Allodynia is a type of neuropathic pain. Someone who has allodynia feels unexpected pain from non-painful stimuli, like from a light touch or when brushing their hair.
Some people feel extreme pain from something minor, such as a paper cut. Feeling increased pain or being hypersensitive to mild pain is called hyperalgesia.
Allodynia is different from hyperalgesia, although a person may have both. In allodynia, a person can feel pain with a stimulus that does not usually cause pain, such as the brush of a feather.
Experts do not know precisely why allodynia happens, but it is most likely a symptom of a nerve condition. One theory is that certain nerve fibers are crossed, leading to unusual reactions.
Here, learn about the symptoms of allodynia, why it happens, and how to manage it.
The main symptom of allodynia is pain.
Pain is a protective mechanism that tells a person to stop doing something harmful. For instance, a pain response causes a person to pull their hand away from a hot stove, preventing a severe burn.
For people with allodynia, pain occurs even though nothing harmful is causing it. A light touch, such as washing the face, a few hairs touching the skin, or a breath of air may be painful.
According to the American Migraine Foundation, allodynia can feel like having sunburn all over the body.
Symptoms can range from mild to severe, and the sensations can also vary. Some people may feel a burning sensation, while others feel an ache or squeezing pain.
Allodynia can limit a person’s activities and affect their quality of life. Symptoms may also worsen over time.
- Thermal allodynia: Pain occurs when there is a mild change of temperature on the skin. For example, a few drops of cold water on the skin may be painful.
- Dynamic or mechanical allodynia: Movement — such as bedsheets pulled across the skin — may be painful.
- Static or tactile allodynia: A light touch or pressure on the skin, such as a light tap on the shoulder, causes pain.
People may also describe it according to the part of the body where it occurs. For instance, cutaneous allodynia affects the skin.
Some people may only have one type of allodynia. Others may have several types.
The pain is related to nerves inside the body. It can affect different parts of the body depending on the type of allodynia and the underlying cause.
Experts do not know precisely why allodynia happens, but it is a type of neuropathic pain that involves sensitization.
Sensitization occurs when a nerve is damaged, and the nerves become hypersensitive. This can cause the nerve endings to release higher quantities of neurotransmitters, leading to nerve inflammation. Allodynia or hyperalgesia can result.
Nerve damage can result from a health condition or injury or for no apparent reason. It can occur in the peripheral nervous system and lead to sensitization in the central nervous system.
Having one of the following medical conditions may also increase a person’s risk of developing allodynia.
Migraine can cause debilitating headache and other symptoms, such as sensitivity to sound and light. At least
The authors of one
Fibromyalgia causes widespread pain in the body. There may be a link between allodynia and fibromyalgia.
Diabetes can cause nerve damage and increase the risk of nerve pain, including allodynia.
Nerve growth factor (NGF) is essential to the nervous system, and some experts have suggested that diabetes can lower NGF levels. A 2017 rodent study linked low levels of NGF with both hyperalgesia and allodynia.
Complex regional pain syndrome
Complex regional pain syndrome (CRPS) involves
Having chemotherapy, surgery, or a traumatic injury can also increase the risk of having allodynia.
No single test can diagnose allodynia.
Instead, a doctor will:
- perform a physical exam
- take a medical history
- review a person’s symptoms
They may ask questions such as:
- When did the symptoms start?
- Are they getting worse?
- Do they come and go?
- How would you describe this pain?
- Have you taken any medications for it?
- What makes it better, and what makes it worse?
- Do you feel the pain with touch, heat, movement, or something else?
During a physical examination, the doctor may:
- deliver a light touch to the area
- look for skin changes and other symptoms
- use the back of a cold device, such as a spoon, to assess the reaction to temperature
- test for strength and reflexes
As well as the affected area, the doctor will assess other areas and both sides of the body for comparison. They may also do tests to rule out other possible conditions before diagnosing allodynia.
Anyone experiencing unexplained or unexpected pain should seek medical advice.
Complementary and lifestyle approaches may help treat allodynia. The precise approach will depend on the cause of allodynia, the individual, and how symptoms affect them.
Lifestyle choices that may help include:
- light exercise
- following a varied diet
- getting enough sleep
- quitting smoking, as
research showssmokers are more likely to experience chronic pain than nonsmokers
Lifestyle will not cure allodynia but can enhance people’s overall mental and physical health. This may make allodynia easier to live with.
People can also:
- identify pain triggers and take measures to avoid them, where possible
- choose fabrics, hair brushes, and other items that are less likely to cause pain
- find ways to manage stress, as stress can worsen the symptoms of pain
There is no cure for allodynia, but some treatments can reduce pain.
Here are some
- pregabalin tablets
- anticonvulsant tablets, including gabapentin
- anti-depressants can help some people
- topical pain medications containing lidocaine, a local anesthetic
- topical creams containing menthol or capsaicin, although these may trigger thermal allodynia
- other topical treatments containing gabapentin, ketamine, salicylates, and other ingredients
A doctor may also recommend:
- counseling or psychotherapy to help identify ways to cope with allodynia
- physical therapy, biofeedback, and exposure therapy
- nerve blocks, which may provide relief lasting from
several hoursto several months
- nerve stimulators, in which a doctor carries out minor surgery to implant a device
- surgery can be a permanent solution if a specific nerve area is causing allodynia
Treating an underlying condition that is causing allodynia may also help. For example, taking medication to prevent migraine can reduce the risk of allodynia symptoms. Managing blood sugar levels can reduce the risk of diabetic neuropathy.
Allodynia is not life threatening, but it can make daily life challenging. It can also lead to anxiety and other mental health conditions.
The outlook for people with allodynia varies depending on the severity of the symptoms and any underlying conditions, such as diabetes or migraine.
Here are the answers to some questions people often ask about allodynia.
What is the difference between allodynia and hyperalgesia?
Hyperalgesia and allodynia are
What triggers allodynia?
People with shingles, diabetic neuropathy, fibromyalgia, and migraine often experience allodynia, but it can also occur after an injury or surgery.
Can allodynia go away without treatment?
Treatment for an underlying condition
People with allodynia experience pain that seems unrelated to the cause, or stimulus. It appears to result from a problem with the nervous system.
It can happen for various reasons, including an injury, surgery, migraine, fibromyalgia, or as a result of nerve damage due to diabetes.
Various oral and topical pain medications can help manage it. some non-drug and lifestyle measures may also help.