referred pain in nearby areas, especially when the problem affects an organ or area with few or no nerves inside it that can detect pain.

Migraines are an example of deep pain that happens similarly. Your brain doesn’t have any nerves that can feel pain directly. Instead, your brain interprets the effects, effectively translating other signals into feelings of pain. Migraines also commonly involve hyperalgesia and other pain-related effects, and researchers have uncovered evidence that migraines make a person more susceptible to hyperalgesia elsewhere in the body.

What are the most common causes of hyperalgesia?

Hyperalgesia happens when your body’s pain receptors are too sensitive, causing pain to feel much more intense than it should. There are many possible causes of hyperalgesia, including:

• Burns (including sunburn).
• Bites or stings from insects, reptiles, certain fish species and other animals.
• Cancer.
• Complications from medications (see “Opioid-induced hyperalgesia” below) and medical treatments.
• Diabetes-related nerve damage (neuropathy) that happens with Type 1 or Type 2 diabetes.
• Immune and inflammatory conditions like lupus, multiple sclerosis, etc.
• Infections that attack the nervous system, especially shingles, herpes simplex virus 2 (HSV-2) and similar conditions.
• Migraines.
• Pain disorders like complex regional pain syndrome, central pain syndrome, etc.
• Trauma (any kind of injury, including nerve damage, muscle injuries, broken bones, etc.).

Opioid-induced hyperalgesia

Opioid-induced hyperalgesia (OIH) is a form of secondary hyperalgesia that can happen when taking opioid-based painkiller medications for an extended period. OIH means these medications change how your body handles pain signals, making pain feel much more intense.

OIH isn’t the same as developing a tolerance to these medications. Tolerance is when your body gets used to these medications and develops a kind of immunity to them, meaning they lose their effectiveness.

Experts don’t know exactly how or why OIH happens, but it’s one of the key reasons why experts recommend against long-term use of opioid medications. When a person develops this form of hyperalgesia, providers will usually try to lower the dose of the medication responsible and then stop it entirely.

This is a gradual process because stopping opioid medications suddenly can cause withdrawal and other dangerous side effects. At the same time, providers will also try to find other ways to manage your pain, helping you stay as comfortable as possible without relying on opioid medications.

How is hyperalgesia treated?

Treating hyperalgesia depends on why it happens and what kind of hyperalgesia it is. Treatment can also take many different approaches or even a combination of approaches. Your healthcare provider is the best person to tell you what treatments or approaches they recommend for your specific situation. The information they provide will be the most relevant for you.

Some common forms of treatment for hyperalgesia (with more about them immediately below) include:

• Nerve ablations.
• Nerve blocks.
• Transcutaneous electrical nerve stimulation (TENS).

Medications

Medications that treat pain come in many different forms. Those forms include, but aren’t limited to:

• Pills that you take by mouth.
• Injectable and intravenous (IV) medications.
• Topical medications (creams and patches).

Many different types of medication, including over-the-counter and prescription drugs, can help treat hyperalgesia and related pain problems. The most common types of drugs include:

• Acetaminophen (also known as paracetamol, or under the brand names Tylenol® or Panadol®).
• Antidepressants.
• Anti-seizure medications.
• Local anesthetics (such as lidocaine).
• Nonsteroidal anti-inflammatory drugs (NSAIDs).
• Opioid medications.
• Steroid medications.
• Combination medications, which can involve two or more of the drug types listed above.

Nerve ablations

This treatment method intentionally damages nerves that are sending faulty pain signals. There are two main ways to do these kinds of ablations:

• Radiofrequency (RF) ablation. This form of ablation uses radiofrequency energy to heat the nerves in question, damaging them.
• Chemical denervation. This treatment uses a chemical to block certain functions of nerve cells. Botulinum toxin (commonly known under the trademark name Botox®) is a commonly used medication that can do this.

What can I do at home to treat hyperalgesia?

Hyperalgesia is a problem that can happen with many different conditions, some more serious than others. It’s also an issue that needs a trained, qualified healthcare professional to diagnose and treat it. Because of this, you shouldn’t try to treat it on your own. If a healthcare provider diagnoses you with hyperalgesia, they can offer suggestions and guidance on what you can do to manage this problem at home.

How can hyperalgesia be prevented?

Hyperalgesia happens unpredictably, so it’s impossible to prevent it.

When should hyperalgesia be treated by a doctor or healthcare provider?

Hyperalgesia means you feel pain under circumstances where pain should happen, but the pain is much worse than expected. Some causes of hyperalgesia, especially sunburns or first- and second-degree burns, are very common and will get better as the burn heals. First-degree burns usually don’t need treatment by a healthcare provider, but second-degree burns often need care. You should also see a healthcare provider for burns that affect your head, face or genitals.

Severe pain, especially pain that’s bad enough to disrupt your routine and activities or that lasts for unusually long periods, is often a sign that you should talk to a healthcare provider. They can advise you on what to do and if your pain is a sign you need emergency medical attention.

Long-term effects of severe pain

Pain is a normal part of how your body operates, telling you that something is wrong and you need to act to stop it. When pain is severe or lasts for long periods, it changes the way your nervous system handles pain signals. That can lead to serious conditions or complications like central pain syndrome, which disrupts your body’s normal pain processes and causes pain that’s more severe, difficult to treat or lasts for weeks, months or even years.

Because severe and long-term pain can have such serious effects, it’s important not to ignore that kind of pain. While many people feel embarrassed, guilty or ashamed of getting help for pain, getting that kind of help is exactly what severe pain means you should do.

A note from Cleveland Clinic

Hyperalgesia is a symptom that causes unusually severe pain in situations where feeling pain is normal, but the pain is much more severe than it should be. This condition happens because of disruptions or changes in how your nervous system processes pain. Hyperalgesia is an issue that can happen with many conditions and circumstances. Some of these are minor and will improve on their own, while others are more serious and need medical care.

People who have this aren’t exaggerating or being overly dramatic. The pain they feel is much worse because of problems with how their body processes pain. If you or someone close to you has severe pain, especially pain that seems disproportionately severe, the safest and best move is to seek medical attention. Ignoring severe pain can lead to more serious problems, either with how your body processes pain or with the condition causing the pain in the first place.