If you or someone you love is coughing up black phlegm (also called mucus or sputum), it’s natural to feel anxious. After all, black is an unusual color for phlegm, and seeing it is likely to make you wonder what is going wrong with your body or your loved one’s.

Although black phlegm can be an indication of lung cancer, there are several other potential causes for coughing up dark-colored phlegm. Here’s what you need to know to decide what steps to take next.

Black Phlegm and Lung Cancer

Coughing up black phlegm can be a sign of lung cancer. If you haven’t been diagnosed with lung cancer, reach out to your doctor. Also, look for other common symptoms of lung cancer, such as:

• Chest pain
• A persistent cough that doesn’t go away
• Coughing up blood
• Shortness of breath
• Fatigue, even when well-rested
• Unexplained weight loss

If you notice any of these signs, inform your doctor when discussing your black phlegm.

Black phlegm may occur if a lung cancer tumor restricts blood circulation to part of your lungs. Without blood flow, that tissue will die. You may then cough up that tissue, and it can appear as black phlegm.

Black Phlegm and Metastatic Melanoma

Another type of cancer, called melanoma, can metastasize (spread) to your lungs. This specific type of cancer is likely to produce black phlegm. The lungs are rarely the first place where melanoma shows up in the body. In these cases, it did not spread from anywhere else.

Melanoma may spread to the lungs, but it’s still melanoma, not lung cancer. Therefore, it’s diagnosed and treated differently. If you know you have melanoma or have had it before, make sure you mention it when speaking to your doctor about your black phlegm.

What Else Causes Black Phlegm?

There are several other potential causes for black phlegm.

Smoking

Smoking is one of the main causes of black phlegm. Inhaling the chemicals in cigarettes can cause the buildup of a substance called sticky tar in the lungs. This dark substance shows up on the chest X-rays of people who smoke. If you cough any of this up, it can make your phlegm black.

Smoking marijuana can also damage your lungs. Research is ongoing about the specific effects of marijuana, but it may also cause black phlegm because it contains many of the same chemicals as cigarettes.

Exposure to Some Chemicals

Inhaling certain substances can also cause black phlegm. This most frequently happens to people working in environments where they’re regularly exposed to certain chemicals or substances, though any smoke can harm your lungs.

If you regularly inhale coal dust — or other dark substances, like dirt or even dust — you may be more likely to develop dark phlegm. Depending on where you live, you may also inhale these and other dangerous substances via air pollution. Consider investing in protective devices, like masks, to safeguard your lung health.

Fungal Infection

A certain type of fungal infection called “Exophiala dermatitidis” can also cause black mucus. This type of fungal infection is rare and occurs most frequently in people with compromised immune systems. If your immune system is compromised from chemotherapy or other factors, inform your health care provider when discussing your black phlegm.

Other Conditions

Various other medical conditions or lung diseases can cause your lungs to produce black phlegm. These include:

• Some types of pneumonia
• Chronic obstructive pulmonary disease (COPD)
• Cystic fibrosis
• Tuberculosis
• Bronchiectasis (a condition in which the airways are wider than normal, leading to a buildup of mucus)

You can be diagnosed with any of these conditions in addition to lung cancer. You can also experience them entirely separately from that. You and your doctor will need to work together to make sure you find the source of your black phlegm.

Talk to a Doctor if You’re Concerned

If you or your loved one has been diagnosed with lung cancer, new or changing symptoms may develop throughout the condition. By keeping your health care team updated on symptoms such as coughing up black phlegm, you can help ensure that your treatment plan is as effective as possible in treating your lung cancer and managing symptoms that impact your quality of life.

If your coughing intensifies or the amount of phlegm you produce increases, inform your doctor. It’s also essential to notify your doctor if the color of your phlegm changes. Keeping your medical team updated on your symptoms can help catch complications of lung cancer before they cause major issues. If you experience difficulty breathing or chest tightness, inform your doctor immediately or seek emergency care.

If you haven’t been diagnosed with lung cancer and you notice black phlegm, consult your doctor as soon as possible. They will determine what conditions to test for, likely including lung cancer. Your health care team will ensure you receive the necessary diagnosis to treat the underlying cause of the black phlegm. Your doctor can also help you manage related symptoms, such as cough.

Find Your Team

On MyLungCancerTeam, the social network for people with lung cancer and their loved ones, more than 12,000 members come together to ask questions, give advice, and share their stories with others who understand life with lung cancer.

Have you or a loved one coughed up black phlegm? Share your experience in the comments below, or start a conversation by posting on your Activities page.