Left Arm Numb

Numbness and tingling

Numbness and tingling are abnormal sensations that can occur anywhere in your body, but they are often felt in your fingers, hands, feet, arms, or legs.

The central nervous system comprises the brain and spinal cord. The peripheral nervous system includes all peripheral nerves.

Causes

• Sitting or standing in the same position for a long time
• Injuring a nerve (a neck injury may cause you to feel numbness anywhere along your arm or hand, while a low back injury can cause numbness or tingling along your leg or foot)
• Pressure on the nerves of the spine, such as from a herniated disk
• Pressure on peripheral nerves from enlarged blood vessels, tumors, scar tissue, or infection or due to compression of a body part (such as sitting with legs crossed)
• Shingles or herpes zoster infection
• Other infections such as HIV/AIDS, leprosy, syphilis, or tuberculosis
• Lack of blood supply to an area, such as from hardening of the arteries, frostbite, or vessel inflammation
• Abnormal levels of calcium, potassium, or sodium in your body
• Deficiency of B vitamins such as B1, B6, B12, or folic acid
• Use of certain medicines
• Use of certain illicit street drugs
• Nerve damage due to lead, alcohol, or tobacco, or from chemotherapy medicines
• Radiation therapy
• Animal bites
• Insect, tick, mite, and spider bites
• Seafood toxins
• Congenital conditions that affect the nerves
• Autoimmune diseases that attack the nerves

Numbness and tingling can be caused by other medical conditions, including:

• Carpal tunnel syndrome (pressure on the median nerve at the wrist)
• Diabetes
• Migraines
• Multiple sclerosis
• Seizures
• Stroke
• Transient ischemic attack (TIA), sometimes called a “mini-stroke”
• Underactive thyroid
• Raynaud phenomenon (narrowing of the blood vessels, usually in the hands and feet)

Home Care

Your health care provider should find and treat the cause of your numbness or tingling. Treating the condition may make the symptoms go away or stop them from getting worse. For example, if you have carpal tunnel syndrome or low back pain, your provider may recommend certain exercises or other treatments.

If you have diabetes, your provider will discuss ways to control your blood sugar level.

Low levels of vitamins will be treated with vitamin supplements.

Medicines that cause numbness or tingling may need to be switched or changed. Do not change or stop taking any of your medicines or take large doses of any vitamins or supplements until you have talked with your provider.

Because numbness can cause a decrease in feeling, you may be more likely to accidentally injure a numb hand or foot. Take care to protect the area from cuts, bumps, bruises, burns, or other injuries. If you have chronic numbness of the feet (such as from diabetes), seeing a podiatrist regularly can help prevent complications.

When to Contact a Medical Professional

Go to a hospital or call 911 or the local emergency number if:

• You have weakness or are unable to move, along with numbness or tingling
• Numbness or tingling occur just after a head, neck, or back injury
• You cannot control the movement of an arm or a leg, or you have lost bladder or bowel control
• You are confused or have lost consciousness, even briefly
• You have slurred speech, a change in vision, difficulty walking, or weakness

Contact your provider if:

• Numbness or tingling has no obvious cause (like a hand or foot “falling asleep”)
• You have pain in your neck, forearm, or fingers
• You are urinating more often
• Numbness or tingling is in your legs and gets worse when you walk
• You have a rash
• You have dizziness, muscle spasm, or other unusual symptoms

What to Expect at Your Office Visit

Your provider will take a medical history and perform a physical examination, carefully checking your nervous system.

You will be asked about your symptoms. Questions may include when the problem began, its location, or if there’s anything that improves or worsens the symptoms.

Your provider may also ask questions to determine your risk for stroke, thyroid disease, or diabetes, as well as questions about your work habits and medicines.

Blood tests that may be ordered include:

• Complete blood count (CBC)
• Screening for diabetes with glucose tests
• Electrolyte level (measurement of body chemicals and minerals) and liver function tests
• Thyroid function tests
• Measurement of vitamin levels, particularly vitamin B12
• Heavy metal or toxicology screening
• Sedimentation rate
• C-reactive protein

Imaging tests may include:

• Angiogram (a test that uses x-rays and a special dye to see inside the blood vessels)
• CT angiogram of the head and neck
• CT scan of the head
• CT scan of the spine
• MRI of the head
• MRI of the spine
• Ultrasound of neck vessels to determine your risk for TIA or stroke
• Vascular ultrasound
• X-ray of the affected area

Other tests that may be done include:

• Electromyography and nerve conduction studies to measure how your muscles respond to nerve stimulation
• Lumbar puncture (spinal tap) to rule out central nervous system disorders
• Cold stimulation test may be done to check for Raynaud phenomenon
• Genetic testing for nerve problems that run in families.

References

Abbott EE, Bunney EB. Peripheral nerve disorders. In: Walls RM, Hockberger RS, Gausche-Hill M, Erickson TB, Wilcox SR, eds. Rosen’s Emergency Medicine: Concepts and Clinical Practice. 10th ed. Philadelphia, PA: Elsevier; 2023:chap 93.

McGee S. Examination of the sensory system. In: McGee S, ed. Evidence-Based Physical Diagnosis. 5th ed. Philadelphia, PA: Elsevier; 2022:chap 62.

Swartz MH. The nervous system. In: Swartz MH, ed. Textbook of Physical Diagnosis: History and Examination. 8th ed. Philadelphia, PA: Elsevier; 2021:chap 21.

Version Info

Last reviewed on: 4/29/2023

Reviewed by: Joseph V. Campellone, MD, Department of Neurology, Cooper Medical School of Rowan University, Camden, NJ. Review provided by VeriMed Healthcare Network. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

Left Arm Numb

If your left arm is numb, you can’t feel anything, except maybe tingling. You may also have arm weakness. Many things can cause numbness in the arm, from sleeping on it wrong to having a heart attack. Treatment varies widely depending on the cause. Seek immediate medical attention if you have numbness plus any other serious symptoms.

Overview

What is left arm numbness?

If your left arm is numb, you can’t feel anything from your shoulder to your hand. You may also have weakness in your arm, or a sense of “pins and needles” or tingling.

Possible Causes

Why is my left arm numb?

Many things can cause a numb left arm. Some simple explanations might be sleeping on your arm the wrong way or having a migraine headache. Numbness due to those causes will go away in a short time.

However, more serious causes of left arm numbness or tingling that require medical attention include the following:

Heart attack

During a heart attack, a coronary artery becomes blocked. This blockage leads to a lack of blood flow, which can cause left arm numbness. A heart attack often also causes pain or pressure in your chest, neck, arm, face or back. Other symptoms of a heart attack include shortness of breath, dizziness and nausea.

A heart attack is a medical emergency. If you think you’re having a heart attack, take an aspirin and call 911 or go to an emergency room immediately.

Stroke

When a blood vessel in your brain becomes blocked or bursts, your brain might not get enough blood and oxygen. Stroke can cause numbness in several areas of your body, including your left arm. Other signs include trouble with balance, coordination and speech, as well as headache and confusion.

Stroke symptoms tend to happen on one side of your body. A mini-stroke (transient ischemic attack, or TIA) has similar symptoms, but the decreased blood supply to your brain is temporary.

A stroke is a medical emergency. If you think you’re having a stroke, call 911 or go to an emergency room immediately.

Spinal problems

Issues with your spine can result in pinched nerves in your neck, another possible cause of arm numbness. Other signs may include neck pain or stiffness, muscle spasms, dizziness, muscle weakness and headaches. Examples of spinal problems include:

• Cervical spondylosis, a natural wearing down of cartilage, discs, ligaments and bones in your neck.
• Herniated disk, or slipped disk, in your neck.
• Spinal stenosis in your neck, an age-related narrowing of your spinal canal.

Nerve problems

Nerves are part of your nervous system, which sends messages from your brain to the rest of your body. Nerve damage or compressed nerves can lead to numbness and tingling. Other symptoms may include a tingling or burning sensation, weakness in the muscles or strange reactions to touch (oversensitivity or not feeling it). Examples of nerve problems that can cause arm numbness include:

• Carpal tunnel syndrome, caused by increased pressure in the median nerve in your wrist.
• Injury to the brachial plexus, a network of nerves in your shoulder.
• Peripheral neuropathy, which is common in people with diabetes. It can also happen when your body isn’t getting enough vitamin B1 or B12.
• Pinched nerve, when some other tissue presses on a nerve.
• Thoracic outlet syndrome, which is pressure, injury or irritation of the nerves or blood vessels in your lower neck and upper chest.

Trauma

Trauma means injury, and certain injuries can lead to arm numbness. For example, a burn on your skin can damage the nerves responsible for feeling and sensation. A bone fracture in your left arm can also cause numbness. If you have a burn that’s causing numbness or think you may have broken a bone, seek medical attention immediately.

Poor blood circulation

Some people have problems with the arteries and veins that carry blood through their bodies. Vascular disease can cause numbness and tingling in the your arm. Other symptoms include pale or bluish skin, slow or no growth of leg hair or toenails, or sores on your lower body that heal slowly. Another possible sign is thin, brittle, shiny or cold skin on your legs and feet.

Allergic reaction

An allergic reaction can cause numbness in any area of your body. For example, a reaction to a spider bite on your left arm could cause numbness. The area also may be swollen, itchy and red.

Multiple sclerosis

Numbness or tingling in your arm can be an early sign of multiple sclerosis (MS). MS is a disorder that affects the brain and spinal cord. If MS causes nerve damage, it can lead to a lack of feeling in your arm. Other MS symptoms include balance and coordination problems, dizziness or vertigo, and fatigue (extreme tiredness).

Lyme disease

Lyme disease is a bacterial disease often spread by tick bites. It can cause areas of numbness. Other symptoms include rash, headaches, body aches, stiff neck, fever, swollen glands and facial paralysis.

Lead poisoning

Lead poisoning occurs when a person swallows or breathes in enough lead, a poisonous metal. Lead is found in paints, water and other household items, especially older objects. High levels of lead poisoning in adults may cause numbness in your arms or legs. Other signs include a metallic taste, cramps, vomiting, changes in behavior, headaches, fatigue, muscle weakness and weight loss.

Care and Treatment

How are left arm numbness and tingling treated?

Treatments for arm numbness vary widely depending on the cause.

If you don’t have any other symptoms, consider trying a few things at home before you seek medical attention:

• Apply cold or heat.
• Massage the area.
• Rest.
• Stretch or do another light exercise.