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Finger clubbing — which includes swelling of the fingertips and changes to the appearance of fingernails — is a common symptom of lung cancer: Around 80 percent of people with finger clubbing have lung cancer. Sometimes called “clubbed fingers,” finger clubbing may run in families as a harmless trait. It may also be an indication of heart, liver, or other lung disorders.

This article will cover what finger clubbing looks like, its causes, and when to see your health care provider.

What Does Finger Clubbing Look Like?

People with finger clubbing may have:

• Bulging fingertips

• Soft nail beds with fingernails that don’t look firmly attached

• Fingernails that angle sharply at the cuticle (base of the fingernail)

• Fingernails that curve downward around the fingertips

Finger clubbing usually occurs slowly, so you may not initially notice it’s happening.

If you do see anything early on, it may be reddening and softening of the nail bed (the soft skin underneath your nails). If you touch your nails, they might also feel spongy.

Eventually, your nails will have a downward curve and a shiny appearance. You might also notice an enlargement of your fingertips.

How Can I Check for Finger Clubbing?

Since clubbed fingers can take many years to develop, it may be hard to notice. You can check for the Schamroth sign to see if your fingers have become clubbed.

Checking for the Schamroth sign entails placing the nails of both index fingers together up to the last joint as if you’re forming the top of a heart shape. You should be able to see a diamond-shaped window of space form between your nails and the joints closest to your fingertips. If you don’t see this space, then you might have finger clubbing.

What Causes Finger Clubbing?

In 80 percent of cases of clubbed fingers, lung cancer is the cause. It may be linked to low oxygen, which can occur in lung cancer and other conditions. In lung cancer, finger clubbing is thought to be associated with excessive amounts of growth factors that encourage the growth of blood vessels.

However, some lung cancer treatments and comorbidities (other health conditions you may have at the same time) can also contribute to nail or finger changes.

Lung Cancer Treatments and Finger Clubbing

Some lung cancer treatments may cause nail or finger changes. Some of these may look similar to finger clubbing, but they’re not symptoms of finger clubbing.

The following are some medications used to treat lung cancer that can cause nail changes and swelling of your fingertips:

• Albumin-bound paclitaxel (Abraxane)

• Cisplatin (Platinol)

• Docetaxel (Taxotere)

• Doxorubicin (Adriamycin)

• Erlotinib (Tarceva)

• Gemcitabine (Gemzar)

• Methotrexate (Trexall)

• Osimertinib (Tagrisso)

• Paclitaxel (Taxol)

Lung Cancer Comorbidities and Finger Clubbing

Some comorbidities of lung cancer are linked to clubbed fingers. Some of these other medical conditions include:

• Infective endocarditis (heart infection)

• Chronic lung infections, such as bronchiectasis or cystic fibrosis

• Other infections, such as HIV

• Liver disease

• Other cancers such as liver cancer or Hodgkin lymphoma, a type of blood cancer

How Lung Does Finger Clubbing Last?

Finger clubbing can be a temporary or a long-term symptom depending on what’s causing it. If it’s caused by a health condition, treating the condition may reverse the finger clubbing. If finger clubbing is the result of a chronic condition or cancer, clubbing may be long term or permanent.

What Does Finger Clubbing Tell Your Health Care Provider?

Clubbed fingers typically don’t require treatment, but it’s good to let your health care provider know if you develop this symptom since clubbed fingers can be connected to serious medical conditions.

If you notice a downward curve in your fingernails and swelling in your fingertips, notify your health care provider, who will physically examine your fingers. They may ask about other symptoms and order some blood and lab tests to diagnose or rule out health conditions that may be causing clubbed fingers.

ABOUT THE AUTHOR:

Ross earned her doctorate in pharmacy (PharmD) at The University of Texas at Austin (UT Austin). Her years of experience practicing in various pharmacy settings also lead to multiple board certifications, including ambulatory care, geriatrics, and pharmacotherapy. She currently serves as the director of the PharmacyChecker international verification program.

Ross also founded Off Script Consults, a pharmacy consulting business. She strives to combine her passion for pharmacy, education, and writing to improve the quality of life and financial outcomes for people with chronic medical conditions, caregivers, and healthcare providers.

She particularly enjoys creating relatable and helpful content for her readers and viewers. For writing samples, please visit her Muck Rack portfolio. For videos, please visit her “Off Script Consults” YouTube channel.

Ross currently resides with her husband and two dogs in her home state of Texas to be closer to family. She also tries to find time for hobbies, which include rock climbing, running, and playing pickle ball.

Find out more about Ross via phone, e-mail, or social media (LinkedIn, TikTok, Instagram, Twitter, Facebook, and Pinterest).