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You can have left arm numbness due to your sleeping position or an injury. But it can also indicate underlying health conditions, including heart attack or stroke, that may need medical attention.

Left arm numbness could be due to something as simple as how you sleep or as serious as a heart attack. In between are dozens of other potential causes. This applies to numbness in the right arm as well.

Continue reading to learn about some potential causes of a numb left arm.

Problems with your arteries and veins, such as vascular disorders, can affect the blood supply in your arms. Vascular disorders are more likely to occur if you have:

They can also be due to:

  • injury
  • tumors
  • other irregularities

When you experience numbness in your arms and hands, you might also have:

  • tingling
  • pain
  • swelling
  • abnormal coloring of the fingertips
  • cold fingers and hands

Treatment for a numb arm depends on the cause and may include pressure wraps or a surgical procedure to repair the affected blood vessel.

Learn more about the causes and symptoms of poor circulation.

Numbness in your arm could be a symptom of peripheral neuropathy. This means that there’s some damage in the peripheral nervous system. Arm numbness is one symptom of this condition.

Other symptoms of peripheral neuropathy are:

  • tingling or burning sensations
  • muscle weakness
  • abnormal reactions to touch

Some of the more severe symptoms are:

  • muscle wasting or muscle thinning
  • paralysis in the affected area
  • organ dysfunction

Potential causes of this condition include:

  • infection
  • diabetes
  • hormone or vitamin deficiencies
  • toxins

Treatment depends on the cause and can sometimes resolve the problem.

Some natural treatments that may help include:

Find out more about peripheral neuropathy.

Cervical spinal stenosis is a narrowing of the spine in your neck. This can be due to cervical spondylotic myelopathy.

Cervical spinal stenosis can lead to numbness, tingling, and weakness of your arm. It can also affect the feet, urinary bladder, and bowel.

Treatment options include:

  • medications
  • physical therapy
  • surgery, in some cases

A herniated disc in your neck can cause:

  • numbness
  • weakness
  • a tingling sensation in one arm
  • radiating pain in the arm, neck, or shoulders

You can treat it with:

  • rest
  • hot and cold compresses
  • over-the-counter (OTC) pain relievers

If symptoms continue, try to see a doctor. They may recommend prescription medications or surgery.

Hemiplegic migraine causes temporary weakness on one side of the body. It can cause your arm to go numb or develop that “pins and needles” feeling.

Migraine also causes:

  • one-sided head pain
  • nausea
  • light sensitivity

Treatment for migraine includes OTC and prescription medications.

For some people, numbness of the arm can be a symptom of a heart attack.

Other symptoms include:

  • chest pain and pressure
  • pain in the jaw, the back, or either arm
  • shortness of breath
  • dizziness
  • nausea or vomiting

A heart attack is a life threatening emergency. Call 911 or your local emergency services as soon as possible.

Learn more about heart disease, including who is most at risk.

A stroke happens when there’s an interruption in the arteries’ blood supply to part of the brain. Brain cells start to die within a few minutes.

Symptoms of a stroke typically affect one side of the body and can include numbness of an arm, a leg, or the lower face.

Other symptoms are:

  • speech problems
  • confusion
  • sudden headache
  • vomiting
  • dizziness
  • balance and coordination problems

A stroke requires urgent medical treatment.

A transient ischemic attack (TIA) is sometimes called a “ministroke.” The symptoms are the same, but the decreased blood supply to the brain is temporary. You should still see a doctor right away.

Emergency treatment depends on the type of stroke. Treatment will aim to restore blood flow to the brain as soon as possible.

Treatment may also include:

  • clot-busting drugs
  • surgery to repair blood vessels
  • a rehabilitation program

Do you know the warning signs of a stroke?

Bone fractures

Numbness of the arm can result from a bone fracture. You’re also likely to have pain and swelling.

A doctor must reposition the bones, and your arm should not move until it heals. How a doctor does this depends on the extent of the injury.

They may treat a minor fracture with a cast or brace alone. Major breaks can require surgery to align and stabilize the bones correctly.

Here are some first aid tips for broken bones.


A heat or chemical burn on your arm could cause nerve damage that leads to pain, tingling, and numbness. This is especially true of a burn that goes through the skin and destroys nerve endings.

You can treat a minor burn at home with cool water or a cold, wet compress.

If there is broken skin, you can apply petroleum jelly. Don’t use butter or topical steroid ointments because they can lead to infection. Cover the area with a nonstick bandage, and let blisters heal on their own.

Go to the emergency room if you have:

  • a large burn
  • other health issues
  • any symptoms of infection

It’s crucial to call 911 or your local emergency services for severe burns. Such burns can be life threatening and require complex wound care.

Learn more about types of burns and what to do if they happen.

Insect bites

Insect stings and bites don’t affect everyone the same way. Some people have severe allergic reactions, and others experience only minor symptoms. These symptoms may include numbness or tingling around the affected area.

Take care of mild bites by washing the area and applying a cool compress. OTC antihistamines can help reduce itching.

Seek immediate medical attention if you have:

  • trouble breathing
  • swelling of the throat, lips, or eyelids
  • nausea, cramps, or vomiting
  • rapid heartbeat
  • faintness or confusion

What first aid should you give for a bite or sting?

Brachial plexus nerve injury

The brachial nerves run down the arms from the spinal cord in the neck. Injury to these nerves can interrupt messages from the brain to the arms, causing loss of feeling. This can also affect the:

  • shoulder
  • elbow
  • wrist
  • hand

Minor injuries can improve on their own. Severe brachial plexus injuries may require weeks or months of physical therapy. Surgery is sometimes needed.

Other nerve injuries

Overuse peripheral nerve injuries can cause pinched nerves that lead to numbness and pain in your arm or forearm.

Overuse injuries can affect people who:

  • do repetitive actions
  • make abrupt movements
  • have permanent muscle strain

Examples of overuse injuries include:

Ways to remedy these problems include:

  • rest
  • avoiding repetitive tasks
  • avoiding activities that involve pressure to the injured area
  • physical therapy
  • surgery

Cervical spondylosis

Cervical spondylosis with myelopathy — also called cervical spondylotic myelopathy — happens when the spinal cord in your neck becomes compressed or squeezed. This may be due to degenerative arthritis in the neck.

This can cause:

  • numbness, weakness, or pain in your arm and hand
  • neck pain
  • trouble using your hands or walking

A neck brace or physical therapy may be enough to treat this condition. Otherwise, you might need medication or surgery.

Multiple sclerosis

Numbness and tingling are often part of the first symptoms of multiple sclerosis (MS). Numbness in your arm can make it difficult to lift or hold things well. MS interrupts signals between the brain and the rest of the body.

Some other symptoms of MS are:

  • balance and coordination problems
  • fatigue
  • dizziness or vertigo

There’s no specific treatment for numbness or tingling from MS. It may get better when your flare-up goes away. Doctors often prescribe corticosteroids to treat flare-ups. These can also help normalize sensation in your arm.

Can diet help manage the symptoms of MS?

Vascular thoracic outlet syndrome

Sometimes, nerves or blood vessels that affect your arms become compressed. This can lead to numbness, tingling, and pain in your arms, hands, and neck. Your hands might turn pale blue or be slow to heal wounds.

Treatment options for vascular thoracic outlet syndrome include:

  • medications
  • physical therapy
  • surgery, in some cases

Vitamin B12 deficiency

Peripheral neuropathy can happen when you don’t get enough vitamin B12. You might also develop anemia. Other symptoms of nerve damage are:

  • numbness, tingling, or pain in your hands or feet
  • lack of coordination
  • sensory loss
  • general weakness

Treatment involves consuming foods that contain vitamin B12, such as:

  • red meat
  • poultry
  • eggs
  • fish
  • dairy products
  • dietary supplements

Which other foods are high in vitamin B12?

Wernicke-Korsakoff syndrome

Wernicke-Korsakoff syndrome can also cause peripheral neuropathy. The syndrome is due to a deficiency of thiamine (vitamin B1).

Symptoms include:

  • confusion
  • disorientation
  • an unsteady way of walking

This syndrome is treated with:

  • thiamine replacement therapy
  • avoiding alcohol
  • dietary changes

Learn more about vitamin B1 deficiency and how to resolve it.

Lyme disease

Numbness of the arm can be due to untreated Lyme disease. It can also cause shooting pains or tingling. A few other symptoms are:

  • skin irritation at the site of the tick bite, or a bull’s-eye rash
  • headache
  • dizziness
  • facial paralysis
  • tendon, muscle, joint, and bone pain

Doctors may use antibiotics to treat Lyme disease.

Learn more about how to recognize Lyme disease.

Lead poisoning

Exposure to high levels of lead can cause numbness of the limbs.

Some other signs and symptoms of acute lead poisoning are:

  • muscle weakness
  • pain
  • nausea
  • vomiting
  • metallic taste in your mouth
  • decreased appetite
  • weight loss
  • kidney damage

Doctors use chelation therapy to remove lead from your system when lead poisoning is severe.

Most causes of numbness can affect either the right or the left arm. Sometimes it can be a sign of a heart attack. In this case, it may be more likely to occur in the left arm.

Temporary numbness in your left arm is usually no cause for alarm. It will likely resolve on its own. But it’s worth calling a doctor if it persists, it’s severe, or you have any concerns.

Seek emergency medical assistance if you also have:

  • chest pain and pressure
  • back, jaw, or shoulder pain
  • skin discoloration
  • swelling or infection
  • breathing or swallowing problems
  • confusion
  • sudden headache
  • facial paralysis
  • nausea or vomiting
  • sudden balance and coordination problems
  • speech problems

The treatment for numbness in the arm will depend on the cause.

But here are some tips that may help you manage arm numbness at home:

  • If you tend to have numb arms in the morning, try adjusting your sleeping position. A wedge pillow can keep you from sleeping on your arms.
  • When your arm becomes numb during the day, try performing simple movements to improve circulation.
  • Avoid repetitive shoulder, arm, wrist, and finger movements. Try to disrupt the pattern by taking frequent breaks from these movements.

If arm numbness interferes with your work or other daily activities, you should seek medical advice. A doctor may identify an underlying condition and suggest treatment to ease the symptoms.

Arm numbness can resolve itself in a matter of days or weeks. The long-term outlook depends on the cause. Talk with a doctor about your specific case.

Various causes can lead to numbness and possible pain and tingling in the left arm. Most of these are just as likely to affect the right arm.

Numbness in an arm is unlikely to be life threatening in itself, but it can be a sign of a more serious disease.

Anyone with severe or persistent numbness may want to speak with a doctor who can help identify possible causes and recommend a solution.

Left arm numbness may also be a sign of a heart attack. If it happens with changes in the left side of the face, this could indicate a stroke. Anyone with symptoms that suggest either of these issues needs immediate medical attention.