Diabetes is the most common cause of foot neuropathy, but it accounts for only about a third of all cases. Another third stems from identifiable non-diabetic causes, and roughly one in three patients leaves their doctor’s office without a definitive diagnosis even after extensive testing. The list of potential triggers is long, ranging from vitamin deficiencies and alcohol use to autoimmune diseases, inherited conditions, and toxic exposures.
Vitamin B12 and Other Nutritional Deficiencies
Vitamin B12 plays a critical role in building and maintaining the protective coating around your nerves, called the myelin sheath. Without enough B12, your body produces abnormal fatty acids that degrade this coating, leaving nerves exposed and unable to transmit signals properly. The result is typically a slowly progressive sensory neuropathy that starts in the feet with numbness, tingling, or burning pain.
A systematic review of 32 studies found that neuropathy risk increased significantly when B12 levels dropped below about 205 ng/L. Levels under 148 pg/mL are considered severely deficient. Common reasons for low B12 include strict vegetarian or vegan diets, long-term use of acid-reducing medications, and conditions that impair nutrient absorption like celiac disease or Crohn’s disease. Other B vitamins, particularly B1 (thiamine), B6, and folate, can also contribute to nerve damage when chronically low.
Alcohol Use
Chronic alcohol use damages nerves through two separate pathways. The first is direct toxicity: ethanol and its breakdown product, acetaldehyde, generate harmful molecules that damage nerve proteins, fats, and DNA. Research in both animals and humans shows a clear dose-dependent relationship, meaning the more alcohol consumed over a lifetime, the worse the nerve damage tends to be. Ethanol also disrupts the internal transport system within nerve fibers, slowing the movement of essential materials along the length of the nerve.
The second pathway is nutritional. Alcohol interferes with thiamine absorption in the gut, depletes the liver’s thiamine stores, and blocks the conversion of thiamine into its active form. People who drink heavily also tend to eat poorly, compounding the deficiency. These two forms of damage look slightly different: alcohol’s direct toxicity tends to cause a slowly worsening, sensation-dominant neuropathy, while thiamine deficiency alone produces a more acute, motor-dominant pattern affecting both sensation and muscle strength.
Chemotherapy and Medication Side Effects
Chemotherapy-induced neuropathy is one of the most common non-diabetic causes, affecting anywhere from 11% to 87% of patients depending on the drug. The six main drug classes known to damage peripheral nerves include platinum-based agents, taxanes, vinca alkaloids, epothilones, proteasome inhibitors, and immunomodulatory drugs. Platinum-based agents and taxanes are the most neurotoxic.
The timing varies. Oxaliplatin triggers acute neuropathy in 65% to 98% of patients within hours of infusion, lasting up to a week. Taxane-related symptoms can start days after the first dose. Most other chemotherapy drugs cause symptoms that emerge weeks or months after treatment ends, with severity proportional to the cumulative dose. The most frustrating aspect for many patients is how long it lasts: neuropathy from platinum agents and taxanes can persist for years after completing treatment, and in some cases becomes permanent.
Beyond chemotherapy, other medications that can cause neuropathy include certain antibiotics (particularly fluoroquinolones and nitrofurantoin), some heart and blood pressure medications, and anticonvulsants.
Autoimmune and Inflammatory Diseases
Several autoimmune conditions attack the peripheral nervous system. Sjögren’s syndrome, best known for causing dry eyes and dry mouth, is the autoimmune disease most strongly linked to neuropathy. Up to 60% of Sjögren’s patients develop some form of peripheral nerve involvement, and up to 30% of patients diagnosed with small fiber neuropathy (the type that causes burning feet with normal nerve conduction tests) turn out to have Sjögren’s.
Systemic vasculitis, which inflames blood vessels supplying the nerves, causes neuropathy in up to 70% of affected patients. Lupus leads to neuropathy in roughly 15% of cases. In Sjögren’s-related neuropathy, the immune system sends inflammatory cells to invade the nerve cell bodies near the spinal cord, directly damaging them. Guillain-Barré syndrome and its chronic counterpart, CIDP, are purely neurological autoimmune conditions where the immune system attacks the nerve’s myelin coating, causing progressive weakness and sensory loss that often begins in the feet and moves upward.
Inherited Conditions
Charcot-Marie-Tooth disease (CMT) is the most common inherited neuropathy, linked to mutations in more than 100 different genes. The most prevalent form, CMT1A, results from a duplication of a gene responsible for producing a protein in the myelin sheath. When too much of this protein is made, the myelin becomes abnormal and nerves conduct signals poorly.
Muscle weakness from CMT typically starts in the feet and lower legs during the teen years or early adulthood, though symptoms can appear at any age. CMT1A often begins in childhood and worsens slowly. CMT4, a rarer form, usually causes leg weakness in childhood, and many affected individuals lose the ability to walk by their teen years. The X-linked form (CMTX) tends to cause moderate to severe symptoms in boys starting in late childhood, while girls may have milder or no symptoms. High arches, hammertoes, and difficulty with balance are hallmark early signs.
Kidney and Liver Disease
As kidney function declines, waste products that the kidneys normally filter out accumulate in the blood and gradually poison peripheral nerves. This process, called uremic neuropathy, is estimated to affect 60% to 100% of patients on dialysis. It typically presents as a symmetrical process with greater involvement in the legs than the arms, creeping up over months with numbness, prickling sensations, and eventually weakness. Liver disease, particularly advanced cirrhosis, can cause neuropathy through similar toxic accumulation and associated nutritional deficiencies.
Infections
Several infections can damage peripheral nerves. HIV can cause neuropathy both directly and through the medications used to treat it. Shingles, caused by reactivation of the chickenpox virus, frequently leaves behind a painful neuropathy called postherpetic neuralgia in the affected area. Hepatitis C is associated with neuropathy in a significant minority of patients. Lyme disease, when it progresses to involve the nervous system, can cause nerve inflammation and radiculopathy, a pattern especially well documented in European cases where a painful condition called Bannwarth’s syndrome involves nerve roots and produces radiating pain.
Heavy Metal and Toxic Exposures
Lead, arsenic, and mercury each produce distinct patterns of nerve damage. Lead poisoning classically causes extensor weakness, leading to wrist drop and foot drop, with relatively mild sensory symptoms. You might also see a blue-gray line along the gums, abdominal pain, and anemia. While the systemic symptoms often reverse with treatment, neurological damage can persist.
Arsenic exposure in its chronic form causes numbness and tingling, often accompanied by characteristic skin changes, abdominal symptoms, and low blood counts. Subacute arsenic poisoning can mimic Guillain-Barré syndrome closely enough to confuse clinicians. Mercury exposure leads to peripheral neuropathy in about 50% of affected individuals as a long-term consequence, with weakness, numbness, diminished reflexes, and sensory loss.
Nerve Compression in the Foot
Not all foot neuropathy is systemic. Tarsal tunnel syndrome occurs when the main nerve running behind the inner ankle bone gets compressed as it passes through a narrow bony channel covered by a thick band of tissue. This produces pain, tingling, and numbness along the sole of the foot, typically on one side. It is essentially the foot’s version of carpal tunnel syndrome in the wrist.
The key distinction from systemic neuropathy is that tarsal tunnel syndrome is usually unilateral or clearly asymmetric. If symptoms are bilateral and symmetric, a systemic cause like polyneuropathy is more likely. Nerve conduction studies and electromyography can confirm whether the compression is localized to the tarsal tunnel or whether a broader neurological condition is responsible. Disc problems in the lower spine, particularly at the S1 level, can also mimic foot neuropathy with patchy sensory symptoms along the sole.
When No Cause Is Found
Even after thorough evaluation, about one-third of neuropathy patients receive a diagnosis of chronic idiopathic axonal polyneuropathy, meaning no identifiable cause. This affects an estimated 5 to 8 million Americans. The condition typically involves slowly progressive sensory symptoms in the feet, and while the label “idiopathic” can feel unsatisfying, it does help guide expectations: most cases follow a gradual course, and treatment focuses on managing symptoms like pain and balance problems rather than targeting an underlying disease.