Influenza and the Common Cold

Colds and flu are both common respiratory infections, but they are caused by different viruses and flu usually causes more severe symptoms. A cold tends to develop gradually and mainly affects the nose and throat, while flu can come on quickly and leave you feeling exhausted and too unwell to carry on with normal activities.

Although they share some symptoms, understanding the differences between a cold and flu can help you decide how best to look after yourself and when you may need medical advice.

Contents

• What is influenza?
• What is a cold?
• What causes colds and flu?
• How are colds and flu spread?
• Cold and flu symptoms
• Flu immunisation
• How is flu diagnosed?
• Treating colds and flu
• When to seek medical advice
• Possible complications
• How to reduce your risk

What Is Influenza?

Influenza, usually called flu, is a viral infection of the respiratory system. It is highly infectious and can spread easily from one person to another.

Flu symptoms often appear very quickly, sometimes within a few hours. They can include a sudden high temperature, aching muscles, tiredness or exhaustion, a dry cough, sore throat, headache, loss of appetite and difficulty sleeping.

Some people recover relatively quickly, while others may feel unwell for longer. Flu can also cause serious complications in people who are more vulnerable to infection.

What Is a Cold?

The common cold is also a viral respiratory infection, but it is caused by a wide range of different viruses. This is one reason why there is no vaccine that protects against the common cold.

Cold symptoms usually appear gradually over two or three days and mainly affect the nose and throat. A blocked or runny nose, sneezing, sore throat and cough are particularly common.

Most people can treat a cold at home without seeing a GP. According to the NHS, you should normally begin to feel better within around one to two weeks, although symptoms can last longer in young children.

What Causes Colds and Flu?

Both colds and flu are caused by viruses, but they are not the same infection. Many different viruses can cause a common cold, while flu is caused by influenza viruses.

Influenza viruses change over time, which is one reason the flu vaccines used each year are updated to protect against the strains expected to be circulating.

Because colds and flu are viral infections, antibiotics do not treat the viruses themselves. Antibiotics are only effective against bacterial infections.

How Are Colds and Flu Spread?

Cold and flu viruses can spread when an infected person coughs or sneezes, releasing droplets containing the virus. They can also spread through contaminated hands and surfaces.

For example, you may pick up a virus by touching a contaminated object and then touching your eyes, nose or mouth. Regular hand washing and good respiratory hygiene can therefore help reduce transmission.

Viruses responsible for colds and flu can survive on hands and surfaces for a period of time, so it is sensible to clean frequently touched objects and avoid sharing personal items with someone who is unwell.

What Are the Symptoms of Influenza and a Cold?

Cold and flu symptoms can overlap, but flu generally develops more quickly and tends to make you feel significantly more unwell.

Common cold symptoms

• Blocked or runny nose
• Sneezing
• Sore throat
• Hoarse voice
• Cough
• Feeling tired or generally unwell
• Occasionally a raised temperature or aching muscles

Common flu symptoms

• Sudden high temperature
• Aching muscles or body
• Feeling tired or exhausted
• Dry cough
• Sore throat
• Headache
• Difficulty sleeping
• Loss of appetite
• Feeling hot, cold or shivery

A useful general distinction is that a cold may leave you feeling unwell but still able to carry on with many normal activities. Flu is more likely to leave you exhausted and unable to continue your normal routine.

Flu Immunisation

The flu vaccine helps protect against influenza and is offered by the NHS every year during autumn and winter to people at greater risk of becoming seriously ill from flu.

Adults who may be eligible for a free NHS flu vaccination include people aged 65 and over, people with certain long-term health conditions, pregnant women, people living in care homes, some carers and people who live with someone who has a weakened immune system. Frontline health and social care workers may also be offered vaccination through their employer.

Flu vaccination is also offered to many children, including children aged two or three, school-aged children and younger people with certain long-term health conditions.

The groups offered an NHS flu vaccine can change, so check the latest NHS flu vaccine guidance if you are unsure whether you or a family member is eligible.

The influenza viruses targeted by the vaccine are reviewed regularly and protection reduces over time, which is why eligible people are advised to have the flu vaccine each year.

How Is Flu Diagnosed?

Flu can often be recognised from the pattern and severity of symptoms, particularly when influenza is circulating widely in the community. In most uncomplicated cases, laboratory testing is not needed.

Testing may sometimes be used in hospitals or other clinical settings where confirming the cause of a respiratory infection could affect treatment or infection-control decisions.

What Treatment Is There for Colds and Flu?

Most colds and uncomplicated cases of flu can be managed at home. Resting, drinking plenty of fluids and taking suitable medicines for pain or fever can help relieve symptoms while your body recovers.

Helpful measures can include:

• Getting plenty of rest
• Drinking enough water and other non-alcoholic fluids
• Avoiding smoking
• Taking paracetamol or ibuprofen if these medicines are suitable for you
• Using throat lozenges or warm drinks to soothe a sore throat
• Speaking to a pharmacist about suitable over-the-counter cold and flu remedies

Be careful not to take more than one medicine containing paracetamol at the same time. Some combined cold and flu remedies already contain paracetamol.

Antibiotics do not treat cold or flu viruses and will not make an uncomplicated viral infection clear more quickly. They may be prescribed if a healthcare professional diagnoses a separate bacterial infection or bacterial complication.

Antiviral medicines may sometimes be prescribed for influenza, particularly for people who are at greater risk of complications or in certain clinical circumstances. They are not routinely required for everyone who has flu.

When Do I Need to Seek Medical Advice?

Most people with a cold or flu will recover without needing to see a GP. However, you should seek medical advice if you are concerned about your symptoms or if you are at greater risk of becoming seriously ill.

For a cold, NHS advice includes contacting a GP if:

• You have a high temperature for more than three days
• Your symptoms are getting worse rather than improving
• You feel short of breath or have chest pain
• Your symptoms have not improved after around 10 days
• You have a cough lasting more than three weeks
• You have a long-term condition such as diabetes or a heart, lung or kidney condition
• You have a weakened immune system
• You are concerned about a child’s symptoms

People with flu who feel very unwell, are short of breath or have symptoms that are not improving should also seek medical advice. Call 999 or go to A&E for severe breathing difficulties, sudden chest pain or other symptoms requiring emergency care.

Are There Any Complications from a Cold or Flu?

Most colds get better without causing serious problems, although complications can occasionally occur. These may include infections affecting the ears, sinuses or chest.

Flu can cause more serious complications, particularly in older people, pregnant women, young children and people with certain long-term health conditions or weakened immune systems. Possible complications include pneumonia and worsening of existing health conditions.

Antibiotics are not prescribed simply to prevent these complications. They may be needed if a bacterial infection develops and a healthcare professional considers antibiotic treatment appropriate.

Understanding the Seasonal Pattern

Colds and flu are particularly common during the colder months. One reason is that people spend more time together indoors, giving respiratory viruses more opportunities to spread from person to person.

Environmental conditions can also influence the survival and transmission of respiratory viruses. However, being cold itself does not directly give you a cold or flu. You must be exposed to a virus to become infected.

This seasonal pattern makes autumn and winter a particularly useful time to pay attention to hand hygiene, respiratory etiquette and flu vaccination if you are eligible.

What Can I Do to Prevent Getting a Cold or Flu?

It is impossible to avoid every respiratory infection, but simple measures can reduce your risk of catching or spreading viruses.

• Wash your hands regularly with soap and warm water
• Avoid touching your eyes, nose and mouth with unwashed hands
• Cover coughs and sneezes with a tissue, then dispose of the tissue promptly
• Clean frequently touched surfaces regularly
• Avoid sharing towels, cups and similar household items with someone who has a cold
• Stay at home and avoid close contact with other people if you have a high temperature or feel too unwell for normal activities
• Have the annual flu vaccine if it is recommended for you

A balanced diet, regular physical activity and adequate sleep are all important parts of maintaining general health. No individual food or supplement can guarantee that you will avoid colds or flu.

Vitamin C is an important nutrient and can be obtained naturally from a varied diet containing fruit and vegetables. However, the NHS notes that there is little evidence that vitamin C supplements prevent colds or help people recover more quickly.

Cold or Flu: Knowing the Difference

Colds and flu have several symptoms in common, but flu typically begins more suddenly and causes more severe fatigue, aches and general illness. Most cases can be managed at home with rest, fluids and appropriate symptom relief.

Good hand hygiene and staying away from others while you are unwell can reduce the spread of respiratory infections. If you are eligible for an annual flu vaccination, having it provides an additional layer of protection against influenza and its complications.

If your symptoms are severe, are getting worse or are not improving as expected, contact your GP, NHS 111 or another appropriate healthcare professional for advice.

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