What Causes Numbness and Tingling?
Numbness (loss of sensation) and tingling ("pins and needles") are symptoms of nerve dysfunction — either from pressure on a nerve, damage to the nerve itself, or disruption of the signals travelling between nerves and the brain. The location, pattern, and character of the sensations provide important diagnostic clues.
Common Causes
Nerve Compression
Carpal tunnel syndrome is the most common single nerve entrapment — compression of the median nerve at the wrist causes tingling and numbness in the thumb, index, middle, and half the ring finger, often worse at night or when driving. Cubital tunnel syndrome (ulnar nerve at the elbow) causes tingling in the little and ring fingers. Cervical radiculopathy (pinched nerve in the neck) can cause numbness radiating down the arm; lumbar radiculopathy causes similar symptoms down the leg.
Vitamin B12 Deficiency
Vitamin B12 is essential for myelin — the protective sheath surrounding nerves. Deficiency causes a "stocking-glove" pattern of numbness: symmetrical, beginning at the fingertips and toes and spreading upward. At-risk groups include vegans and vegetarians (B12 is found only in animal products), people taking metformin or proton pump inhibitors long-term, and older adults with reduced gastric acid production. B12 deficiency neuropathy is reversible if caught early — but can become permanent.
Diabetic Peripheral Neuropathy
The most common complication of diabetes, affecting up to 50% of people with long-standing diabetes. High blood sugar damages small blood vessels that supply nerves, causing length-dependent neuropathy: numbness and burning pain beginning in the feet and slowly creeping upward. Unlike most neuropathies, diabetic neuropathy is often painful as well as numb.
Hypothyroidism
Low thyroid hormone causes accumulation of fluid in carpal tunnels and peripheral nerve sheaths, leading to numbness and tingling — often in conjunction with other hypothyroid symptoms (fatigue, weight gain, cold intolerance). Thyroid replacement therapy typically resolves the neuropathy.
Multiple Sclerosis (MS)
MS causes patches of demyelination in the brain and spinal cord, which can produce numbness or tingling in virtually any distribution — often in one limb, the face, or crossing the midline of the body. MS typically affects young adults (20–40) and presents with neurological symptoms that develop over days and (in the early phase) improve over weeks.
Positional/Transient Causes
Sitting cross-legged, sleeping on an arm, or prolonged pressure on a nerve causes temporary numbness that resolves within minutes. These are not concerning unless they happen without obvious positional cause.
Warning Signs That Need Urgent Evaluation
- Sudden numbness on one side of the body (face, arm, or leg) — could indicate stroke
- Numbness after a head or spinal injury
- Numbness with weakness, bladder/bowel changes, or loss of coordination
- Progressive, worsening numbness without clear cause
Diagnosis and Treatment
Diagnosis involves blood tests (B12, glucose, HbA1c, TSH, inflammatory markers), nerve conduction studies (to locate and characterise nerve damage), and sometimes MRI. Treatment targets the underlying cause: B12 supplementation, glucose control, thyroid replacement, nerve decompression surgery (for carpal tunnel), or disease-modifying therapy for MS. Symptomatic relief for neuropathic pain uses duloxetine, pregabalin, gabapentin, or tricyclic antidepressants.