Ask the Pharmacist: The mystery pain of small fiber neuropathy

Many people are suffering and don’t know what they have; in time it can lead to bigger problems

Suzy Cohen
Common symptoms of small fiber neuropathy include, internal vibration or restlessness, pins and needles, numbness and muscle aches.

There is neuropathy, and then there is small fiber neuropathy! These conditions are different. Do not dismiss what I’m about to share because you think it’s no different than typical “neuropathy.”

This is a very important article because it will help so many people who are suffering and don’t know what they have. You might very well have small fiber neuropathy (SFN) and if you ignore it, in time it will lead to bigger problems all over your body. But if you read this today and get proper treatment and help, it is very treatable. I want to give you hope, while educating you about the disorder.

Only the small cutaneous (skin) nerves are affected in SFN. The main difference between SFN and typical peripheral neuropathy (PN) is that SFN attacks the “small unmyelinated fibers” hence the name “small fiber neuropathy,” and it begins with sensations in your toes and feet. Most other types of neuropathy have some degree of demyelination occurring, but again, the fibers destroyed in SFN are not myelinated, therefore this does not respond to methylated vitamin B12 like you might suspect.

Here are a few common symptoms of SFN

  • Internal vibration or restlessness
  • Pins and needles
  • Numbness
  • Muscle aches
  • Electric shock sensations in the body
  • Trigeminal neuralgia
  • Redness on the feet termed erythromelalgia
  • GI motility problems
  • Postural orthostatic hypotension (POTS)
  • Bladder problems
  • Dysautonomia

Erythromelalgia is fairly hallmark, and the condition is characterized by episodes of redness, heat, pain, or mild swelling in the feet usually, although it could be the hands or anywhere in the body. It’s usually triggered by raising your body temperature, which means you may exit a nice hot shower, or hot tub, or the steam room and discover one or both feet have turned red, for example. It’s temporary and likely goes away in a few minutes.

Testing for SFN requires a skin biopsy and there are amazing new test kits available now that a physician can order. If your doctor does a regular EMG (electromyography) study on you, it will be normal. That’s the frustrating and confusing part - SFN does not show up on conventional EMG studies or nerve conduction studies.

The causes of SFN vary and may be tied to infections like Lyme disease or shingles, or endocrine conditions like diabetes. Another frequent, but hard to pinpoint cause is autoimmunity. Furthermore, 40 percent of people with fibromyalgia are thought to suffer with some degree of SFN. One more interesting cause for this uncomfortable condition is the use of (or withdrawal from) SSRI antidepressants.

As for treatment, it varies based upon the etiology. We see best effects from intravenous immunoglobulins (IV IG), as well as anti-seizure drugs like pregabalin and gabapentin. I’ve written a more comprehensive article discussing more symptoms and treatments, as well as proper testing. I will know to email it to you if you sign up for my free newsletter. To do that, visit my website

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Suzy Cohen is a registered pharmacist. The information presented here is not intended to treat, cure or diagnose any condition. Visit