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Colds & flu explained

Find out the difference between colds & flu

What is flu?

Although the common cold and flu share similar symptoms, they are quite different infections. Flu is caused by a specific group of viruses known as the influenza virus. However, there are a number of different strains, such as swine flu and avian flu (also known as bird flu), with more forming as the virus mutates.

This is why people continue to come down with the flu each year and that there is the need to renew the flu vaccination each winter. Symptoms of flu are usually more severe than with colds. Additional symptoms may also be experienced - fever, nausea, chills and sweats, headache, aching muscles and loss of appetite.

The flu virus can be spread from one person to the next from day one and before symptoms appear. Hence, it is possible to spread the flu before one notices symptoms. 

Who catches colds and flu?

Anyone who is at risk from colds and flu and these infections can come at any time of the year. In the UK and Ireland, peak season for these infections is during the autumn or winter months. There is usually a small peak during early spring and one particular type of cold virus thrives in the summer.

Those with weaker immune function (due to illness, stress, lifestyle habits) are more likely to catch a cold or flu than the average healthy adult.

How do cold and flu viruses spread?

The most common route for viruses causing colds and flu to spread is from ‘hand to nose’. Touching a surface infected with viruses (door handles, escalator rails or shaking hands with someone with the cold) passes it to your mouth, nose or eyes. Just observing how often people touch their faces will give you a clue as to how easily viruses can spread in this way.

Another way which infective viruses spread is in droplets produced when sneezing or coughing. It may surprise you that this is not as efficient in spreading infection compared to the ‘hand to nose’ route.

What is the immune system?

The immune system exists to protect our body against infection. It is made up of special blood cells, proteins, organs and other tissues - all designed to defend and support our body against invading organisms. Put another way, it is the army protecting the body against infection by viruses, bacteria and fungi, keeping us healthy and free from infections. 

What if you have a weakened immune system?

Weak immune function makes it more difficult for the body to withstand infection, so an early sign of a weak immune system is a tendency for the body to pick up infections such as colds and flu.

This happens because a poorly functioning immune system can’t spot the nasty invaders efficiently. In addition, the immune system may also take longer to overcome bugs.

The common cold

Colds are probably the most common of all infections experienced by people in the Western world. On average, adults can expect to get 2 or 3 colds a year and children even more. Each can last up to a week.

Colds are caused by many different viruses - there are over 200 which are known to cause the common cold. The corona virus and rhinovirus are amongst the two most often found. Symptoms of the common cold are familiar to most of us and include:

  • Blocked or runny nose
  • Sneezing
  • Sore throat
  • Cough
  • Tiredness
  • Headaches

What to look out for

Colds are not usually considered to be serious illnesses and most people either ignore the problem or use home remedies to treat the condition. Only 5% of people in the UK visit their doctor for help with the common cold. If you are fit and have a healthy immune system, it is fine to manage the symptoms of colds or flu yourself. Many people use herbal remedies such as Echinacea to support their immune system.

However, there are some people who need to take extra care. Those suffering from asthma, bronchitis, or those with a weak immune system often need extra support and attention. The very young or the elderly may also find that their immune systems are not strong enough to fight off infections, so care must also be taken with this group of people. As with any illness, see your doctor if you are worried or in doubt.

Finally, remember that there are many ways you can help support the immune system - see our Tips to help stay healthy and prevent colds.