There are over 200 viruses that can cause the common cold, and infection of the upper respiratory tract. Symptoms include head congestion, sore throat, coughing, headaches, fever, restlessness, sneezing, etc. Because colds and flu are caused by viruses, antibiotics which are only effective against bacteria are of no use. Coughs are often due to an infection such as a cold or flu, asthma, chest infections and smoking.
Whether it's a cold or flu, get medical help if you have either: a chronic condition (such as asthma, diabetes or heart disease), or have a very high fever as well as an unusually severe headache or abdominal or chest pain.