What Are the Symptoms of Mesothelioma?

Pleural Mesothelioma Symptoms (Lungs and Chest)

Pleural mesothelioma is the most common form, accounting for roughly 75% of all cases. It develops in the lining of the lungs (the pleura) and produces symptoms that are often mistaken for pneumonia, COPD, or other respiratory conditions.

The most common pleural mesothelioma symptoms include:

• Chest pain — often felt in the lower back or side of the chest, worsening over time
• Shortness of breath (dyspnea) — caused by fluid buildup or tumor growth restricting lung expansion
• Persistent dry cough — unresponsive to typical cough treatments
• Pleural effusion — fluid accumulation between the lung and chest wall, which can cause pressure and breathing difficulty
• Unexplained weight loss — often 10 or more pounds without dietary changes
• Fatigue — persistent tiredness not relieved by rest

According to the American Cancer Society, pleural effusion is present in the majority of pleural mesothelioma patients at the time of diagnosis. This fluid buildup is often the symptom that first prompts medical evaluation.

Peritoneal Mesothelioma Symptoms (Abdomen)

Peritoneal mesothelioma develops in the lining of the abdominal cavity (the peritoneum) and accounts for approximately 15 to 20% of cases. Its symptoms are frequently confused with irritable bowel syndrome, hernias, or other gastrointestinal conditions.

Common peritoneal mesothelioma symptoms include:

• Abdominal pain or tenderness — often diffuse rather than localized
• Abdominal swelling or distension — caused by ascites (fluid buildup in the abdomen)
• Nausea and vomiting
• Unexplained weight loss and loss of appetite
• Bowel changes — constipation or diarrhea
• Abdominal lumps — in some cases, masses can be felt through the skin

Pericardial Mesothelioma Symptoms (Heart)

Pericardial mesothelioma is extremely rare, accounting for less than 1% of all mesothelioma cases. It develops in the pericardium, the thin sac surrounding the heart. Symptoms may include chest pain, irregular heartbeat (arrhythmia), difficulty breathing, and pericardial effusion (fluid around the heart). Due to its rarity and nonspecific symptoms, pericardial mesothelioma is frequently diagnosed only after death.

The Latency Period: Why Symptoms Appear Decades Later

One of the most challenging aspects of mesothelioma is its long latency period. According to the National Cancer Institute, symptoms typically appear 20 to 50 years after the initial asbestos exposure. This means a worker exposed to asbestos in the 1970s or 1980s may not develop symptoms until the 2020s or later.

This extended latency period is one reason mesothelioma is often diagnosed at an advanced stage. Many patients do not connect their current symptoms to workplace asbestos exposure that occurred decades ago. Anyone with a history of asbestos exposure who develops respiratory or abdominal symptoms should inform their physician about that exposure history.

Early-Stage vs. Late-Stage Symptoms

Early-stage symptoms (stages I and II) tend to be mild and nonspecific. Patients may experience slight chest discomfort, mild shortness of breath during exertion, or a low-grade cough. These early symptoms are frequently attributed to age, smoking history, or minor respiratory infections, which delays diagnosis.

Late-stage symptoms (stages III and IV) are more severe and debilitating. They may include significant difficulty breathing even at rest, severe chest or abdominal pain, difficulty swallowing (dysphagia), lumps under the skin on the chest, night sweats, fever, and muscle weakness. At advanced stages, the cancer may spread to other organs, causing additional symptoms depending on the sites of metastasis.

When to See a Doctor

You should see a doctor promptly if you experience any combination of the symptoms listed above, especially if you have a history of asbestos exposure through your occupation, military service, or living environment. Key warning signs that warrant immediate medical attention include:

• Persistent chest pain or shortness of breath lasting more than two weeks
• Unexplained weight loss of 10 pounds or more
• Abdominal swelling that does not resolve
• A persistent cough that worsens or does not respond to treatment

When speaking with your physician, be specific about your asbestos exposure history, including the dates, locations, and types of work you performed. This information helps doctors consider mesothelioma in their differential diagnosis rather than attributing symptoms to more common conditions.