Patients with pneumonia usually have a cough, fever or chills, dyspnea, weakness and loss of appetite. Sometimes, some patients may also have nausea, diarrhea and/or chest pain. However, some patients with pneumonia may also not have a cough or fever. Symptoms may appear quickly or may get progressively worse over time. Sometimes, patients with viral upper respiratory tract infections (colds), develop a new manifestation of fever and exacerbation, which often signals the beginning of a secondary bacterial infection.