Numbness describes a loss of sensation or feeling in a part of your body. It is often also used to describe other changes in sensation, such as burning or a pins-and-needles feeling. Numbness can occur along a single nerve on one side of the body, or it may occur symmetrically, on both sides of the body. Weakness, which is usually caused by other conditions, is often mistaken for numbness.

Numbness is caused by damage, irritation or compression of nerves. A single nerve branch or several nerves may be affected, as with a slipped disk in the back or carpal tunnel syndrome in the wrist. Certain diseases such as diabetes, or toxins such as chemotherapy drugs or alcohol, can damage the longer, more-sensitive nerve fibers (such as those going to your feet) and cause numbness.

Numbness commonly affects nerves outside of the brain and spinal cord, usually causing a lack of sensation 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 will need detailed information about your symptoms to diagnose the cause of your numbness. A variety of tests may be needed to confirm the cause before appropriate treatment can begin.

Possible causes of numbness in one or both of your hands include:

Brain and nervous system conditions

• Acoustic neuroma
• Brain aneurysm
• Brain AVM (arteriovenous malformation)
• Brain tumor
• Guillain-Barre syndrome
• Herniated disk
• Paraneoplastic syndromes of the nervous system
• Peripheral nerve injuries
• Peripheral neuropathy
• Spinal cord injury
• Spinal cord tumor
• Stroke
• Transient ischemic attack (TIA)
• Transverse myelitis

Trauma or overuse injuries

• Brachial plexus injury
• Carpal tunnel syndrome
• Frostbite

Chronic conditions

• Alcohol use disorder
• Amyloidosis
• Charcot-Marie-Tooth disease
• Diabetes
• Fabry's disease
• Multiple sclerosis
• Porphyria
• Raynaud's disease
• Sjogren's syndrome

Infectious diseases

• Leprosy
• Lyme disease
• Shingles
• Syphilis

Treatment side effects

• Side effects of chemotherapy or anti-HIV drugs

Other causes

• Heavy metal exposure
• Thoracic aortic aneurysm
• Vasculitis
• Vitamin B-12 deficiency

Numbness can have a variety of causes. Most are harmless, but some can be life-threatening.

Call 911 or seek emergency help if your numbness:

• Begins suddenly
• Follows a recent head injury
• Involves an entire arm or leg

Also seek emergency medical care if your numbness is accompanied by:

• Weakness or paralysis
• Confusion
• Difficulty talking
• Dizziness
• Sudden, severe headache

You are likely to have a CT scan or MRI if:

• You've had a head injury
• Your doctor suspects or needs to rule out a brain tumor or stroke

Schedule an office visit if your numbness:

• Begins or worsens gradually
• Affects both sides of the body
• Comes and goes
• Seems related to certain tasks or activities, particularly repetitive motions
• Affects only a part of a limb, such as your toes or fingers