Pneumonia is not a symptom of ALS in and of itself; however, it stands as one of the most common and deadly complications of the disease.
Pneumonia is a respiratory infection that causes severe inflammation of the pulmonary alveoli, usually caused by bacteria or viruses. It is characterized by general malaise, a fever that is frequently preceded by chills, severe shortness of breath, productive cough, and chest pain. Pneumonia cough is commonly accompanied by yellowish sputum that may present traces of blood. If not treated effectively, pneumonia presents a risk of death.
In the case of patients with ALS, the evolution of pneumonia is complicated by the respiratory deficit already present as a consequence of the disease, the weakness of the chest muscles involved in breathing, and the difficulty, or outright inability, to expel the phlegm and mucus generated by the infection.