Neuropathy is damage to the nerves outside your brain and spinal cord, and it affects roughly 2.4% of the general population, rising to over 8% in people aged 55 and older. These peripheral nerves carry signals between your brain and the rest of your body, so when they’re damaged, you can lose feeling, muscle control, or the ability to regulate automatic functions like blood pressure and digestion. The causes range widely, from diabetes and nutritional deficiencies to physical injuries and certain medications.
How Peripheral Nerves Work
Your peripheral nervous system is essentially a massive communication network. It relays instructions from your brain to your muscles, sends sensory information like temperature and pain back to your brain, and quietly manages functions you never think about, like heart rate and sweating. Neuropathy disrupts this network, and the symptoms you experience depend entirely on which type of nerve fiber is affected.
There are three categories. Sensory nerves handle touch, temperature, vibration, and pain. Motor nerves control the muscles you move voluntarily, like those used for walking, gripping, or speaking. Autonomic nerves manage unconscious processes: breathing, digestion, blood pressure regulation, and gland function. Damage can hit one type or all three simultaneously.
What Neuropathy Feels Like
The most common early symptoms involve the sensory nerves, and they typically start in the longest nerves first, meaning the feet and hands. Many people describe tingling, numbness, or a “pins and needles” sensation in the toes or fingers that gradually spreads upward. This pattern is sometimes called a “stocking-glove” distribution because the affected areas match where socks and gloves would cover.
As the damage progresses, you might notice burning pain, sharp or stabbing sensations, or extreme sensitivity to touch. Some people lose the ability to detect temperature changes or feel pain from cuts, which creates a real risk of unnoticed injuries. If motor nerves are involved, muscle weakness, cramping, and twitching can develop, along with difficulty walking or holding objects. Autonomic nerve damage shows up differently: excessive sweating, drops in blood pressure when standing, heat intolerance, digestive problems, or bladder dysfunction.
Diabetes Is the Leading Cause
Chronically high blood sugar is the single most common trigger for peripheral neuropathy. The damage happens through several overlapping mechanisms, all driven by too much glucose circulating in the bloodstream over time.
Excess glucose gets converted into a sugar alcohol called sorbitol, which builds up inside nerve cells and disrupts their water balance. This creates osmotic stress that forces out protective compounds the nerve needs to function. At the same time, glucose reacts with proteins in the body to form harmful compounds that bind to nerve tissue and blood vessel walls, triggering inflammation and damaging the tiny capillaries that supply oxygen to nerves. High blood sugar also ramps up production of unstable oxygen molecules (free radicals) that directly injure nerve fibers and the fatty coating that insulates them.
The combined result is that nerves lose their energy supply, their protective insulation degrades, and the small blood vessels feeding them become constricted or blocked. Nerve signals slow down, weaken, and eventually stop reaching their destination. This is why blood sugar management is so central to preventing or slowing diabetic neuropathy.
Nutritional Deficiencies
Vitamin B12 plays a critical role in maintaining the fatty coating (myelin) that wraps around nerve fibers and helps signals travel quickly. When B12 levels are too low, that coating breaks down, leading to abnormal fatty composition in the nerve’s insulation. The result is tingling, numbness, and balance problems that can become permanent if the deficiency goes uncorrected for too long. People most at risk include older adults, strict vegans, and those taking certain acid-suppressing medications that interfere with B12 absorption.
Folate deficiency can contribute as well, particularly in people who drink heavily. Chronic alcohol use creates a double problem: it depletes B vitamins and folate while also directly interfering with enzyme activity in the liver that nerves depend on for healthy metabolism. Long-term heavy drinking is one of the most common non-diabetic causes of neuropathy.
Autoimmune Conditions
In autoimmune neuropathies, the immune system mistakenly attacks peripheral nerve tissue. Guillain-Barré syndrome is one of the most dramatic examples. It causes rapid-onset weakness that typically starts in the legs and moves upward, sometimes affecting breathing muscles within days or weeks. The immune system targets the nerve insulation itself, stripping it away and blocking signal transmission.
Other autoimmune conditions linked to neuropathy include lupus, rheumatoid arthritis, and Sjögren’s syndrome, where chronic inflammation gradually damages nerve fibers over months or years. These cases tend to progress more slowly than Guillain-Barré but can still cause significant numbness, pain, and weakness if the underlying autoimmune process isn’t controlled.
Infections That Damage Nerves
Several infections can target peripheral nerves directly. The varicella-zoster virus, which causes chickenpox, can reactivate decades later as shingles and inflame nerve fibers along a single nerve path, leaving behind lasting pain called postherpetic neuralgia. Lyme disease, transmitted by tick bites, can cause nerve inflammation that leads to facial weakness, numbness, and shooting pain. HIV can damage nerves both directly and through the immune dysfunction it creates.
Medications and Toxic Exposures
Certain cancer treatments are well-known causes of neuropathy. Chemotherapy drugs including taxanes, platinum-based agents, vinca alkaloids, and several others cause different types of direct injury to nerve cells. This chemotherapy-induced neuropathy can begin during treatment and, in some cases, persist long after treatment ends. Symptoms typically start in the fingers and toes and may include numbness, tingling, and difficulty with fine motor tasks like buttoning a shirt.
Beyond chemotherapy, other medications can contribute, including certain antibiotics, anti-seizure drugs, and drugs used to treat HIV. Industrial chemicals, heavy metals like lead and mercury, and long-term solvent exposure also carry neuropathy risk.
Physical Injury and Nerve Compression
Nerves are physically fragile. A car accident, a fall, or a sports injury can stretch, crush, or sever peripheral nerves. Even without a dramatic event, repetitive motion or sustained pressure can compress a nerve enough to cause damage. Carpal tunnel syndrome is the most familiar example: the median nerve gets squeezed as it passes through a narrow channel in the wrist, producing numbness and tingling in the hand.
Similar compression can happen elsewhere. A herniated disc in the spine can press on nerve roots. Sitting in one position for extended periods, using crutches, or even wearing a cast can put enough pressure on a nerve to disrupt its signals. People with diabetes are especially vulnerable to compression injuries because their nerves are already weakened by metabolic damage.
How Neuropathy Is Diagnosed
Diagnosis usually starts with a physical exam testing your reflexes, muscle strength, and ability to feel sensations like vibration, light touch, and temperature. Two specialized tests help confirm the diagnosis and measure how severe the damage is.
A nerve conduction study sends small electrical impulses along a nerve and measures how fast the signal travels. Healthy nerves transmit signals quickly and strongly. A damaged nerve produces a slower, weaker signal. This test identifies which nerves are affected and whether the insulation around the nerve or the nerve fiber itself is the problem.
An electromyography (EMG) test checks how muscles respond to nerve signals. A thin needle electrode inserted into the muscle records its electrical activity at rest and during contraction. A healthy muscle at rest produces no electrical signals. If the muscle shows activity while you’re not moving it, or produces abnormal patterns during movement, that points to nerve damage affecting the muscle’s nerve supply. Together, these two tests map out where the damage is and how extensive it has become, which helps guide treatment toward the underlying cause.
Causes That Are Often Overlooked
While diabetes, alcohol, and vitamin deficiencies get the most attention, neuropathy can also result from kidney disease, liver disease, thyroid disorders, and bone marrow conditions. In roughly 25 to 30 percent of cases, no identifiable cause is found, a condition called idiopathic neuropathy. This is more common in older adults and tends to progress slowly, primarily affecting sensory nerves in the feet. Even without a clear cause, the symptoms can still be managed through pain control and strategies to prevent falls and injuries from loss of sensation.