Most common upper respiratory infections (URI) are caused by viruses, not bacteria. So antibiotics will not be helpful, and may be detrimental. The human immune system is very efficient in clearing most infections. The most common viral infections include colds, flu, upper respiratory infections, sinus and ear infections, and sore throats.
Do not be surprised if your doctor does not recommend an antibiotic to treat conditions caused by viruses, like those mentioned above. He or she will help you control the symptoms of your illness and tell you what to do should you not get better.
Over the years some bacteria have become resistant to antibiotics. This is felt to be due in part to antibiotics being inappropriately used to treat viral infections.
Each type of antibiotic only works against certain types of bacteria. This is why different types of antibiotics are used to treat different types of infections. There are other factors that influence the choice of medication as well. The severity of your illness, status of your kidney and liver function, other medications you may be taking and other health conditions will influence the doctor’s decision to prescribe an antibiotic or which antibiotic to use to combat your infection.