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.
