The most common type of viral disease is the common cold, which is caused by a viral infection of the upper respiratory tract (nose and throat).
Other common viral diseases include: Chickenpox, Flu, Measles and Shingles.
Viral diseases are contagious and spread from person to person when a virus enters the body and begins to multiply.
Viral diseases are not treatable with antibiotics, which can only cure bacterial diseases and infections. However, the most common viral diseases, the common cold and the flu, are self-limiting in generally healthy people.
In some cases, viral diseases can lead to serious, possibly life-threatening complications. People at risk of complications include those who have a chronic disease or a suppressed or compromised immune system, and the very young and very old.
If you are unwell, unsure, confused or need medical advice, contact your GP surgery or call NHS 111 to speak to a trained adviser who will direct you to the best medical care for you. Remember 111 is also the number to call for the GP Out-of-hours service.
You can also can also find more information on the NHS Choices website.
Call 999 if you someone you are with has a serious symptom of an illness or a viral disease, such as shortness of breath, chest pain, blacking out (fainting), or when there is a change in alertness or consciousness.