woman wearing a coat and scarf, using a tissue to wipe her nose

Colds and flu: what you need to know

Most of us come down with cold or flu viruses at some point during the year. Find out everything you need to know about managing the winter lurgy

Written by Charlotte Haigh on January 22, 2019 Reviewed by Dr Gio Miletto on January 30, 2019

You have the tell-tale symptoms: sore throat, cough, runny nose. But what exactly is happening in your body when you’re hit with a cold or flu virus? And how should you treat it?

What are colds and flu?

Colds and flu are both upper respiratory infections affecting your nose, throat and lungs – they’re just caused by different viruses.1 There are over 200 types of viruses that can cause common cold symptoms with around 50% being rhinoviruses,2 while the flu is caused by the influenza virus.3 Colds are the most common respiratory virus: children can get eight or more a year,4 and by the time you’re an adult, you still get two to three.5

How can you tell the difference between a cold and flu?

We all know people who say they’ve got the flu when it’s probably just a cold – but sometimes it can be hard to tell what you’ve got.

As a rough guide, cold symptoms:6
  • come on gradually
  • affect just your nose and throat
  • you can still go to work and school, though you’ll still feel unwell
Flu symptoms:7
  • more severe
  • come on more suddenly, within a few hours
  • affect more than just your nose and throat, for example giving you a fever, aching muscles, headache and chills
  • more likely to make you feel so unwell and exhausted that you can’t get on with daily life

How do you catch a cold or flu?

Either through the air – the viruses travel in droplets when an infected person coughs, sneezes or speaks – or from picking them up from a hard surface, such as a door handle, and transferring them to your nose, mouth or eyes.8 Cold symptoms develop 1-3 days after exposure;6 for flu symptoms, it’s 1-4 days.9

What are the symptoms?

Those tell-tale symptoms aren’t caused by the virus – but by your own immune system’s defence mechanisms. For example, white blood cells called T-cell lymphocyte attack the flu virus in your lungs, causing a build-up of mucus and difficulty breathing.10 For colds, symptoms include:11
  • blocked or runny nose
  • sore throat
  • coughing
  • headaches
  • sneezing
  • loss of your senses of smell and taste
  • muscle aches
And flu symptoms include:12
  • sudden fever, with a temperature of 38°C or higher
  • fatigue
  • headache
  • muscle aches
  • sore throat
  • loss of appetite
  • trouble sleeping
  • dry cough

Who gets the most colds and flu?

For colds, definitely children – they can get more than eight colds a year.13 Adults have 2-3 a year.14 When it comes to flu, over-65s and children are most likely to contract an infection.15 Certain factors increase your risk of picking up a bug:16,17
  • being in a big group of people – for example, at school or a concert
  • smoking
  • a weakened immune system
  • the season – you’re more likely to catch a cold in autumn and winter

Can you prevent colds and flu?

Both cold and flu viruses can be infectious one day before someone shows symptoms – so avoiding people who are obviously coughing and spluttering isn’t enough.18

Try these tips:

  • wash your hands regularly with soap and warm water
  • avoid touching your face too much – that way you don’t transfer bugs to your nose or eyes
  • don’t share items such as towels, cups and cutlery
  • stay fit and healthy, with plenty of sleep and a balanced diet – this will help you fight off any viruses you come into contact with19
  • try echinacea – a 2014 Cochrane review found that the herb could help support your body in preventing colds20

  • take vitamin D – it reduces your risk of catching cold or flu, according to a 2017 study published in The BMJ21
  • get the NHS flu vaccine

Treating colds and flu

If you’re ill with a cold or flu, get plenty of rest, drink lots of fluids, stay warm and eat a healthy diet.22, 23

You could also take the mineral zinc – a 2012 review of 17 studies involving more than 2000 people by Canada’s McMaster University reported it could help shorten a cold by interfering with the way the virus replicates.24

At the moment, there’s no way to cure a cold or the flu – but scientists are working on it.

For example, there’s some exciting research into substances called antimicrobial peptides, which are part of our immune response and could, one day, be harnessed to help fight the viruses, according to a 2018 study by Edinburgh Napier University.25

When to speak to your GP

For most people, there’s no need to see a doctor, even if you have flu – it’s just a question of letting the illness take its course.

The NHS advises you speak to your GP if your cold symptoms:26
  • suddenly get worse
  • don’t clear after three weeks
  • you have a very high temperature
  • you find it hard to breathe
  • you’re worried about your child’s condition
  • you have a long-term medical condition
With flu, call 111 if:27
  • your symptoms don’t ease after a week
  • you have a long-term medical condition
  • are pregnant
  • are over 65
  • you’re worried about your child’s condition
And always call 999 or go to A&E immediately if you start coughing up blood, have trouble breathing or develop sudden chest pain.28 Shop Cold & Immune Support Advice is for information only and should not replace medical care. Please check with your GP before trying any remedies.


1. Centers for Disease Control and Prevention. Cold Versus Flu 2. Medical News Today. All about the common cold 3. Centers for Disease Control and Prevention. Influenza (Flu) Viruses 4. NHS. Colds, coughs and ear infections in children 5. Centers for Disease Control and Prevention. Common Colds: Protect Yourself and Others 6. NHS. Common Cold

7. As above

8. Mayo Clinic. Influenza 9. Mayo Clinic. Common Cold 10. Centers for Disease Control and Prevention. Clinical signs and symptoms of influenza 11. Laura Haynes. The Conversation. What the flu does to your body, and why it makes you feel so awful

12. As Source 6

13. NHS. Flu 14. NHS. Coughs, colds and ear infections in children 15. Allan GM, Arroll B. Prevention and treatment of the common cold: making sense of the evidence

16. As Source 8
17. As Source 8
18. As Source 9

19. MedicineNet. How long is a cold or flu contagious

20. As Source 6

21. Cochrane. Echinacea for preventing and treating the common cold 22. Martineau A, et al. Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data

23. As Source 7
24. As Source 13

25. Science M, et al. Zinc for the treatment of the common cold: a systematic review and meta-analysis of randomized controlled trials 26. Casanova V, et al. Antiviral therapeutic approaches for human rhinovirus infections

27. As Source 6
28. As Source 13

29. As Source 13