A sore throat, or pharyngitis, is when the throat is red, swollen and painful, especially when you swallow. It happens when the back of the throat, called the pharynx, is inflamed. Usually, sore throats go away without treatment within 3 to 4 days. Seek medical attention if: you have trouble breathing or swallowing (or if your baby is drooling) you have a stiff or swollen neck you have a high fever you have a rash you feel very unwell or the sore throat is getting worse