What Are the Complications of Lung Cancer?
Updated on June 16, 2026
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Lung cancer and the therapies used to treat it can cause a number of complications that affect breathing, blood flow, and quality of life. Lung cancer tumors can block the airways, put pressure on nerves and organs, and release hormones or chemicals that impact how well the body functions.
These are some of the most common lung cancer complications and the symptoms to discuss with your doctor.
Breathing Problems
The lungs are the body’s breathing organs. They pull oxygen from the environment into the blood vessels to be transported around the body. Lung cancer can lead to several common types of breathing problems.
Shortness of Breath
Shortness of breath, also called dyspnea, is often described as a tightness in the chest or the feeling that you’re unable to catch your breath. This may happen during exercise, at rest, or all the time.
Lung cancer causes shortness of breath in a few ways. A tumor can grow large enough to narrow or block an airway, preventing enough oxygen from getting into the body. The cancer could also lower your total amount of red blood cells, which carry oxygen around the body. Having too few red blood cells means your heart and lungs must work harder, leading to shortness of breath.
Some treatments, such as lung cancer surgery and radiation, can cause shortness of breath as well. Breathing might improve as you recover, but in some cases it can be a long-term issue.
Doing breathing exercises, eating a nutritious diet, and quitting smoking can help relieve breathlessness. Supplemental oxygen is an option for people who are very short of breath. Sometimes procedures like bronchoscopy can be used to open up an airway blockage and improve breathing.
Shortness of breath can be serious. Get medical help right away if it starts suddenly, it’s severe, or you also have chest pain.
Pleural Effusion
Pleural effusion is an abnormal collection of fluid in the space between the pleura, the thin membrane that covers the lungs and lines the interior wall of the chest cavity. Malignant pleural effusion occurs when cancer cells also build up in this space.
Shortness of breath, chest pain, and cough are common symptoms of pleural effusion. Doctors diagnose this condition with X-ray, computed tomography (CT) scan, or ultrasound of the chest.
Without treatment, pleural effusion can cause scarring, lung damage, and sometimes an infection. The main treatment for pleural effusion is an outpatient procedure called thoracentesis, in which a doctor places a needle into the pleural space to drain the fluid. Chemotherapy and other medicines can destroy cancer cells in the pleura.
Coughing Up Blood
Coughing up red or rust-colored phlegm can be a sign of lung cancer. Doctors call this hemoptysis, and it may occur because of a ruptured blood vessel in the tumor, a clot, or infection in the lung. This is a serious symptom that needs treatment. If the bleeding is severe, blood could spill over into the healthy lung and cause aspiration.
The first step in treatment is to find the source of the blood to control the bleeding. A number of minimally invasive procedures, such as a bronchial artery embolization, can block the bleeding.
Heart and Blood Issues
Lung cancer and cardiovascular disease (CVD) are closely connected. They share risk factors like high blood pressure, obesity, diabetes, and tobacco smoking. Inflammation contributes to both lung cancer and heart disease, and cancer promotes the release of inflammatory substances that contribute to CVD.
For these reasons, people with lung cancer are at higher risk for coronary artery disease, heart attack, and stroke. The following heart complications are also possible.
Pericardial Effusion
Pericardial effusion is a buildup of fluid in the pericardium, the pouch that surrounds the heart. The extra fluid puts pressure on the heart and prevents it from expanding enough to fill with blood and pump it out to the body.
Pericardial effusion can happen when the tumor grows into lymph nodes in the chest. The cancer blocks drainage in the lymph system, which causes fluid to collect. Lung cancer treatments like chemotherapy, radiation therapy, and immunotherapy sometimes cause pericardial effusion as a side effect.
Call your doctor about symptoms like shortness of breath, chest pain, fast heartbeat, dizziness, or a blue color to your lips. Without treatment, pericardial effusion can lead to cardiac tamponade, a life-threatening condition in which the heart stops beating. The main treatment for pericardial effusion is pericardiocentesis, which removes fluid from the pericardium.
Superior Vena Cava Syndrome (SVCS)
The superior vena cava (SVC) is a large vein in the chest that carries blood from the head, neck, and arms to the heart. When a tumor presses on the SVC, it narrows the vein and slows blood flow.
SVCS is dangerous because it causes blood to back up in the SVC and can lead to life-threatening symptoms. Get medical help if you experience the following:
- Enlarged veins in the neck or chest
- Swelling in the face, neck, upper chest, or arms
- Blurred vision
- Headache
- Dizziness or fainting
- Shortness of breath
Treatment for SVCS includes radiation therapy, chemotherapy, or surgery to remove the tumor. Placing a small tube called a stent inside the SVC keeps the vein open to improve blood flow.
Blood Clots
Having cancer, especially lung cancer, increases the risk for blood clots. One reason is that cancer cells produce chemicals that make platelets stickier and more likely to form clots. Some cancer medications, including chemotherapy and immunomodulatory drugs, also raise the risk of blood clots.
Signs of a blood clot in the leg, called deep vein thrombosis (DVT), include swelling on one or both of the legs, pain or tenderness in the area, and red or discolored skin. When the clot travels to the lungs and blocks blood flow, it’s called pulmonary embolism (PE), which can be life-threatening. Signs include breathlessness, chest pain, and dizziness. Blood-thinning drugs stop the clot from getting larger while your body naturally breaks it down. In severe cases, surgery may be needed to remove the clot.
Hypercalcemia
Hypercalcemia is high calcium levels in the blood. Having too much of this mineral can weaken bones, damage the kidneys, and cause an abnormal heart rhythm. Lung cancer, especially late-stage cancer, increases the risk for hypercalcemia.
Symptoms include:
- Extreme thirst
- Frequent urination
- Stomach pain
- Bone pain
- Muscle weakness
- Vomiting
- Constipation
- Confusion
- Drowsiness
Some people with hypercalcemia need treatment with IV fluids in a hospital to lower calcium levels. Medications like bisphosphonates, denosumab, and calcitonin are another way to bring down calcium levels in the blood and preserve bone strength.
Other Complications
Lung cancer can cause other complications as it grows and spreads. These are a few of the most common ones.
Frequent Infections
People with any type of cancer are at increased risk for infections. Both cancer and treatments like chemotherapy and immunotherapy weaken the immune system, making it less able to fight off germs.
Additionally, when a tumor blocks the airway, bacteria and viruses can get trapped inside the lungs. That’s why people with lung cancer are at higher risk for respiratory infections like pneumonia and bronchitis. A cough, fever, chills, and body aches are symptoms of these lung infections.
Bone Pain and Fractures
Bones are one of the most common sites where lung cancer spreads. The medical term for cancer in the bone is bone metastasis. Cancer weakens the bones, sometimes to the point where they fracture.
Nerve Pain
A tumor that presses on nerves can cause nerve damage called peripheral neuropathy. This feels like pins and needles, burning, or mild-to-severe pain. Surgery and some chemotherapy drugs can also damage nerves.
Spinal Cord Compression
Sometimes lung cancer spreads to the spinal cord and puts pressure on nerves around it. This is called metastatic spinal cord compression (MSCC). Symptoms include pain, numbness, weakness, and difficulty controlling your bladder. Quick medical attention is needed to minimize damage to the spinal cord. Treatments include radiotherapy, chemotherapy, steroids, and surgery.
EDITORIAL SOURCES
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Resources
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- Deep Vein Thrombosis. Cleveland Clinic. December 23, 2025.
- Hypercalcemia. Mayo Clinic. March 8, 2024.
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- Why Are People With Cancer More Likely to Get Infections? American Cancer Society. February 13, 2024.
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Tingting Tan, MD, PhD
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Tingting Tan, MD, PhD, is a medical oncologist at City of Hope National Medical Center.
Dr. Tan's research has been published in multiple medical and scientific journals, including...
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