Allodynia is an uncommon symptom that can result from several nerve-related conditions.

When you’re experiencing it, you feel pain from stimuli that don’t normally cause pain. For example, lightly touching your skin or brushing your hair might feel painful.

Allodynia is rare, though it’s common in people with neuropathic pain. According to a 2014 study, 15 to 50 percent of people with neuropathic pain experience allodynia.

There are three types of allodynia:

  • Tactile (static) allodynia: a severe sensation of pain
  • Thermal allodynia: a change in temperature that causes pain, such as a small drop of cold water that results in significant discomfort
  • Mechanical (dynamic) allodynia: a painful sensation that occurs when a person is affected by typically harmless stimuli moving across the skin, such as light touch

“Allodynia is not itself a condition that is diagnosed — it is a symptom that can be associated with certain types of pain,” says Vivianne Tawfik, MD, PhD, a board certified anesthesiologist and pain medicine specialist with Stanford Hospital and Clinics.

According to Medhat Mikhael, MD, medical director of the nonoperative program at Spine Health Center at MemorialCare Orange Coast Medical Center in California, allodynia can result from a “simple touch like a blanket over the painful area or tight cloth.”

To ease allodynia, you will need to treat the underlying cause.

The main symptom of allodynia is pain from stimuli that don’t usually cause pain.

In some cases, you might find hot or cold temperatures painful. You might find gentle pressure on your skin painful. You might feel pain in response to a brushing sensation or other movement along your skin or hair.

Depending on the underlying cause of your allodynia, you might experience other symptoms too.

For example, if it’s caused by fibromyalgia, you might also experience:

If it’s linked to migraine, you might also experience:

  • painful headaches
  • increased sensitivity to light or sounds
  • changes in your vision
  • nausea

Some underlying conditions and lifestyle factors can cause allodynia. It may be linked to:

A 2018 clinical trial indicated that PIEZO2, a gene that controls the sense of touch, may contribute to tactile allodynia.

Fibromyalgia

Fibromyalgia is a disorder in which you feel muscle and joint pain throughout your body that isn’t related to an injury or a condition, such as arthritis.

Instead, it seems to be linked to the way your brain processes pain signals from your body. It’s still something of a medical mystery. Scientists don’t quite understand its roots, but it tends to run in families.

Certain viruses, stress, or trauma might also trigger fibromyalgia.

Migraine headaches

Migraine is a condition that causes intense pain. Changes in nerve signals and chemical activity in your brain trigger migraine headaches. In some cases, these changes can cause allodynia.

Peripheral neuropathy

Peripheral neuropathy happens when the nerves that connect your body to your spinal cord and brain become damaged or destroyed. It can result from several conditions, such as diabetes.

Chickenpox, shingles, and postherpetic neuralgia

Shingles is a disease caused by the varicella-zoster virus, which also causes chickenpox.

Postherpetic neuralgia is the most common complication of shingles. Heightened sensitivity to touch is a potential symptom of postherpetic neuralgia.

A 2018 study noted that tactile allodynia was common in people with shingles.

“Any nerve damage, however central or peripheral, can be associated with allodynia,” Mikhael says. “The shingle virus causes damage to the affected nerve.”

Opioid use

Opioid use can induce hyperalgesia, a condition involving amplified pain that can lead to allodynia, according to a 2017 review.

“Opioid exposure causes changes in the central nervous system, which can also lead to an intensification of other sensations of pain, including but not limited to allodynia,” says Seth A. Waldman, MD, MBE, director of the division of pain management at Hospital for Special Surgery.

If a person regularly uses opioids, they may feel they need higher doses to alleviate the pain. Mikhael says this can increase the risk of developing allodynia.

“Excessive use of opioids can cause a paradoxical effect, so instead of the narcotics alleviating pain, it causes you to have even more pain and sensitivity,” he says.

Mikhael notes that several factors contribute to the link between opioid use and allodynia, including:

  • brain disorders
  • differences in pain processing
  • malfunction of opioid receptors

Chemotherapy

Mikhael says chemotherapy can have a toxic effect on nerves, which can result in peripheral nerve damage. Sometimes, this nerve damage causes allodynia.

A 2019 study in mice indicated that chemotherapy could induce mechanical allodynia.

A 2019 paper pointed to research suggesting that mechanical or thermal allodynia frequently occurred in people experiencing chemotherapy-induced peripheral neuropathy (CIPN).

Diet and nutrition

Mikhael notes that vitamin deficiencies can play a role in the development of allodynia. It may also develop as a result of diabetes.

“Vitamin deficiency can cause nerve damage and consequently develop allodynia,” he says. “Correcting and treating deficiencies in vitamins B12, E, B6, folic acid, copper, and B1 are very important. Foods high in fat and sugar tend to aggravate these symptoms even more.”

A 2017 study in mice suggested that high fat diets and obesity were linked to allodynia.

Trauma

Mikhael says even seemingly minor trauma, like spraining an ankle while playing sports, can result in allodynia.

“The trauma can cause an abnormal response and sensitization of the central nervous system,” he says. “Any crushing injury to the extremity or extreme injury like a spinal cord injury can cause allodynia.”

A small 2021 study involving 30 people with post-traumatic headaches suggested 79 percent of participants experienced hypersensitivity. Of those people, 54 percent were affected by tactile and light hypersensitivity.

If you notice your skin has become more sensitive to touch than normal, you can run a self-test to determine whether you may have symptoms of allodynia. To do this:

  1. Brush a dry cotton pad on your skin.
  2. Apply a hot or cold compress.

If you experience a painful tingling feeling in response to any of these stimuli, you might have allodynia. It’s important to make an appointment with a doctor to confirm this.

Your doctor will go over any underlying conditions, such as diabetes, and ask you about symptoms.

“When discussing with your doctor, come prepared with a description of your pain, as accurate as possible,” says Amanda Persaud, MD, a neurologist with Northwell Health. “The description of the quality of pain is very important when deciphering whether pain is neuropathic, like allodynia.”

Persaud suggests using these terms to describe symptoms, as applicable:

  • burning
  • throbbing
  • constant
  • intermittent
  • radiating

Tawfik says your doctor will likely run a similar test to your self-examination.

Once a doctor has determined allodynic pain, they can run further tests to find the underlying cause, says William Caldwell, DO, director of the Center for Pain Management at Stony Brook Medicine.

Additional testing for the underlying cause may include:

If your doctor suspects you might have diabetes, they will likely order blood tests to measure your level of blood glucose. They might also order blood tests to check for other possible causes of your symptoms, such as thyroid disease or infection.

Mikhael notes that treatment will depend on the underlying cause of your allodynia. Treatments may include:

Capsaicin products are commonly used to reduce pain from conditions like arthritis or muscle strains. They can include patches, creams, gels, and ointments.

“Surgery could be an option in cases of nerve entrapment or [central or peripheral] compression,” Mikhael says. “The implantation of neuromodulators can be very helpful in treatment.”

Still, the best course of treatment is often managing the trigger.

“The focus in the treatment of allodynia needs to be on treating the causative condition,” says Lev Kalika, doctor of chiropractic and owner of New York Dynamic Neuromuscular Rehabilitation & Physical Therapy in New York City.

For example, managing diabetes can reduce allodynic pain, while cognitive behavioral therapy can help you cope better with pain and reduce triggers in your lifestyle.

Allodynia is painful, so it’s understandable people want to prevent it, particularly if they have risk factors.

While Caldwell says that allodynia is not entirely preventable, people with underlying conditions connected to allodynia can reduce their risk of it.

“Allodynic pain can develop with uncontrolled diabetes, and strict glycemic control can help to prevent the development of neuropathic pain,” Caldwell says.

“Allodynic pain can often occur after post-herpetic neuralgia [shingles] or trigeminal neuralgia, which are commonly triggered by stress or anxiety,” he says.

Better management of these can lessen the risk of flares of the underlying disease process, he notes.

Tawfik stresses the importance of seeing a doctor as quickly as possible if you’re experiencing abnormal pain.

“Any time someone has pain that outlasts its usefulness or expected post-injury trajectory, a person should see their doctor,” she says.

Caldwell says the underlying cause of allodynia will often determine people’s outlook.

“In many instances, time and proper treatment can decrease or eliminate pain,” he says. “Sometimes more advanced interventional pain procedures are needed to control the pain long term.”

Caldwell also notes allodynia can be chronic or come back, particularly if the underlying cause is not well managed.