The common cold

Respiratory infections

The “common cold” is a viral infection. In more than two thirds of people, the germ responsible is a small virus called rhinovirus. It remains the most prevalent contagious disease in this country. It is the most cited reason for absence from school or work, and the most common reason for a visit to a family doctor.


The common cold is caused by a tiny germ called a virus. Viruses are so small they can pass through fine filters that can stop larger germs such as bacteria. These are spread from person-to-person in the small drops produced during coughing and sneezing. They can also be passed by hand-to-hand contact after touching infected noses and eyes.

Cold viruses usually infect the nose, throat and lungs with little or no fever. Individuals differ in the number of symptoms they have. Over 100 different viruses can cause a common cold. There is often more than one strain circulating in the community at any one time.


Colds have many other names such as upper respiratory tract infection. Other names simply refer to that part of the body affected such as the eyes (conjunctivitis), nose (rhinitis), sinuses (sinusitis), throat (pharyngitis), voice box or larynx (laryngitis) and the air tubes in the lungs (bronchitis).

Certain respiratory viruses circulate within the community at certain times of the year. Rhinovirus is a particularly common virus causing the vast majority of colds. In children, it may cause croup, whereas in adults, it can cause a troublesome illness dominated by cough. Other viruses circulate in the community in spring and autumn. Whilst they usually cause mild common cold symptoms, they can progress to more severe illness and problems involving the lungs.

Who is at risk?

Colds are a common viral illness that can affect anyone. It’s normal for young children in day care, pre-school and primary school to experience frequent colds – between 5 and 10 per year.

Colds are caused by a virus spread by another infected person. A number of conditions can increase your chances of catching a cold. People appear to catch colds indoors during the colder months when living conditions bring people closer together and close to other people’s cold viruses. Closed windows and lack of fresh air also seem to contribute to the problem. Fatigue, poor health, some indoor air pollutants and stress may also increase susceptibility. Cold weather, chills or exposure to cold do not cause colds. Stress and cigarette smoking reduce resistance to infection and make symptoms more severe.


Cold symptoms usually appear from one to four days after the virus enters the body. The cold can be spread to others even before any symptoms appear. Symptoms usually begin with an itchy or sore throat. This is followed by a stuffy blocked nose, sneezing and watery eyes. Within two days, other symptoms may develop including a runny nose, husky voice, muscle aches and pains and headache. Fever occurs in children but is rare in adults. Symptoms then gradually improve.

Can a cold be dangerous?

The majority of colds will clear up in a week or so. Some colds open the door to other illnesses. Bacterial infections may gain the upper hand when your defences are down. Bacterial infection may develop in the ears, sinuses, airways and lungs. People with other lung problems such as asthma, Chronic Obstructive Pulmonary Disease (COPD), bronchiectasis and cystic fibrosis are at considerable risk and should be closely monitored.


A common cold cannot be cured by current treatments – the body cures itself! Antibiotics only attack bacteria, they have no effect on the cold virus and should not be used. Antihistamines and decongestants clear nose, sinus and ear congestion. Paracetamol can relieve muscle aches and pains and reduce fever. Nasal decongestant sprays may be useful when your nose is blocked. Long term use of these medications is not recommended, unless advised by your doctor. Throat lozenges, many containing menthol or eucalyptus, are freely available. They are not suitable for young children. Some of these medications have side effects, so ask your doctor which one(s) he/she recommends.

Avoid touching your nose and wash your hands frequently. Stay hydrated by drinking water to keep your nose, throat and air tubes moist. Eat well balanced meals and get plenty of rest. This conserves energy and may help to avoid complications. Bed rest for 1-2 days may shorten the duration and severity of the cold.

If you have asthma or COPD and have an increase in symptoms, see your doctor without delay. Ask your doctor about an Action Plan so you are prepared for the next time you get a cold.


Keep your distance from people who have colds, especially if they cough or sneeze. Cover your own coughs and sneezes with a disposable paper tissue.  A healthy lifestyle and diet, not smoking and exercise will all help. Make sure to practice good hand hygiene to minimise the spread of germs.