The symptoms of respiratory infections vary among individuals. Common clinical symptoms include fever, headache, fatigue, swollen throat, coughing, runny nose, sneezing, tearing, as well as difficulty breathing, phlegm, chest pain, and body aches. Some may also experience nausea, vomiting, and even sleep disturbances. Severe cases can lead to oxygen deprivation due to inflammation, manifesting as cyanosis of the lips, and increased and rapid breathing.