A foot “falling asleep” after sitting in one position is normal. But repeated or persistent tingling, burning or numbness without an obvious reason may point to a nerve problem.
Seven common causes
- Diabetes: uncontrolled sugar over years causes symptoms starting in both soles and slowly spreading upward.
- Vitamin B12 deficiency: more common in vegetarians, older adults and those on long-term acid-reducing medicines or metformin. Weakness, anaemia and forgetfulness may accompany it.
- Carpal tunnel syndrome: nerve compression at the wrist causes tingling from the thumb to the ring finger, especially at night or when holding a phone. Common in homemakers, tailors and computer users.
- Pinched nerves in the neck or back: tingling with pain spreading from the neck to the arm, or from the back to the leg.
- Thyroid and kidney disease.
- Alcohol and certain medicines: some drugs for tuberculosis, cancer and other conditions can damage nerves.
- Anxiety and panic attacks: rapid breathing causes temporary tingling of the lips and fingers.
Emergency — GBS: tingling in both legs followed within days by rapidly ascending weakness, difficulty walking or climbing stairs — especially after diarrhoea or fever — may be Guillain-Barré syndrome (GBS), which can affect breathing muscles. Go to hospital urgently.
Stroke warning: sudden numbness on one side of the body (face, arm, leg) may be a stroke.
Tests that may be needed
- Blood sugar, HbA1c, vitamin B12, thyroid and kidney tests
- NCS/EMG to assess nerve function
- An MRI of the neck or back when indicated
Treatment
Treatment depends on the cause — B12 replacement for deficiency, a wrist splint (and sometimes minor surgery) for carpal tunnel, and sugar control plus nerve-pain medicine for diabetes. Don't waste time self-medicating with “nerve vitamins”; find the real cause first.