What Causes Neuropathy in Feet and Legs? 8 Root Causes Explained

When a neurologist confirms peripheral neuropathy, the first question is rarely "what do I do about it?"

It is usually: "Why did this happen to me?"

That question feels emotional, but it is actually the most practical one you can ask. People are often surprised to learn they can be doing many things right, exercising, keeping their weight in a healthy range, taking their medication, and still develop nerve damage, because blood sugar was running higher than it should have been for longer than anyone realized.

Understanding why neuropathy develops matters more than most people realize. The cause determines the treatment. And in some cases, not all but some, addressing the root cause can slow or even partially reverse the nerve damage.

More than 100 different conditions can cause peripheral neuropathy, according to the Foundation for Peripheral Neuropathy, which lists diabetes, idiopathic neuropathy, and chemotherapy-induced neuropathy as the most common. But the vast majority of cases come from a short list of identifiable causes. This article walks through the 8 most common.

Cause 1: Diabetes, The Number One Trigger

Diabetic neuropathy is the most common form of peripheral neuropathy in the United States. The NIDDK reports that about one-third to one-half of people with diabetes have peripheral neuropathy. Duration is a large part of the risk: a Cochrane review of glucose control and neuropathy notes that neuropathy is present in roughly 10% of people at the time of diabetes diagnosis and in 40% to 50% after ten years.

The mechanism is well understood. Chronically elevated blood sugar damages the small blood vessels that supply nutrients to peripheral nerves. It also directly damages nerve fibers through a process called glycation, where excess glucose attaches to proteins in the nerve fiber and disrupts their function.

The feet and legs are almost always affected first, because the longest nerves in the body (running from the spine to the toes) are the most vulnerable to cumulative damage.

Nerve damage is not limited to people who have crossed the diabetes threshold. A study in Diabetes Care followed people with impaired glucose tolerance and neuropathy through a year of diet and exercise counseling, measuring nerve fibers in skin biopsies, and documented both the baseline fiber loss and its partial recovery. You do not need a formal diabetes diagnosis to have glucose-driven nerve damage.

What this means for you: If you have diabetes or prediabetes and experience tingling, numbness, or burning in your feet, do not wait for your next annual checkup. Ask for a neuropathy screening now. And talk to your doctor about tighter blood sugar control, because it is the most powerful lever you have.

Cause 2: Vitamin B12 Deficiency, The Silent Trigger Most Doctors Miss

Vitamin B12 is essential for maintaining the myelin sheath, the protective coating around nerve fibers. Without adequate B12, nerves begin to demyelinate, and signals are disrupted. The symptoms are nearly identical to diabetic neuropathy: tingling, numbness, and weakness in the feet and hands.

B12 deficiency turns up regularly when neuropathy is worked up properly: it accounted for 9% of cases in a 2019 series of 100 patients with chronic neuropathy. The problem is that it is easy to miss, because standard blood tests often report levels as "normal" using ranges many neurologists consider too low.

Two groups are at particularly high risk:

• People taking metformin, the most commonly prescribed diabetes drug, which reduces B12 absorption in the gut. A 2022 meta-analysis of 17 studies found B12 deficiency in 23.2% of patients taking metformin versus 17.4% of those who were not, with risk rising with dose and duration of use.
• Adults over 50, because stomach acid production declines with age, reducing the ability to absorb B12 from food.

The form of B12 is often debated: methylcobalamin is the active form, while cyanocobalamin has to be converted by the body. Head-to-head evidence in neuropathy is limited, so the more important step is testing rather than choosing a label.

What this means for you: If you take metformin or are over 50, ask your doctor to test both your serum B12 and your methylmalonic acid levels (a more sensitive marker of functional B12 deficiency). B12 deficiency is inexpensive to treat and reversible if caught early.

Cause 3: Alcohol-Induced Neuropathy

Excessive alcohol use is one of the most common, and most preventable, causes of peripheral neuropathy. It causes nerve damage through two mechanisms:

1. Direct toxicity: Alcohol is directly toxic to nerve fibers. Ethanol and its metabolites damage the axons and myelin sheath.
2. Nutritional deficiency: Heavy drinkers often have poor nutrition and are frequently deficient in B1 (thiamine), B6, B12, and folate, all essential for nerve health.

A 2019 systematic review in the Journal of Neurology put the prevalence of peripheral neuropathy among chronic alcohol abusers at 46.3% on nerve conduction testing, and identified the total lifetime dose of ethanol as the most important risk factor.

The characteristic pattern is length-dependent, starting in the feet and working upward, and is often painful, with burning and hypersensitivity that are sometimes more severe than diabetic neuropathy.

What this means for you: If you drink heavily and have foot symptoms, the path forward is clear: reducing alcohol is the single most effective intervention. The same review found that the limited management data available supports B-vitamin regimens that include thiamine. Some recovery of nerve function is possible with abstinence.

Cause 4: Chemotherapy, Chemo-Induced Peripheral Neuropathy (CIPN)

Many chemotherapy drugs damage peripheral nerves as a side effect. This is called chemotherapy-induced peripheral neuropathy (CIPN), and a systematic review and meta-analysis of 31 studies published in Pain found a prevalence of 68.1% when measured in the first month after chemotherapy, falling to 60.0% at three months and 30.0% at six months or more.

The most commonly implicated drugs include oxaliplatin, paclitaxel, cisplatin, bortezomib, and vincristine. Different drugs cause different patterns of nerve damage. Some primarily affect sensory nerves (causing numbness and tingling), while others affect motor nerves (causing weakness) or autonomic nerves.

CIPN can be temporary or permanent. In some cases, it resolves after chemotherapy ends. In others, it persists for years: even at six months or more, roughly 30% of patients still have it.

What this means for you: If you are undergoing chemotherapy and developing tingling or numbness, tell your oncologist immediately. They may be able to adjust your dose or switch medications. Do not assume it is inevitable.

Cause 5: Autoimmune and Inflammatory Conditions

The immune system can attack peripheral nerves directly. Several conditions cause this:

• Guillain-Barre syndrome: The immune system attacks the myelin sheath, causing rapid-onset weakness and numbness. It is rare, and it requires immediate medical attention.
• Chronic inflammatory demyelinating polyneuropathy (CIDP): A slower version of Guillain-Barre, with relapsing-remitting symptoms.
• Lupus, rheumatoid arthritis, and Sjogren's syndrome: All can cause neuropathy through vasculitis (inflammation of blood vessels supplying nerves) or direct immune attack.

Immune-mediated neuropathies show up often enough to matter. In the 2019 series of 100 chronic neuropathy patients, dysimmune causes were the largest single group, including CIDP (8%), paraproteinemic (8%), and celiac-related (6%) neuropathy. The authors recommended routine blood screening for dysimmune neuropathy and celiac disease in anyone whose neuropathy looks idiopathic after first-line testing. These causes matter because they are treatable, often with corticosteroids, IVIG therapy, or immunosuppressants.

What this means for you: If you have an autoimmune condition and develop neuropathy symptoms, this connection should be explored with a rheumatologist and neurologist working together.

Cause 6: Hypothyroidism, The Overlooked Culprit

An underactive thyroid is a frequently missed cause of peripheral neuropathy. Hypothyroidism causes fluid retention throughout the body, including in the tissues surrounding peripheral nerves. This swelling compresses nerve fibers and disrupts their function.

Thyroid disease is common and frequently undiagnosed. Hypothyroid neuropathy typically causes a predominantly sensory neuropathy with numbness and tingling in the hands and feet.

A key feature: hypothyroid neuropathy often improves dramatically with thyroid hormone replacement therapy. This makes it one of the most treatable causes of neuropathy, if it is identified.

What this means for you: TSH (thyroid-stimulating hormone) testing should be part of the standard workup for anyone with new-onset peripheral neuropathy. If your TSH is elevated, treatment may resolve your neuropathy symptoms significantly.

Cause 7: Physical Trauma, Compression, and Repetitive Injury

Some cases of neuropathy are not systemic. They are local. Physical compression or repetitive motion can damage specific peripheral nerves in predictable ways:

• Carpal tunnel syndrome: Compression of the median nerve in the wrist, causing tingling and numbness in the hand and fingers.
• Tarsal tunnel syndrome: Compression of the tibial nerve behind the ankle, causing foot tingling and burning.
• Peroneal nerve palsy: Often caused by prolonged leg crossing, causing foot drop.
• Herniated disc: Can compress nerve roots in the spine, causing radiating pain and numbness in the legs (sciatica).

Nerve compression injuries are generally treatable when identified early, often with physical therapy, ergonomic changes, splinting, or in some cases surgical decompression.

What this means for you: If your neuropathy symptoms are confined to one hand or foot, or follow a specific distribution pattern, a compression injury may be the cause, and it may be fixable.

Cause 8: Toxins, Medications, and Heavy Metal Exposure

A surprising number of common substances can damage peripheral nerves:

Medications:

• Metronidazole (antibiotic)
• Isoniazid (tuberculosis drug)
• Certain HIV antiretrovirals
• Amiodarone (heart rhythm drug)
• Fluoroquinolone antibiotics (in some cases)

Heavy metals:

• Lead, mercury, and arsenic can all cause peripheral neuropathy. Occupational exposure in manufacturing, construction, or certain industrial settings is the most common route.

Industrial chemicals:

• Acrylamide, hexacarbons, and organophosphates (found in some pesticides) are known neurotoxins.

Toxic neuropathy requires identifying and eliminating the source. Chelation therapy is used in heavy metal cases. With medication-induced neuropathy, switching drugs often leads to gradual recovery.

What this means for you: If your neuropathy began shortly after starting a new medication, bring that timeline to your doctor. Drug-induced neuropathy is underdiagnosed because the connection is rarely made.

What About Idiopathic Neuropathy?

Despite thorough testing, a substantial share of peripheral neuropathy cases remain without a clear identifiable cause. This is called idiopathic neuropathy. In the 2019 series of 100 chronic neuropathy patients, 19% stayed idiopathic after full workup.

Idiopathic neuropathy tends to progress slowly and is often less severe than neuropathies with an identified cause. Management focuses on symptom control and preventing further damage through healthy lifestyle choices, particularly blood sugar control (even in people without diabetes), regular exercise, and avoiding alcohol and smoking.

Some so-called idiopathic cases turn out to be pre-diabetic neuropathy (glucose intolerance not yet in the diabetic range) or undetected immune-mediated neuropathy, which makes a thorough evaluation important even when initial tests come back normal.

Getting to the Root Cause: What Tests to Ask For

If you are experiencing neuropathy symptoms, ask your doctor for this baseline blood panel:

• Fasting glucose and HbA1c, which screens for diabetes and prediabetes
• Serum B12 and methylmalonic acid, which detects functional B12 deficiency
• Complete metabolic panel, for kidney and liver function
• TSH, for thyroid function
• CBC, complete blood count
• Serum protein electrophoresis (SPEP), which screens for plasma cell disorders
• Heavy metals panel, if occupational exposure is possible

A neurologist can also order a nerve conduction study (NCS) and EMG, which identify the type and location of nerve damage. This helps narrow the potential causes significantly.

Want to understand more about peripheral neuropathy, what it is, what types exist, and how it is diagnosed? Read the Complete Guide to Peripheral Neuropathy.

Frequently Asked Questions

Can neuropathy be caused by stress?

Stress does not directly damage peripheral nerves, but chronic stress elevates cortisol, which can worsen inflammation and impair blood sugar regulation. Those are two factors that accelerate nerve damage in people already at risk. Additionally, stress-related conditions like anxiety can cause tingling and numbness (from hyperventilation), which can be confused with neuropathy.

Can neuropathy develop suddenly?

Most neuropathy develops gradually over months or years. However, some causes, such as Guillain-Barre syndrome, severe B12 deficiency, acute trauma, or certain toxic exposures, can cause neuropathy that appears or worsens quickly over days or weeks. Rapid onset neuropathy is a medical emergency and should be evaluated immediately.

Is neuropathy hereditary?

Yes, some forms are. Charcot-Marie-Tooth (CMT) disease is the most common hereditary neuropathy. It causes progressive muscle weakness and sensory loss in the feet and legs, typically beginning in childhood or early adulthood. Genetic testing can identify CMT and related hereditary neuropathies.

Can alcohol-related neuropathy be reversed?

Partially. If alcohol use is stopped early enough and nutritional deficiencies (especially thiamine) are corrected, some nerve function can recover. The earlier the intervention, the better the recovery. Permanent damage is more likely with long-duration heavy drinking.

Does poor circulation cause neuropathy?

Poor circulation and neuropathy often coexist, especially in people with diabetes and peripheral artery disease (PAD), but they are distinct conditions. Poor circulation (reduced blood flow to the feet) can contribute to nerve damage over time by depriving nerves of oxygen and nutrients. However, PAD causes different symptoms (pain with walking, cold feet) and requires different treatment. They are frequently confused.

The Bottom Line

Peripheral neuropathy is not one disease. It is a symptom of many. Diabetes, B12 deficiency, alcohol, autoimmune conditions, thyroid disease, physical compression, and toxin exposure are the most common causes. In a meaningful share of cases, no cause is found at all.

What matters most: getting tested early, identifying the root cause if possible, and treating it aggressively. The nervous system has limited capacity to repair itself. Every month you wait is another month of preventable damage.

If you recognize symptoms of neuropathy, start with a conversation with your primary care doctor. Ask for the full blood panel. Ask for a neurology referral. Do not dismiss what your body is trying to tell you.

And if you want to understand what happens to your nerves at a biological level, and what types of neuropathy exist, read the Complete Guide to Peripheral Neuropathy.

NeuropathyHealthGuide Editorial Team

Medical Disclaimer: The NeuropathyHealthGuide Editorial Team is not composed of medical professionals. The information in this article is for educational purposes only and does not constitute medical advice. Always consult a qualified physician or neurologist before making any changes to your health regimen.