Causes of Allodynia: A Rare, Distinct Type of Pain in Fibromyalgia and ME/CFS

Allodynia is a rare type of nerve pain that is triggered by something that wouldn't normally cause pain. That could be the touch of your bedsheets, the seam of a sock, or the warmth coming off of freshly made toast, for example.

This pain type is frequently associated with fibromyalgia. Some research suggests allodynia may be associated with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) as well. Other conditions associated with allodynia include diabetic/peripheral neuropathy, postherpetic neuralgia (nerve damage from shingles), and migraines.

Outside of these conditions, allodynia is a rare symptom. Knowing more about it may help you better communicate with your healthcare providers and, in some cases, empower you to seek a second opinion about your pain.

Types of Allodynia

Allodynia comes in three different forms. It's possible for you to have one, two, or all three kinds. The different forms are:

• Tactile allodynia: This is pain caused by touch. This can include clothing pressing against the skin (especially the tighter parts of clothing, such as waistbands, bra straps, or the elastic part of socks), a hug, or someone touching you lightly on the arm.
• Mechanical allodynia: This type of pain caused by movement across the skin. This can be a towel as you dry yourself off, bedsheets brushing against you, or even the air from a fan moving over your skin.
• Thermal (temperature-related) allodynia: This pain is caused by heat or cold that is not extreme enough to cause damage to your tissues. Your hands and feet may burn if they get chilled, or getting too hot may make them ache.

Note that you should talk to your healthcare provider if your hands and feet turn blue when they're cold. This may be a symptom of a different condition called Raynaud's syndrome, which can lead to tissue damage.

Allodynia is different from hyperalgesia, which is the mechanism that "turns up the volume" on pain in these conditions. Hyperalgesia takes your pain and makes it worse, while allodynia is an actual type of pain.

Causes

Allodynia is thought to be a hypersensitive reaction to stimuli. Research suggests it may result from central sensitization, which is believed to be an underlying mechanism of fibromyalgia, ME/CFS, and several other conditions. "Central" indicates the central nervous system (brain and spinal cord) and "sensitization" means that it's become extra sensitive.

In some conditions, research suggests allodynia may be caused by peripheral sensitization, which involves the nerves outside of your central nervous system.

The pain signals of allodynia come from specialized nerves called nociceptors. The job of nociceptors is to sense information about things like temperature and painful stimuli on the skin.

Most nerves have to send signals to the brain and wait for the brain to send a signal back before they respond. Nociceptors don't have to do that—they react immediately based on what they detect. This allows you to pull your hand away from something hot before you get burned, often before you consciously perceive the heat.

When these nerves become sensitized, they start interpreting all kinds of sensations as pain. Again, this is real pain that has just as much of an impact on you as any other source of pain.

Treatment

So far, it's unknown whether allodynia can be treated the same in every condition. Most of the common drug treatments for illnesses that involve this symptom can help alleviate allodynia and other types of pain. These include:

• Lyrica (pregabalin): Often prescribed for fibromyalgia, neuropathy, and postherpetic neuralgia, and sometimes used off-label for ME/CFS
• Neurontin (gabapentin): Often prescribed for postherpetic neuralgia and used off-label for fibromyalgia and neuropathy
• Tricyclic antidepressants such as amitriptyline: Often used off-label for fibromyalgia, ME/CFS, neuropathy, postherpetic neuralgia, and migraine

Some people also get some relief with topical painkillers, such as lidocaine and menthol-based products like BioFreeze and Tiger Balm. While testing on humans hasn't yet been done, numerous animal studies support the use of ingested and topical cannabidiol (CBD), a hemp product that doesn't create a "high," for allodynia.

Most complementary and alternative treatments haven't been studied specifically for their effect on allodynia, but they have been investigated for central sensitization. As that's the suspected underlying mechanism of allodynia, it's possible that these treatments may be helpful:

• Acupuncture: A 2019 review of studies on acupuncture for central sensitization concluded that the treatment can alleviate pain symptoms, including allodynia.
• Mindfulness practices: Research published in 2020 suggests that practices involving mindfulness, including meditation and mindfulness-based stress reduction, are effective for alleviating pain in conditions that involve central sensitization.
• Cognitive behavioral therapy (CBT): A psychological approach aimed at helping you make positive mental changes that impact your health, research has long shown that it may be of benefit in central sensitization.

Lifestyle Changes

Allodynia can make your life difficult. Something as simple as wearing a shirt may become painful, or even agonizing. Many people who have allodynia find that they need to tailor their wardrobes to reduce the impact of this pain.

Thermal allodynia can play a role in another symptom—temperature sensitivity. To manage it, you may need to do things like dressing in layers or moving your workstation away from vents that blast you with hot or cold air. You may have to learn how to compensate for both cold and hot conditions.

Dietary Management

Some research has suggested that compounds in certain foods may alleviate neuropathic pain and the allodynia associated with it. While it's too early to say for sure, it may be that eating these foods or getting the active compounds via supplements could help ease your pain.

A Word From Verywell

The conditions associated with allodynia are often chronic and difficult to treat. You may not ever be completely free from the pain, but by working with your healthcare provider and making appropriate lifestyle changes, you may be able to minimize its impact on your life.

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