A sore throat usually improves or goes away after a day or 2. Streptococcus bacteria (group A strep) causes strep throat. Strep throat is contagious and requires antibiotic treatment.

Bronchial tubes bring air from your nose and mouth into your lungs using your trachea (windpipe). When they become inflamed, these tubes can swell. The normal secretions that keep lungs moist and clean accumulate. Breathing passages constrict making it hard to keep lungs clear.

In the beginning, the flu can feel like the beginning of a cold with a runny nose, sneezing and sore throat. However, colds usually develop slowly, while the flu comes on rapidly.