Causes of a Numb Thumb or Hand

Pressure on a nerve is one of the most common causes of a numb thumb. Numbness in the thumb can also happen if the nerve supply to the thumb and hand is injured or affected by a medical condition.

Less common but potentially serious causes of a numb thumb include a stroke, a heart attack, or aortic dissection. However, you'll usually have other symptoms (not just a numb thumb) if you have one of these conditions.

This article will go over the most common causes of thumb numbness, as well as less common but more serious causes. You'll also learn when to see a provider for numbness in your thumb and how the conditions that cause thumb numbness are diagnosed and treated.

causes of a numb thumb or hand
Illustration by Emily Roberts, Verywell

Symptoms of Thumb Numbness

Numbness is an unusual sensation that can be hard to describe. Sometimes, people use the word "numb" to mean they have a "pins and needles" feeling (paresthesia) but it can also be used when a person has no feeling at all.

Two questions that you can ask that will help determine what’s causing the thumb numbness are: 

  • Are all areas of your thumb numb? 
  • If not, is it just the front/side/or back of your thumb that is numb?

When to See a Healthcare Provider

If a numb thumb comes on suddenly, is accompanied by other feelings like weakness, has no obvious cause (such as falling asleep on your arm), or is associated with neck or chest discomfort, these can be warning signs of a more serious problem. Don’t wait to get medical attention. 

Numb Thumb: Peripheral Nerve Causes

The hand gets supplied by nerve cords that branch out between the bones in the neck. These branches twist and interlock in a complicated way, then become more well-defined nerves called the median, radial, and ulnar nerves.

While all three nerves are involved in moving the thumb, only the radial and median nerves give sensation to the thumb.

Median Nerve

The median nerve gives sensation to the part of your thumb with the thumbprint hidden when you make a fist (palmar). The nerve also supplies the palmar face of the index and middle fingers.

The median nerve often gets pinched, which gets in the way of its ability to carry electrical signals from the skin to the spinal cord and brain. When the nerve is pinched, it often leads to numbness. Sometimes, weakness can be felt too—particularly in the muscles that bend the thumb toward the base of the little finger.

The most common place for the median nerve to get pinched is in a narrow passage in the wrist where the median nerve travels along several tendons to the fingers (carpal tunnel).

If the tendons there get inflamed, the swelling in the narrow tunnel can lead to a pinched nerve. It can be painful, but it is not always.

The median nerve can also be pinched somewhere in the arm, but this usually causes numbness or weakness in the arm or wrist as well as the hand and thumb.

Radial Nerve

The superficial branch of the radial nerve is responsible for getting sensation from the back of the hand, thumb, and first two fingers back to the brain. If the radial nerve is interrupted, it can cause numbness in the back of the hand.

Damage to the radial nerve is less common than damage to the medial nerve. The trauma is also usually easy to identify—for example, rather than mild swelling pinching the nerve, it could be a bone fracture in the hand that’s causing it.

Unless the damage is just to the superficial branch, some muscle weakness and numbness will also be felt. In the thumb, this effect is most noticeable in the muscle that pulls the thumb away from the first finger (as if you were mimicking the cocked hammer of a gun).

Ulnar Nerve

The ulnar nerve travels from your neck down to your fingers. Injury to the nerve can cause numbness and tingling along the side of your hand, especially your ring finger and little finger. One example is when you whack your elbow (“funny bone”) and feel an uncomfortable tingling shoot down to your fingers.

The ulnar nerve can get pinched, especially as it passes below the elbow. This is called cubital tunnel syndrome, and it can cause numbness and tingling in the ring and little finger, as well as muscle weakness in the hand.

Numb Thumb: Spinal Cord and Brachial Plexus Causes

All these nerves run from the hand to the arm, and then to the spinal cord. Like roads approaching a major city, more and more “traffic" (electrical information) gets intertwined the closer you get to the “center of the action” (the brain).

Nerves that were once separate begin to run side by side, ultimately coming together in the brainstem (an area that’s no bigger around than your thumb). Through that space flows all the important information between your body and your brain.

For this reason, the closer a problem is to the brain, the more likely it is that multiple information flows will get disrupted, like cars piling up on a freeway.

Before hopping on the “freeway” of the spinal cord, electrical information travels through a complicated “on-ramp” called the brachial plexus.

While it's possible that a tiny lesion in this spot could produce numbness in just one thumb, it's unlikely. It becomes even less likely when information enters the spinal cord. Not only would other body parts be numb at this point, but weakness would also develop.

It's worth mentioning that there are a few exceptions to the rule. Sensory and motor information are separated in the spinal cord, beginning from where the nerve roots enter. Motor information enters in the front and sensory information in the back of the spinal cord.

For this reason, it's possible to have only numbness result from a cord lesion. Still, that numbness would most likely affect a large area of the body than just your thumb.

Less Common But Serious Causes of a Numb Thumb

When it comes along with other symptoms, a numb thumb could be a symptom of more serious health conditions. However, it’s important to note that with these causes, a numb thumb would not likely be the only symptom you have. 

Heart Attack

Sometimes, people having a heart attack experience chest pain that is felt down one or both arms. In some people, the discomfort can be a numb, tingling sensation that could be felt in the hand (and therefore the thumb).

People having a heart attack often have other symptoms, like dizziness and feeling short of breath.

Stroke

One of the key signs of a stroke is sudden numbness or weakness, usually on just one side of the body. That could include the hand and thumb.

Other signs of a stroke include trouble speaking or understanding speech, vision problems, and confusion.

Aortic Dissection

When the main artery in the body (the aorta) tears, it’s a life-threatening condition called aortic dissection. 

Pain in the chest is the most common symptom. At first, a person may think they are having a heart attack. The pain from aortic dissection can also be felt in the arm like it can with a heart attack—though this is usually a sign that the tear is getting worse.

An aortic dissection can also cause dizziness, paleness, and feelings of anxiety.

Diagnostic Tests for a Numb Thumb

The tests your provider will want to do will help them figure out what is causing your thumb to be numb and help them pick a treatment.

You probably will not have all of these tests; rather, these are the test your provider may choose from depending on your situation. 

Nerve Tests

Electromyography (EMG) or nerve conduction study (NCS) are tests that check the function of the nerves in your arms and legs. EMG uses needles to check the nerves in the affected muscles. NCS uses electrodes on the skin that deliver a small shock effect to test nerve function.

Both tests can be a little uncomfortable for a few seconds, but most people tolerate them just fine. There should not be any pain or discomfort after the tests are done.

Imaging Tests

You might need to have a brain CT scan or MRI if there is a possibility that the numbness or tingling could be caused by a stroke, multiple sclerosis (MS), head trauma, a tumor, or another medical condition affecting the brain.

There are also special imaging tests that providers can do in an emergency if they’re worried you could have an aortic dissection.

Spinal Tap

A spinal tap (lumbar puncture) might be needed in rare cases, such as if your provider is concerned about a serious illness called Guillain-Barre syndrome (GBS) that often can cause mild numbness or tingling of the feet or hands.

The test can also help your provider check for MS or an infection in your spinal fluid.

Blood Tests

In an emergency situation, a provider can do some blood tests to see if you could be having a heart attack.

There are also some non-emergency blood tests your provider might do. 

Toxins, nutritional deficiencies, and infections can damage the peripheral nerves and cause numbness (peripheral neuropathy)—for example, lead toxicity and vitamin B12 deficiency. Chronic health conditions like diabetes and thyroid disease also can cause peripheral neuropathy.

Your provider may want to do blood tests to check for these causes. However, these conditions tend to affect the whole body at once. It would be unusual for one side of the body to be more affected than the other.

How a Numb Thumb Is Treated

The treatment for a numb thumb depends on what’s causing it. In general, the possible treatments can be divided into a few categories and each one may apply to more than one condition that could cause thumb numbness.

Non-Medication Treatments

If you’ve got an injury that’s causing a numb thumb, you may just need to rest and give your body time to heal. You also may need to avoid certain activities (like sports) or movements (like typing on your computer) that make it worse.

Your provider might recommend that you work with a physical therapist (PT) during your recovery. They can give you exercises that can help with the current injury as well as help you avoid getting another one.

If you’ve had chronic problems with thumb numbness, you may find that certain aspects of your lifestyle tend to make it worse.

For example, your setup at your desk at work might be putting too much pressure on the nerves in your arm and hand. If this is the case, it could be helpful to have an ergonomic assessment to find better ways to support your body while you’re at your desk.

Medications

Your provider might start by having you try over-the-counter (OTC) medications like ibuprofen that help with inflammation. While OTC painkillers won't work for numbness, if the feeling is being caused or made worse by swelling, treating the inflammation might help.

If OTC medicines don’t help or are not strong enough, your provider might have you try a prescription medication that can help bring down inflammation and swelling (corticosteroids).

In some cases, these medications can be injected into your hand rather than taken by mouth as a pill.

There are also some other types of prescription medications that may help with neuropathy, like pregabalin (sold under the brand name Lyrica) and nortriptyline (an antidepressant).

Surgery

Some injuries and conditions may need surgery to fix. A common problem that can cause numbness in your hand and thumb is carpal tunnel syndrome. In some cases, surgery can be done to release the pressure on the nerve.

Other Condition-Specific Treatments

If your provider ends up diagnosing you with a chronic condition that’s affecting more of your body than your thumb, they’ll talk to you about your options for treatment. 

For example, chronic conditions like MS can often be managed with medications. There are also treatments that can be given for the symptoms of GBS that will also help with your recovery.

Emergency situations like strokes and heart attacks usually involve being admitted to the hospital to get medications and have procedures that can help keep more damage from being done to your body as well as try to prevent these conditions from happening again.

Summary

A numb thumb is most often caused by a problem with the nerves that go to the hand. It’s less likely, but other causes like strokes, diabetes, and nutritional deficiencies could cause numbness in the thumb—though, a person will usually have other symptoms too if they have these conditions. 

Your provider can do tests to see how your nerves are working as well as check for and rule out different causes for your thumb numbness, then recommend a way to treat it.

Frequently Asked Questions

How do you relieve hand numbness from carpal tunnel syndrome?

For mild numbness from carpal tunnel syndrome, moving the fingers may relieve it. If it doesn't help and the condition gets worse, surgery to cut a ligament in the wrist to relieve pressure might be needed. Eventually, the ligaments will grow back.

Is hand numbness a sign of aging?

Hand numbness is not a sign of aging in general but the “wear and tear” on your body as you get older can contribute to the symptom. Changes to the spine that come with normal living, such as arthritis or injury, can lead to cervical radiculopathy or "a pinched nerve," which can cause hand or finger numbness.

How do I know if hand numbness is related to a stroke?

Numbness can be one of the first signs of a stroke, but other signs would follow. Stroke symptoms can range from an inability to think or speak clearly to a sudden loss of vision or hearing.

A Word From Verywell

Most of the time, thumb numbness just results from compression of a peripheral nerve. While annoying, it isn't dangerous, provided no other warning signs are present. So long as the numbness is the only problem, no really aggressive treatment is generally called for.

Even if due to a stroke, healthcare providers may not give medication unless more serious symptoms are already present. A strong blood thinner can be given for stroke, but this increases the risk of bleeding in the brain, so it is used judiciously.

If the numbness in your thumb or other fingers persists, it's a good idea to visit your healthcare provider for an evaluation, but unless other signs of weakness or sudden onset are present, it's unlikely to be an emergency.

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By Peter Pressman, MD
Peter Pressman, MD, is a board-certified neurologist developing new ways to diagnose and care for people with neurocognitive disorders.