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What’s the difference between a cold, the flu, hay fever, pneumonia & covid?

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It’s normal to feel poorly with a cough, headache, and runny nose from time to time. But sometimes symptoms can be more serious and leave us in bed for days or even weeks at a time. In severe cases, symptoms that start out mild may end up needing medical care in a hospital.

With COVID-19 still circulating around the world, it’s important to understand when symptoms may be more than they seem. Read on for a guide to spotting the differences between the common cold, flu, coronavirus, pneumonia, and hay fever, and for some simple answers to some frequently asked questions on this topic.

Similarities and differences in symptoms

If you're unsure on what illness you might have then check your symptoms here. Our table below explains the differences between the symptoms of the common cold, flu, COVID-19, pneumonia and hay fever.

and symptoms
Common cold Flu  COVID-19 Pneumonia Hay fever
Onset of
Gradual Sudden Gradual or sudden Gradual or sudden Gradual or sudden
Fever Unlikely Common Common Common Unlikely
Chills Unlikely Sometimes Sometimes Common Unlikely
Body aches Unlikely Sometimes Sometimes Sometimes Unlikely
Sometimes Common Common Sometimes Sometimes
Sneezing Common Sometimes Unlikely Unlikely Common
Cough Sometimes Common Common Common Common (usually dry)
Sore throat Common Sometimes Sometimes Unlikely Sometimes (itchy throat)
Headache Sometimes Common Sometimes Sometimes Common
Runny or
stuffy nose
Common Sometimes Unlikely Unlikely Common

The common cold

The common cold is a respiratory illness, meaning it affects your airways. It’s caused by a group of similar viruses. There’s very little risk of becoming seriously ill from a cold, and most people recover fully within a couple of weeks. You’ll usually only be at risk if you’re already very unwell e.g. you have a weakened immune system.

Symptoms of the common cold include:

  • Sneezing
  • Runny or stuffy nose
  • Sore throat
  • Cough
  • Headache

The flu

Influenza or "flu" is an infection of the respiratory system caused by strains of the influenza virus. It’s especially common in winter and can cause illness for several days or weeks. Tiredness and feeling achy can make it difficult for you to carry on as normal.

Symptoms of the flu include:

  • High temperature
  • Headache
  • Aches and pains
  • Sore throat
  • Tiredness

After exposure to the flu, symptoms tend to come on very quickly and are more intense than the common cold. However, the flu is unlikely to cause a stay in hospital unless you’re in a high-risk category e.g. you’re pregnant or have a serious health condition.

If you're at risk, it’s best that you get your annual flu vaccine.

Flu vaccinations

The coronavirus (COVID-19)

COVID-19 is a respiratory illness caused by a new coronavirus first identified in Wuhan, China in 2019. The virus has never been in circulation before, meaning no-one had any natural immunity to it. Since the beginning of the pandemic the symptoms of COVID-19 and self-isolation guidance have changed, read on to find out more.

Symptoms of COVID-19 include:

  • a high temperature or shivering (chills)
  • a new, continuous cough – this means coughing a lot for more than an hour, or 3 or more coughing episodes in 24 hours
  • a loss or change to your sense of smell or taste
  • shortness of breath
  • Tiredness and exhaustion
  • Aches
  • Headache
  • Sore throat
  • Blocked or runny nose
  • Loss of appetite
  • Feeling nauseous or being sick
  • Diarrhoea

What to do if you’re having COVID-19 symptoms

If you have symptoms of COVID-19 you should try to stay home and avoid contact with other people for 5 days. You should also avoid meeting people who are higher risk of COVID-19 for 10 days even if they have had the vaccine.

This time period starts the day after you do a test, you can order lateral flow tests online.

If children or those under 18 tests positive they should stay home and avoid contact with others for 3 days. For more guidance about self-isolating, read this page on the NHS website.

What is a ‘twindemic’?

During the winter months the UK sees the number of people getting flu increase and at the same time infection rates of COVID-19 also rise. These combine to create a ‘twindemic’ meaning more people are in hospital with these viruses compared to other times of year.

    COVID-19 swab test banner


    Pneumonia is a very serious respiratory illness that causes inflammation of the lungs and leads to difficulty breathing. It is usually caused by a bacterial infection. It can also be caused by a viral infection, like coronavirus (COVID-19).

    The main difference between bacterial and viral pneumonia is that you can treat bacterial pneumonia with antibiotics. Viral pneumonia doesn’t tend to have a specific treatment other than the management of symptoms, although antiviral medicines are sometimes used.

    Symptoms of pneumonia include:

    • Dry cough
    • Phlegm producing cough that may be yellow or green mucus
    • Difficulty breathing
    • Fast heartbeat
    • Fever and chills
    • Feeling unwell
    • Loss of appetite
    • Chest pain that worsens when breathing or coughing

    Pneumonia can have serious health complications, so if you’re experiencing any of these symptoms it’s a good idea to speak to your GP or call 111.

    If you’re over 65, have asthma or smoke you are more at risk of get seriously ill from pneumonia and should consider getting the pneumonia vaccine. Find out more about who’s at risk and whether you can get the pneumonia vaccine in one of our stores on our service page.

    Read our pneumonia and pregnancy and pneumonia vaccine side effects blogs for more advice. Book your pneumonia jab

    Hay fever and allergies

    The symptoms of hay fever and other allergies can sometimes be mistaken for a viral infection. Hay fever symptoms are usually at their worst between late March and September, when it’s warm, humid, and windy. This is also when the pollen count is at its highest.

    Symptoms of allergies tend to develop more rapidly than the symptoms of a cold, which can take a couple of days. 

    Symptoms of hay fever include:

    • Sneezing
    • Coughing
    • Runny or blocked nose
    • Itchy, red, watery eyes
    • Itchy throat and nose
    • Loss of smell
    • Headache
    • Earache
    • Feeling tired

    If you have asthma, you might also experience shortness of breath, a tight feeling in your chest, and wheezing.

    If you think hay fever or other allergies such as mould allergies may be the cause of your symptoms, try taking some antihistamines

    Treatments for hay fever

    Depending on your hay fever symptoms you experience, you might want to look at different medications. For example, if you experience a runny nose you might want a nasal spray or if you get itchy eyes you could try eye drops or even a soothing eye mask. For more tips on hay fever, here’s our advice on how to minimise hay fever symptoms.

    Frequently asked questions about the common cold, the flu, COVID-19, and pneumonia

    • Is coronavirus more severe than the flu?

      COVID-19 can be more serious than seasonal influenza in some people. That’s why it’s important to follow government advice and take appropriate precautions to keep you and those around you safe and well.

      Both COVID-19 and the flu can result in severe complications, such as:

      • Respiratory failure – a condition where not enough oxygen passes from your lungs into your blood
      • Pneumonia – an infection in one or both lungs that causes inflammation and fluid to build up, causing difficulty in breathing
      • Sepsis – when the immune system goes into overdrive in reaction to an infection, and begins to damage the body’s own tissues and organs
      • Multiple organ failure – where two or more organ systems begin to shut down
      • Worsening of pre-existing conditions – for example asthma or heart disease
      • Secondary bacterial infections – a second infection that occurs as a result of the damage caused by the initial influenza or COVID-19 infection

      COVID-19 is associated with some additional complications, including:

      • Blood clots – clots in the veins or arteries of the heart, lungs, legs or brain have presented themselves in more severely ill patients, leading to strokes or amputations
      • Paediatric inflammatory multisystem syndrome (PIMS) associated with COVID-19 – a new condition that happens weeks after someone has had COVID-19. Mostly young people and adolescents are affected, but some children get PIMS too. PIMS causes swelling in the body and parts of the body become inflamed. Symptoms can include tiredness, a rash, swollen hands and feet. Read the GOSH guide to find out more. 

      The good news is that there are now vaccines available for COVID-19. To have the best protection against COVID-19, it’s important to get the vaccine when you are offered it. It’s also a good idea to get your annual flu jab.

    • Who is more at risk from coronavirus?

      On top of being in a high risk category, Public Health England have identified the following factors that may place you more at risk of catching COVID-19:

      • Being a man (men appear more susceptible to COVID-19)
      • Where in the country you live, as the risk is higher in poorer more crowded areas
      • Being from a Black, Asian or Minority Ethnic (BAME) background
      • Living in a care home
      • Having certain high-exposure jobs such as nurse or bus driver
    • How is the transmission of COVID-19 in children different from flu?

      According to studies, it appears that children are less affected by the COVID-19 virus than adults. This is in contrast to the flu, where children are equally affected and significantly drive influenza transmission rates within a community. 

      However, you should still take steps to keep your children protected. This includes keeping an eye out for symptoms, which generally seem to be the same as those seen in adults.

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    • How to stay safe

      There are a few different ways to keep yourself protected from viruses:

      • Get vaccinated for the flu, COVID-19, and pneumonia. The COVID-19 vaccine is free for everybody, and the flu vaccine and pneumonia vaccine are free for people who are high-risk. If you aren’t eligible for free vaccines, you can order your flu vaccine or pneumonia vaccine from LloydsPharmacy and receive your injections in your local store after a consulatation.
      • Frequently wash your hands with soap and warm water – you should try to wash them for at least 20 seconds to make sure they’re properly clean. If soap and water isn’t available, use a hand sanitising gel, and wash your hands with soap and water at the next available opportunity.
      • Avoid touching your nose, eyes and mouth when out and about, as viruses can linger on surfaces and enter the body in this way.
      • Taking a lateral flow test regularly helps to keep friends and family safe. You can order lateral flow tests kits online or you can collect them from your local pharmacy.
      • Keep healthy – ensure you maintain a healthy diet and proper exercise.
      • Use face coverings, such as face masks - this limits the spread of virus-spreading droplets in the air.

    Is it a cold, the flu, hay fever, pneumonia or COVID-19?

    When you’re feeling under the weather it’s helpful to know what illness your symptoms could be. We have COVID tests you can take so you can find out if you need to follow guidelines. It’s always a good idea to look after yourself by getting plenty of rest if you can, staying hydrated and taking cough and cold medicines is appropriate. You can also help to protect yourself from viruses by having the flu vaccine and the pneumonia vaccination.

    For more advice about common illnesses read our glandular fever and tonsillitis guides. We also have helpful blogs about staying safe with the typhoid vaccine and monkeypox guidance.