The symptoms of mesothelioma may vary depending on the location of the mesothelium membrane that is affected. Symptoms of mesothelioma are characteristic of other illnesses and can only be definitively associated with mesothelium dysfunctions by a doctor. Most people are thought to have symptoms of mesothelioma 2 to 3 months before diagnosis. It is estimated that about one-forth of the people diagnosed have symptoms, at a minimum, 6 months before being diagnosed. In many cases, patients seeking assistance with other types of health issues, such as complications with pelvic mass, the gallbladder or a hernia, are later diagnosed with mesothelioma. The buildup of fluid characterizes all types of malignant mesothelioma. With pleural mesothelioma, patients will have fluid in the membrane that surrounds the lungs and chest cavity. This is known as pleural effusion. Patients with peritoneal mesothelioma will have fluid in the membrane that surrounds organs of the abdominal cavity. This is known as ascites. Patients with pericardial mesothelioma will have fluid in the pericardium membrane that surrounds the heart. This is known as pericardial effusion. The signs and symptoms of mesothelioma that develop in the membranes that surround the male (vaginalis testis) and the female (serosa uteri) internal reproductive organs are not fully understood. The only known symptom of vaginalis testis mesothelioma is a mass that may form in the groin. It is typically mistaken for a hernia.

Early symptoms of pleural mesothelioma are not easily recognized as symptoms of mesothelioma and are often dismissed as signs of overexertion or aging. Early symptoms of pleural mesothelioma include the following:

• Dry cough
• Fatigue
• Weight loss
• Night sweats
• Lumps of tissue under the skin near the chest

It may be months before early symptoms advance to acute symptoms, where pleural effusion occurs. Acute symptoms of pleural mesothelioma may include any of the following:

• Shortness of breath
• Painful breathing
• Pain in the lower back
• Pain at the side of the chest
• Chest pain under the rib cage
• Chest pain resulting from cancer tumors spreading outwardly and invading the chest wall.
• Shortness of breath resulting from effusion of the pleural.
• Trouble swallowing
• Fever
• Sweating
• Hoarseness
• Coughing up blood
• Swelling of the face
• Swelling of the arms
• Muscle weakness
• Sensory loss

Symptoms of peritoneal mesothelioma may include any of the following:

• Weight loss
• Abdominal pain
• Abdominal mass
• Abdominal distention
• Ascites (fluid) in the abdomen
• Abdominal swelling resulting from the build up of fluid
• Increased abdominal girth
• Fever
• Fatigue
• Obstruction of the bowels
• Frequent diarrhea
• Frequent constipation
• Lumps of tissue in the abdomen
• Anemia
• Blood clots
• Digestive complications

In general, the signs and symptoms of pericardial mesothelioma may include either of the following:

• Difficulty breathing
• Fever

If mesothelioma cancer metastasizes to other parts of the body, pain in the area where the cancer has spread, swelling of the face and neck or problems with swallowing may result.