Numbness is caused by damage, irritation or compression of nerves. A single nerve branch or several nerves may be affected. Examples include a slipped disk in the back or carpal tunnel syndrome in the wrist. Certain diseases such as diabetes or toxins such as chemotherapy or alcohol can damage the longer, more-sensitive nerve fibers. These include the nerve fibers that go to the feet. The damage can cause numbness.

Numbness commonly affects nerves outside of the brain and spinal cord. When these nerves are affected, it can cause a lack of feeling in the arms, legs, hands and feet.

Numbness alone, or numbness associated with pain or other unpleasant sensations, isn't usually due to life-threatening disorders such as strokes or tumors.

Your doctor needs detailed information about your symptoms to diagnose the cause of your numbness. A variety of tests may be needed to confirm the cause before treatment can begin.

Possible causes of numbness include:

Brain and nervous system conditions

1. Acoustic neuroma
2. Brain aneurysm
3. Brain AVM (arteriovenous malformation)
4. Brain tumor
5. Guillain-Barre syndrome
6. Herniated disk
7. Paraneoplastic syndromes of the nervous system
8. Peripheral nerve injuries
9. Peripheral neuropathy
10. Spinal cord injury
11. Spinal cord tumor
12. Stroke
13. Transient ischemic attack (TIA)
14. Transverse myelitis

Trauma or overuse injuries

1. Brachial plexus injury
2. Carpal tunnel syndrome
3. Frostbite

Chronic conditions

1. Alcohol use disorder
2. Amyloidosis
3. Charcot-Marie-Tooth disease
4. Diabetes
5. Fabry's disease
6. Multiple sclerosis
7. Porphyria
8. Raynaud's disease
9. Sjogren's syndrome (a condition that can cause dry eyes and a dry mouth)

Infectious diseases

1. Leprosy
2. Lyme disease
3. Shingles
4. Syphilis

Treatment side effects

1. Side effects of chemotherapy or anti-HIV drugs

Other causes

1. Heavy metal exposure
2. Thoracic aortic aneurysm
3. Vasculitis
4. Vitamin B-12 deficiency