Numbness In The Left Arm and Hand: Causes And Treatment

Numbness in any part of the body is not a normal sensation, especially if it persists, and may be due to a number of reasons. It is commonly due to a problem affecting a nerve or the collection of nerves supplying an area of the body. Numbness due to nerve affectation is caused by damage, compression or irritation of the nerves. It may also be as a result of trauma, or surgery.

In this article, we will examine the several reasons why a person can have numbness in the body, especially in the left arm and hand with details on how it’s treated.

What Causes Numbness In The Left Arm and Hand?

A gradual, temporary feeling of numbness in your arm is often harmless and will usually resolve on its own. If it occurs frequently or you have other symptoms which accompany the numbness in your hands, you may need to seek emergency care.

There are a dozen reasons why you may feel some numbness in your left arm but here are the commonest ones:

1. Sleep

sleep position

Sleeping in an uncomfortable bed is likely to cause you to sleep haphazardly. You may sleep for long hours but wake up tired. Sleeping position and duration of sleep is very important to our overall health.


One of the signs of a poor sleep posture is numbness in your hands when you wake up. This is due to the compression of the nerve that supplies the region, causing your hands to become heavy and “lifeless”. To circumvent this, ensure you sleep in a bed with decent space and a comfortable mattress. Also, it is best to use a pillow when you sleep and to lay on your side.

If you wake up with numbness in your hands, move your arms around vigorously to ‘wake up’ the hand.

2. Injury To The Arm

injury to hand

Numbness in your left arm may follow an injury to that limb. This is usually as a result of a fracture, specifically affecting the nerves or blood vessels in your left arm. The extent of numbness is usually a function of the severity of the injury, as well as the nerves affected.

If you have suffered any injuries to your arm, you should seek medical care immediately. In cases of fractures, the ends of the bones must be placed contiguous to each other for healing to take place. Thereafter, movement around that area is limited until healing has taken place. If there are any injuries to the nerves or blood vessels or in the case of major fractures, you may require a specialist intervention and a surgery.

3. Poor Blood Supply


Sometimes, blood vessels supplying oxygen-rich blood (called arteries) and those carrying away oxygen deprived blood (called veins) in your arms may be defective. This is often due to diseases such as hypertension, diabetes mellitus or kidney failure.

Sometimes, malformations in these vessels, as well as inflammation, may cause them to function below par. However, numbness is accompanied by pain in that hand, with cold and clamminess or swelling around the area of the defect.

Treatment is instituted after the cause has been found. It may include surgery or drug therapy.

4. Slipped Disc

vertebral column

In our spines are soft pads lying between the bones of the spinal column called vertebral discs. They play an important role in our general health and wellness. When damaged, the vertebral discs can slip and impinge on the nerves in their path, causing numbness or weakness in the affected region. This is called disc herniation (or slipped disc).

When this happens in the neck, you tend to have numbness in your arms and hands. The discs may also be affected by other diseases, due to years of wear and tear, causing you pain and numbness. An example of this is cervical spondylolysis, a type of arthritis affecting the discs in the neck.

5. Burns

burn injury

Following a burn injury, your left arm may be numb due to the direct effect of the burn injury or the response of your body to the injury. In cases of heat or chemical burns that go beyond the skin layer, the nerves in that area may be destroyed directly. Also, the area of the burn may swell, causing compression of the nerves in your arm.


If you have suffered a burn injury, apply a cold compress and petroleum jelly. You should let your healthcare provider review the injury as soon as possible. In the case of a burn injury spanning a large area or causing a breakage of the skin area, please seek emergency care immediately for proper care.

6. Alcoholic Degeneration

alcohol degeneration

Excessive alcohol intake over a prolonged period may cause you to have some numbness in your hands. This is because alcohol may cause your reserves of minerals and vitamins – mainly vitamin B12, to become depleted. These are necessary nutrients for your nerves. Alongside tingling in your left hand, you may experience weakness, fatigue or yellowness of your skin. You may also start having trouble walking or maintaining your balance.

If you have any of the aforementioned symptoms, you should see your doctor as soon as possible. You will be given high potency vitamins to help combat the nerve damage.

7. Carpal Tunnel Syndrome

carpal tunnel syndrome

This is the compression of the median nerve that supplies the thumb, index and middle fingers and half of the ring finger. In its journey, it passes through a narrow passageway through the center of the wrist called the carpal tunnel. In some cases, the muscles and tissues around the median nerve may swell up, compressing the median nerve and causing numbness as it passes through the carpal tunnel.

It is commonly seen in people who do repetitive tasks around the wrist joint, such as typing. It is also common in pregnant women. In mild cases, medications are offered to help reduce symptoms. When severe or refractive to treatment, surgery is done. A similar condition occurs higher up in the depression at the elbow region called cubital tunnel syndrome. The nerve affected here is the ulnar nerve.

8. Heart Attack

chest pain

Numbness of the left arm may be one of the signs of a heart attack. This is because some nerves carrying information in the heart region are in the same area of the spinal cord as the nerves carrying information from the left limb. Thus, pain from the heart may be referred to the left arm, alongside numbness.

If you are hypertensive or diabetic, a regular review with your healthcare team is necessary to forestall serious complications, such as a heart attack. On your part, taking your medications when necessary at the prescribed dose, as well as inculcating lifestyle changes suggested by your healthcare professional is key to preventing serious complications.

9. Other Diseases

low blood sugar

These are diseases affecting nerves on the surface of the hand (called peripheral nerves). These are a part of the electrical conduction system of the body that help us transmit signals and information from the surface parts of the skin to the brain. In some diseases, these nerves are progressively damaged, which means that they are unable to carry out their functions, causing numbness among other things.

For example, in diabetes mellitus, the nerves in a particular area of the body (more commonly the feet) become less effective, causing numbness due to the high level of sugar in the blood. This is called diabetic neuropathy.

If you have diabetes and have problems with sensation on your hands or feet, you should see your doctor. Other diseases that may cause numbness in your left hand include Multiple Sclerosis, Amyloidosis, HIV, Raynaud’s disease and Thyroid disease. Some drugs are also able to cause nerve damage as a side effect, especially anti-cancer drugs.

10. The Brain


In some cases, albeit rare, numbness in your left-hand may be caused by a problem in the brain. This is usually a stroke or a growing tumor. A stroke is caused by the interruption of blood supply to a part of the brain. When this happens, brain cells start to die within minutes. It may resolve within one day (called a Transient Ischemic Attack or a mini-stroke) or may remain after 24 hours, with permanent brain damage.

Cancers may originate from the brain or spread to the brain from another source (e.g. breast cancer spread to the brain). These conditions present not only with numbness but are usually accompanied by other symptoms, such as a loss of function in the left hand or hand weakness.

When To See A Doctor

when to see a doctor

It is imperative to note that a sudden onset of numbness in your left hand or a rapid deterioration of symptoms is cause for alarm. Additionally, if you notice any of the following, please see your doctor immediately.

  • Loss of consciousness
  • Paralysis
  • Back or jaw pain
  • Shoulder pain
  • Confusion
  • A sudden and/or severe headache
  • A high fever
  • A swelling or an infection
  • Difficulty talking

If you notice the numbness gradually over time, notice it begins after a repetitive activity, it is associated with a certain task or it affects other parts of your body, you should see your doctor as early as you can.


Although there are a number of reasons why you may feel some degree of numbness in your left arm and hand, the only sure way to know the cause, as well as the way to resolve it is to seek medical care. If the numbness starts suddenly or progresses rapidly, the odds of the numbness being a pointer to an underlying condition is much higher.

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