Foot neuropathy happens when nerves in the feet become damaged, and diabetes is by far the most common cause. About 36% of people with diabetes develop peripheral neuropathy, with the feet typically affected first because the longest nerves in the body are the most vulnerable. But diabetes is only one of many possible triggers. Alcohol use, vitamin deficiencies, chemotherapy, infections, and autoimmune conditions can all damage the nerves that supply sensation and movement to your feet.
Diabetes and High Blood Sugar
Persistently elevated blood sugar is the single biggest driver of foot neuropathy worldwide. The damage isn’t just from sugar sitting in the bloodstream. Excess glucose gets funneled into an alternative chemical pathway inside nerve cells, where it’s converted into sorbitol. As sorbitol builds up, it disrupts the fluid balance inside the cell, forcing out compounds the nerve needs to function normally. Over time, this process weakens the structural integrity of the nerve.
High blood sugar also floods nerve cells with unstable molecules called reactive oxygen species. These molecules accumulate over months and years, gradually causing irreversible damage to both the nerve fibers themselves and the tiny blood vessels that supply them with oxygen. The combination of metabolic stress and impaired blood flow leads to demyelination, where the protective insulation around nerve fibers breaks down, and eventually to nerve cell death. This is why people with poorly controlled blood sugar for years often notice numbness or tingling in their toes before symptoms appear anywhere else.
The prevalence of diabetic neuropathy is notably higher in developing countries (39%) compared to developed ones (25%), likely reflecting differences in access to blood sugar management and early screening.
Vitamin B12 and Other Nutritional Deficiencies
Your nerves rely on a protective coating called myelin to transmit signals quickly and accurately. Vitamin B12 is essential for building and maintaining that coating. Without enough B12, the body produces abnormal fatty acids that get incorporated into myelin, leading to faulty insulation or outright breakdown of the nerve’s protective layer. Levels below about 200 pg/mL are associated with a significantly increased risk of neuropathy, roughly 1.5 times the risk compared to people with adequate levels.
B12 deficiency is particularly common in older adults, people who take long-term acid-reducing medications, and those who follow strict vegetarian or vegan diets without supplementation. Deficiencies in other B vitamins, particularly B6 and B1 (thiamine), can also contribute. Interestingly, too much B6 from high-dose supplements can itself cause neuropathy, so balance matters more than simply loading up.
Alcohol Use
Heavy, sustained drinking is one of the more common non-diabetic causes of foot neuropathy. Research suggests the threshold is roughly 300 ml of spirits (about 10 ounces) per day over several years. One study found that 41% of patients who consumed more than 15 kg of alcohol per kilogram of body weight over their lifetime met criteria for alcoholic neuropathy.
The damage comes from two directions. Alcohol is directly toxic to nerve fibers, but heavy drinkers also tend to have poor nutritional intake, especially of thiamine and other B vitamins. This means the nerves are hit with a chemical toxin while simultaneously being deprived of the nutrients they need to repair themselves. The result is a burning, painful numbness that typically starts in the soles of the feet and works its way upward.
Chemotherapy and Medications
Certain cancer treatments are well known for causing foot neuropathy as a side effect. Taxane-based chemotherapy drugs work by disrupting the internal scaffolding of cancer cells, but they also interfere with that same scaffolding in nerve cells. This disruption can trigger abnormal calcium release inside neurons, essentially overwhelming them with chemical signals and leading to damage in the sensory nerves of the feet and hands.
Chemotherapy isn’t the only medication that can cause problems. Several antibiotics also carry neuropathy risk. Fluoroquinolones, a commonly prescribed class of antibiotics, can cause burning pain that starts in the soles of the feet and spreads upward. Isoniazid, used to treat tuberculosis, causes neuropathy by interfering with vitamin B6 metabolism. Linezolid, another antibiotic, produces a similar pattern of burning foot pain that worsens with continued use. In most medication-related cases, symptoms improve after the drug is stopped, though recovery can take months.
Infections That Target Nerves
Several infections can damage the peripheral nerves directly. HIV is among the most significant: between 30% and 50% of people with advanced HIV infection develop a distal symmetric polyneuropathy, which typically shows up as numbness and tingling in a “stocking” pattern covering the feet and lower legs.
Hepatitis C can trigger neuropathy through an indirect route. The virus sometimes causes the immune system to produce abnormal protein clusters called cryoglobulins, which damage small blood vessels supplying the nerves. Shingles, caused by the reactivation of the varicella-zoster virus, can produce nerve pain in the legs and feet when the virus reactivates in the lumbar nerve root ganglia near the lower spine, though this is less common than shingles affecting the torso or face. Leprosy, still prevalent in parts of the world, causes bilateral symmetric neuropathy in the feet during its later stages.
Autoimmune and Inflammatory Conditions
Sometimes the immune system itself attacks the peripheral nerves. In Guillain-Barré syndrome, the attack comes on rapidly, often following an infection, and can cause weakness and numbness that starts in the feet and ascends. A related condition called chronic inflammatory demyelinating polyneuropathy (CIDP) follows the same basic pattern but develops more slowly, over weeks to months rather than days.
In both conditions, the immune system produces antibodies that target components of the nerve’s myelin sheath or the nodes along the nerve fiber where electrical signals jump from one segment to the next. This strips the insulation from the nerve, slowing or blocking signal transmission. CIDP is diagnosed through a combination of clinical symptoms, elevated protein levels in spinal fluid, and nerve conduction testing that shows characteristic patterns of slowed signaling.
Other Contributing Factors
Kidney disease allows toxins to accumulate in the blood that would normally be filtered out, and these toxins can damage peripheral nerves over time. Thyroid disorders, particularly an underactive thyroid, can cause fluid retention that compresses nerves. Physical causes like repetitive pressure or injury to the feet can damage nerves locally rather than systemically.
In roughly 30% of neuropathy cases, no clear cause is identified despite thorough testing. This is called idiopathic neuropathy, and it tends to progress slowly. Even without a definitive diagnosis, treatment can still target symptom relief and preventing further nerve loss.
How Foot Neuropathy Gets Diagnosed
If you’re experiencing numbness, tingling, or burning in your feet, the diagnostic process typically starts with blood work to check for diabetes, vitamin deficiencies, thyroid problems, and markers of infection or inflammation. Nerve conduction studies and electromyography (EMG) can measure how well electrical signals travel through the larger nerve fibers in your feet and legs.
One important limitation: standard nerve conduction testing can only evaluate large nerve fibers. It cannot detect small fiber neuropathy, which is the type responsible for burning pain and temperature sensitivity. If your symptoms are classic for neuropathy but nerve conduction results come back normal, a skin biopsy or autonomic reflex testing may be needed to confirm small fiber involvement. This distinction matters because small fiber neuropathy is often the earliest stage of diabetic nerve damage and can be missed without specific testing.