Do You Have Nail Clubbing? What It Looks Like, and What It Means

Changes in the shape or feel of your nails can sometimes be a sign that something else is going on in your body. You may notice lines or grooves that weren’t there before. Or your nails may chip easily or feel brittle. 

Many of these changes can be normal. But nail clubbing is one type of change that may be a reason to see your healthcare provider. They can check to see if you have any of the conditions that commonly cause clubbing.

What is nail clubbing?

Nail clubbing is a change in the appearance of your fingernails or toenails. It more commonly affects the fingernails. And when it occurs, it usually affects both sides — left and right — of the hands or feet.

Scientists aren’t sure exactly what happens in the body that leads to nail clubbing. They think it has to do with decreased levels of oxygen in the blood. Lower oxygen causes a release of certain molecules in the blood. These molecules then lead to changes in the small blood vessels in the fingertips and toes. Scientists believe these blood vessels affect nail health. Changes in them can lead to the classic appearance of clubbed nails.

What do club nails look like?

Clubbed nails form when there is a change in the angle between the nail bed and the rest of the finger. 

In a normal fingertip, the area where the nail bed meets the finger is caved inward like a divot. In a clubbed nail, this area appears bulging like a mound. In other words, the inward angle becomes an outward angle. 

This causes the tips of the fingers and fingernails to look: 

• Swollen 

• More round 

• Wider

• Sponge-like or swollen

• Like a spoon turned upside down, with the bottom, curved side facing up

Stages of nail clubbing 

Nail clubbing occurs in different stages. But the differences can be subtle. Clubbing can develop quickly, over just a few weeks. 

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In early stages (after a few days or 1 week), you may notice:

• Softer or squishier nail beds

• A puffy appearance in the cuticle (the skin at the base of the nail)

In the later stages (after a week), you may notice:

• Increased curving of the nail, like an upside-down spoon 

• Redness of the skin around the nail

• Swelling of the fingertips or toes

• A shiny appearance of the nail or skin surrounding the nail

Clubbed nails vs. curved nails 

It can be hard to tell the difference between clubbed nails and curved nails. But there are things you can look for that can help.

Healthy nails grow with a slightly round curvature. So, if you look at the tips of your fingers or toes, each nail will look like the arch of a rainbow. 

But when nails curve in an abnormal way, the middle part of your nail is caved in and the sides are growing higher. The medical term for this is koilonychia. Curved nails (koilonychia) look like a divot in the middle of the nail. Clubbed nails look more like a mound.

What causes nail clubbing?

There are a few different causes of nail clubbing. They can be divided into three major categories:

1. Idiopathic nail clubbing: This means that there is no known reason as to what is causing the nail clubbing. And it is not a sign of an underlying medical condition.

2. Primary (inherited) nail clubbing: Some people inherit a gene that causes nail clubbing. While this is relatively rare, it’s more likely that you have this kind of clubbing if other people in your family have nails that look similar to yours.

3. Secondary nail clubbing: This means that there is an underlying medical condition that is causing the nail clubbing. Most often, these are heart or lung conditions that decrease the amount of oxygen that is in the blood.

Lung conditions that can cause clubbing include:

• Lung cancer: the most common cause of nail clubbing

• Cystic fibrosis: a genetic disorder that causes mucus to build up in the lungs

• Tuberculosis: a bacterial infection that commonly affects the lungs

• Asbestosis: a chronic lung condition caused by breathing in asbestos fibers in the air

• Interstitial lung disease: causes tissue in the lungs to swell and scar

• Chronic lung infections: regardless of what condition causes them

Heart conditions that can cause clubbing include:

• Congenital heart diseases: heart problems that are present at birth 

• Bacterial endocarditis: an infection of the heart valves 

• Myxoma: a tumor in the heart 

There are other conditions — outside the heart and lungs — that can cause nail clubbing. These include: 

• Celiac disease

• Liver disease

• Inflammatory bowel disease 

• Thyroid disease

Remember, nail clubbing is not always a sign of a medical problem. But if you notice this new change in your nails, reach out to your provider. They can help run tests to figure out if any of these conditions are the reason that you have clubbed nails.

Can you reverse nail clubbing?

If you have a medical condition causing nail clubbing, you can reverse it by treating the underlying medical condition. The clubbing should go away over time.

But this isn’t true if you inherit nail clubbing — or if it develops for no reason. In these cases, the clubbing cannot be reversed or treated. But nail clubbing on its own generally doesn’t require treatment.

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Written by:

Cherilyn Davis, MD

Cherilyn Davis, MD, is a board-certified pediatrician in New York City. She has held local and national roles at the American Medical Women’s Association including board member of the physician division and physician chair of social media.

Edited by:

Katie E. Golden, MD

Katie E. Golden, MD, is a board-certified emergency medicine physician and a medical editor at GoodRx.

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