6 most common cause(s)
What is numbness in one upper arm?
Numbness is when you feel a loss of sensation, and it can also feel tingly, burning, or like “pins and needles.”
If your upper arm feels numb, that usually means that the nerves that supply the area have been compressed or irritated. Sometimes it means that blood isn’t flowing well to the area. More serious problems can also cause numbness in one upper arm.
Numbness can be caused by trauma from an injury, compressed nerves, or overuse of the upper arm muscles. Other causes of upper arm numbness and tingling include a pinched nerve within the neck or even a mini stroke.
Because numbness in the upper arm by itself is rare, it is important to note other symptoms that you may feel in the upper arm (such as weakness or loss of mobility), or elsewhere on your body, such as slurred speech.
Pro Tip
A common misconception is that numbness is only due to an issue with nerves. —Dr. Mike Gaspar
Causes
1. Asleep arm
Symptoms
- Numbness with pins and needles from the shoulder down to the hand
- May also have sharp or burning pain
You may cause numbness when you fall asleep on your arm or in an unusual position for a long period of time. The position causes stretching or compression in the nerves of the neck, shoulder, or arm.
Treating an asleep arm
To stop the numbness, simply reposition your arm and allow the compressed or stretched nerves to return to their normal, relaxed state.
2. Pinched nerve root in the neck
Symptoms
- Neck pain (often on one side of the neck)
- Sharp pain in one shoulder
- Pain that radiates down the arm from the neck and shoulder
- Numbness and tingling
- Weakness from the shoulder down to the hand
A pinched nerve root in the neck, called cervical radiculopathy, is when a nerve root (the large part of the nerve that comes out of the spinal cord) is compressed by bones, muscles, or other tissues.
It’s often caused by a sudden injury, such as during sports or a car accident, that may lead to disc herniation (bulging of the squishy discs between neck bones). It can also happen from normal wear-and-tear of aging, such as arthritis in the neck bones.
Treating a pinched nerve
A pinched nerve root in the neck may get better with rest or by changing your activity for a few days or weeks. Physical therapy, nonsteroidal anti-inflammatory drugs such as ibuprofen (Motrin) or naproxen (Aleve), and steroid injections into the spinal canal can also be very helpful.
If these measures don’t give you enough relief, you may need surgery to relieve pressure on the nerve root by removing the piece of herniated disc or cleaning out the bone or cartilage damaged by arthritis.
Pro Tip
If a herniated disc is causing the numbness, physical therapy can help improve symptoms. —Dr. Gaspar
3. Brachial plexopathy
Symptoms
- Pain in one arm
- Shoulder pain that shoots to the arm
- Muscle weakness
- Numbness in one arm
The brachial plexus is a cluster of large nerves between the neck and each shoulder. It connects the spinal cord nerves to the nerves in your arms.
Injury to the brachial plexus (brachial plexopathy) can come from sudden forceful movements that cause the shoulder to stretch down while the neck stretches up and away. This often occurs during contact sports like football (a shoulder stinger) or from trauma, such as a car or motorcycle accident.
Treatment
Rest and physical therapy are usually effective in treating brachial plexopathy. If your nerves are permanently damaged, you may need surgery to repair them or to remove irritating scar tissue.
4. Stroke or transient ischemic attack (TIA)
Symptoms
- Dizziness
- Leg numbness
- Arm numbness
- Headache
- Weakness, numbness, and paralysis on one side of the face and body
- Slurred speech
- Abnormal vision
A stroke means that a clot has blocked blood flow somewhere in the brain. When that happens, that part of the brain loses oxygen, and can become permanently damaged. If it's an area of the brain that controls your movement, your arm may feel paralyzed or numb.
A transient ischemic attack (TIA) is sometimes called a "mini stroke" or a "warning stroke." With TIA, the symptoms come and go within minutes because the clot dissolves on its own.
A TIA does not cause permanent damage because it happens so quickly. But it is a warning that a more damaging stroke may happen, so you should see a doctor right away.
Treating stroke/tia
The longer you wait, the greater your chance of having permanent injury or disability. If you suspect that you have had a TIA or a stroke, go to the emergency room or call 911 immediately.
The doctor may give you thrombolytic medication to dissolve the clots and anticoagulant medication to prevent new clots from forming. You may need surgery to clear your arteries.
5. Thoracic outlet syndrome
Symptoms
- Upper back pain
- Neck pain
- Arm weakness
- Back pain that gets worse when sitting
- Upper spine pain
Thoracic outlet syndrome happens when blood vessels or nerves that travel between the collarbone and the first rib are compressed. You may feel a variety of symptoms, depending on the severity and the specific areas that are compressed.
When mostly nerves are affected, you may have numbness and tingling or weakness in your arms. When blood vessels are affected, you may also have discoloration in your hands, cold hands and arms, or pain and swelling.
An anatomical abnormality like having an extra rib below your collarbone can cause thoracic outlet syndrome. Trauma, repetitive motions, or poor posture (slumped over body position) may also cause it.
Treatment
To relieve your symptoms, your doctor will need to address the underlying causes. You may need surgery to remove an extra rib bone.
6. Multiple sclerosis (MS)
Symptoms of multiple sclerosis
- Severe fatigue
- Vision problems
- Numbness or weakness in arms, legs, or body
- Hypersensitivity, particularly in the arms and legs
- Mobility problems
- Loss of coordination
- Difficulty with speech or swallowing
- Constipation
- Bladder control problems
Multiple sclerosis (MS) occurs when the body's immune system attacks nerve fibers and their covering, called myelin, causing permanent scarring called "sclerosis." This damage interferes with the transmission of nerve signals between the brain and different parts of the body.
Doctors don’t know what causes MS, but it usually appears between ages 20 and 50, and is more common in women.
Because MS can affect nerves all over the body, the symptoms—and how severe they are—can vary and are unpredictable. Numbness or hypersensitivity of the arms and legs can be one of the earliest symptoms of MS.
Treating MS
There is no cure for MS. But corticosteroids and plasma exchange (plasmapheresis) can slow the course of the disease and help manage symptoms, improving your quality of life. Some drugs, such as disease-modifying drugs, can also be used to slow the progression of MS. They work by changing the way your immune system works.
7. Vitamin B12 deficiency
Symptoms
- Weakness and fatigue
- Numbness in the arms and legs
- Difficulty walking
- Shortness of breath
- Thinking slowly and forgetfulness
- Vision issues
- Hypoxia (lack of oxygen) or a pale, bluish appearance
- Changes in mood, depression, and irritability
- Insomnia
Vitamin B12 is necessary for producing myelin, which covers and protects your nerves and controls the communication between the nerves and the brain. B12 also controls the production of red blood cells, which carry oxygen throughout the body.
The only food sources of vitamin B12 are animal products, so vegetarians and vegans are prone to a deficiency. If you have a vitamin B12 deficiency, your nerves are less able to send signals to and from the brain, which can lead to numbness.
Treating vitamin B12 deficiency
Eating more vitamin B12-rich foods or taking a multivitamin that contains B12 can help restore levels in your body. If you are severely deficient, you may need weekly B12 injections.
Other possible causes
A number of conditions may also cause numbness in one upper arm. They include deficiencies of certain vitamins and minerals such as magnesium, and tumors that can compress nerves.
When to call the doctor
If you keep feeling upper arm numbness and your arm position isn’t causing it, you should see your primary care doctor.
Should I go to the ER?
You should go to the emergency department if you have any of these signs of a stroke:
- Speech difficulty
- Facial drooping
- Weakness to the point that you can’t raise your arm
- Sudden vision changes
Dr. Rx
Expect your doctor to ask about any other symptoms you are having. They will also ask: Is the numbness affecting one or both arms? Is it all the time, or some of the time? Is there weakness? Pain? —Dr. Gaspar
Treatment and preventative care
At-home care
- Change your sleeping position if you sleep with your arms above your head. That can compress the nerves and make your arm "fall asleep."
- Avoid repetitive motions or cramped positions that put pressure on your shoulders.
- Stand and sit straight with your shoulders back and take breaks from sitting throughout the day to reduce compression and irritation of your nerves.
- Exercise regularly and eat a balanced diet to maintain a healthy weight and control diseases like obesity and diabetes.
- Anti-inflammatory medications (NSAIDs) such as ibuprofen and naproxen can relieve pain from a pinched nerve.
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