Foot neuropathy happens when the peripheral nerves carrying signals between your feet and your brain become damaged, leading to numbness, tingling, burning, or pain. Diabetes is the single most common cause, but dozens of other conditions can trigger the same kind of nerve damage, from vitamin deficiencies to chemotherapy to chronic alcohol use. In about 20% to 25% of cases, doctors never identify a definitive cause even after thorough testing.
Diabetes and High Blood Sugar
Persistently elevated blood sugar is the leading driver of foot neuropathy worldwide. The damage unfolds through several overlapping pathways. Excess glucose in the blood gets converted into byproducts like sorbitol and fructose, which promote oxidative damage inside nerve cells. High blood sugar also activates inflammatory signaling cascades and accelerates the formation of compounds that stiffen and injure small blood vessels supplying the nerves.
The cells that insulate and protect your nerve fibers are especially vulnerable because they absorb glucose more readily than other cells. When those protective cells malfunction, the nerve fibers they wrap around lose structural support and begin to degrade. At the same time, disrupted insulin signaling slows your body’s ability to repair damaged nerve fibers and accelerates cell death in already injured tissue. Abnormal cholesterol and triglyceride levels, common alongside diabetes, compound the problem by triggering many of the same destructive pathways.
This is why blood sugar control matters so much. The damage is gradual, often building over years before symptoms appear, and it typically starts in the longest nerves first, which is why the feet are almost always affected before the hands.
Vitamin B12 and Other Nutritional Deficiencies
Vitamin B12 plays a direct role in maintaining the insulating coating (myelin) around nerve fibers. When B12 drops too low, that coating breaks down, slowing or distorting the electrical signals your nerves carry. The standard clinical cutoff for B12 deficiency is relatively low, but research from a Neurology study found that optimal nerve function may require B12 levels roughly 2.7 times higher than that threshold. Older adults with levels below about 390 to 410 pmol/L showed measurably slower nerve conduction and faster cognitive decline, suggesting the bar for “enough B12” is higher than many people assume.
Other nutritional gaps can cause or worsen foot neuropathy too. Deficiencies in vitamins B1, B6, and E, as well as copper, all play roles in nerve health. People who have had weight-loss surgery, follow highly restrictive diets, or have absorption disorders like celiac disease are at higher risk.
Chemotherapy and Other Medications
Certain cancer drugs are well-known causes of foot neuropathy. Taxanes and platinum-based agents carry the highest risk, though vinca alkaloids, thalidomide, and bortezomib can all damage peripheral nerves. The pattern is distinctive: numbness, tingling, and pain in a “glove and stocking” distribution, affecting the hands and feet symmetrically.
The numbers are striking. About 68% of people who receive neurotoxic chemotherapy have neuropathy symptoms one month after finishing treatment. At three months, that figure is still around 60%. By six months, roughly 30% of patients continue to experience symptoms. For some, the nerve damage is permanent.
Beyond chemotherapy, several other medications can contribute. Certain antibiotics, anticonvulsants, and heart medications have been linked to peripheral nerve damage, particularly with long-term use.
Chronic Alcohol Use
Heavy, long-term alcohol consumption damages foot nerves through a two-pronged attack. Alcohol itself appears to be directly toxic to nerve fibers. On top of that, chronic drinking disrupts the absorption and metabolism of B vitamins and other nutrients essential for nerve health, compounding the damage. Separating these two mechanisms in any individual case is difficult, and both are likely at work simultaneously in most people with alcohol-related neuropathy.
Infections That Damage Nerves
Several infections can trigger foot neuropathy, each through a different mechanism.
HIV does not directly infect nerve cells. Instead, it dysregulates immune cells and causes them to overproduce inflammatory chemicals that damage nerves indirectly. Researchers have also found evidence of mitochondrial damage (the energy-producing structures inside cells) specifically in the longest nerve fibers, which explains why the feet are affected first. Some older HIV medications themselves cause neuropathy, creating a double risk.
Shingles occurs when the varicella-zoster virus, dormant in nerve cell clusters since a childhood chickenpox infection, reactivates. The reactivation directly inflames and damages nerve tissue, sometimes causing persistent burning pain in the affected area that can last months or years after the rash clears.
Lyme disease, caused by bacteria transmitted through tick bites, damages nerves through inflammation and injury to the small blood vessels that supply them. The resulting nerve damage can be scattered across multiple sites rather than following the typical feet-first pattern.
Autoimmune and Inflammatory Conditions
Sometimes the immune system turns against the body’s own nerve insulation. In Guillain-Barré syndrome (GBS), this attack comes on rapidly and can cause weakness and sensory changes in the feet and legs within days. In chronic inflammatory demyelinating polyneuropathy (CIDP), the same type of immune attack develops slowly over at least eight weeks and follows a prolonged, relapsing course.
In both conditions, the immune system targets myelin, the coating that allows electrical signals to travel efficiently along nerves. When myelin is stripped away, nerve signals slow down dramatically or fail to reach their destination entirely. The result can range from tingling and numbness to significant muscle weakness and loss of reflexes. Other autoimmune conditions, including lupus and rheumatoid arthritis, can also cause neuropathy through chronic inflammation of nerve tissue or the blood vessels feeding it.
Inherited Genetic Conditions
Charcot-Marie-Tooth disease (CMT) is the most common inherited neuropathy, and it almost always shows up in the feet first. The earliest symptoms are typically muscle wasting in the feet, leading to structural changes: high arches, flat feet, or hammer toes. People with CMT often have difficulty flexing the foot or walking on their heels, and they develop a characteristic high-stepping gait to compensate. Decreased sensitivity to touch, temperature, and pain in the feet and lower legs is common, though some people experience burning or aching sensations instead.
The genetics are well mapped. In the most common form (CMT1), 70% to 80% of cases trace back to an extra copy of a single gene on chromosome 17. Other forms involve mutations in genes responsible for nerve fiber structure or the connections between nerve cells. Because CMT is inherited, it tends to run in families and usually becomes apparent in adolescence or early adulthood, though severity varies widely even within the same family.
Heavy Metal and Environmental Toxins
Exposure to heavy metals like lead, arsenic, and mercury can damage peripheral nerves, though this is a less common cause than diabetes or nutritional deficiency. Each metal tends to affect nerves differently. Lead primarily causes motor nerve damage, leading to muscle weakness, foot drop, and difficulty walking. Arsenic and mercury tend to affect sensory nerves more, causing numbness and tingling. Mercury specifically targets the nerve cell clusters near the spinal cord.
These exposures typically occur through occupational contact, contaminated water, or certain living conditions. One challenge with heavy metal neuropathy is that low-level, chronic exposure can cause subtle nerve damage that is difficult to trace back to a specific source. Blood or urine testing for heavy metals is most useful when done shortly after exposure.
How Nerve Damage Is Confirmed
When the cause of foot neuropathy isn’t obvious from your medical history, two tests are commonly used together. Nerve conduction studies measure how fast and how strongly electrical signals travel along your nerves. A damaged nerve produces a slower, weaker signal than a healthy one. Electromyography (EMG) checks whether your muscles are responding properly to those nerve signals. A healthy muscle at rest produces no electrical activity, so any signal detected while you’re relaxed suggests nerve or muscle damage.
Used together, these tests help distinguish between nerve problems and muscle problems, and they can reveal whether the damage affects the insulating coating around nerves (suggesting an autoimmune or inherited cause) or the nerve fibers themselves (more typical of diabetes, toxins, or nutritional deficiency). Blood work to check glucose levels, B12, thyroid function, and inflammatory markers rounds out the diagnostic picture. In the 20% to 25% of cases where no cause is identified, the neuropathy is classified as idiopathic, though many of these cases are thought to involve early metabolic problems like prediabetes that haven’t yet been detected.