Eosinophilic pneumonia is a rare type of pneumonia that affects the lungs. It is caused by a buildup of eosinophils, a type of white blood cell, in the lungs and blood, which can cause inflammation and damage. There are different types of eosinophilic pneumonia, including acute and chronic forms, and the exact cause of the disorder is often unknown (idiopathic) . However, causes can include smoking, allergic reactions, parasitic infections, certain medications or environmental triggers, and cancer. Symptoms of eosinophilic pneumonia can include cough, fever, difficulty breathing, and sweating at night. Treatment typically involves medications, such as corticosteroids, to ease symptoms and prevent respiratory failure. The prognosis is generally good once the condition is recognized and treated promptly.