Why do I get pins and needles? Usually a squashed nerve, sometimes a warning

The classic pins-and-needles — a hand or foot that has "gone to sleep" and buzzes back to life when you move it — is almost always harmless. Numbness and tingling are abnormal sensations felt most often in the fingers, hands, feet, arms or legs, and one of the commonest causes is simply sitting or standing in the same position for too long, which puts pressure on a nerve until you shift and the feeling returns [s1]. What changes the picture is tingling that is persistent, spreading, or one-sided rather than fleeting — because then it can mark a nerve being compressed or damaged, from carpal tunnel syndrome [s2], diabetes [s3], or a vitamin B12 deficiency [s4].

The everyday, positional kind

Most pins and needles is transient pressure on a nerve — a crossed leg, an arm slept on, a long stretch in one posture — and it resolves within minutes of relieving the pressure [s1]. This is the version with "no obvious cause" beyond a limb falling asleep, and it needs nothing but a change of position [s1]. Nerves can also be pinched more durably, for example by a herniated disk pressing on the nerves of the spine, which is why numbness that tracks down an arm or a leg sometimes traces back to the neck or lower back rather than to the tingling limb itself [s1].

When a nerve is trapped at the wrist

If the tingling is in the thumb, index and middle fingers, often worse at night, the usual cause is carpal tunnel syndrome — compression of the median nerve as it passes through the wrist, and the most common peripheral nerve entrapment syndrome worldwide [s2]. It is recognised widely and can be diagnosed quickly, and both non-surgical and surgical treatments exist; where symptoms are persistent, nerve-conduction testing can gauge how much the nerve is affected [s2].

When it is metabolic

Two internal causes are worth knowing because they are common and treatable. Diabetes is the first: diabetic neuropathies are the most prevalent chronic complication of diabetes, and distal symmetric polyneuropathy — the "glove and stocking" tingling of the feet and hands — is the typical form [s3]. It occurs in at least 20% of people with type 1 diabetes after 20 years of disease, and may already be present in at least 10–15% of people newly diagnosed with type 2 diabetes [s3]. Up to half of diabetic peripheral neuropathy is asymptomatic, which is why foot checks matter; when it does cause symptoms, neuropathic pain — burning, tingling or shooting, electric-shock-like — is present in up to 25% of people with the condition [s3]. Because the nerve damage tracks with blood-sugar exposure, our explainer on what the A1c number measures is a useful companion.

The second is vitamin B12. A long-standing low B12 level can cause nerve damage, and its symptoms include numbness and tingling of the hands and feet, loss of balance, and problems concentrating [s4]. It is easily measured and corrected, and our guide to the B12 evidence covers who is actually at risk.

The pattern that is an emergency

Most tingling is not urgent, but one pattern is. Sudden numbness or tingling with weakness or an inability to move, slurred speech, a change in vision, difficulty walking, confusion or loss of consciousness is a reason to go to hospital or call the local emergency number, because it can signal a stroke or transient ischaemic attack [s1]. Short of that, tingling that has no obvious cause, that persists, or that is spreading is worth a non-urgent assessment, which typically starts with blood tests including thyroid function and vitamin levels [s1]. Tingling on standing that comes with light-headedness is a different story, covered in why do I get dizzy when I stand up.

This article is informational and is not medical advice; it does not diagnose any individual's symptoms or recommend a specific test or treatment.

Sources

• Numbness and tingling — MedlinePlus, U.S. National Library of Medicine
• Carpal tunnel syndrome: clinical features, diagnosis, and management — The Lancet Neurology, 2016-10-11
• Diabetic Neuropathy: A Position Statement by the American Diabetes Association — Diabetes Care, 2016-12-20
• Vitamin B12 deficiency anemia — MedlinePlus, U.S. National Library of Medicine