- Colds can be just a sniffle, cough and sore throat, but flu affects the whole body
- Covid can cause serious breathing difficulties and a loss of taste and smell
Many of will be plagued with runny noses, coughs and sore throats this winter. But it can be tricky to tell whether a cold, flu or Covid is responsible.
While symptoms may vary between people, the common cold is usually mild and more of a ‘nuisance’, while the flu or Covid can keep you in bed for days, experts say.
Health chiefs this week warned that a wave of winter respiratory viruses is set to hit imminently, with cases of the vomiting bug norovirus already rocketing.
So, to help you tell the difference between the viruses, MailOnline has asked doctors and scientists to breakdown the most common symptoms of each.
Graphic shows the common symptoms (green tick), occasional and possible symptoms (orange circle) and the symptoms that never occur (red cross) with the common cold, flu and Covid
A common cold can hit you at any time of year, but it’s most likely creep up on you in the winter months, as with all respiratory illnesses.
‘Cold symptoms are more of a head cold with runny nose, sneezing, sore throat and blocked nose’, says Cardiff University’s Emeritus Professor Ron Eccles, who has spent decades researching the pesky bugs that cause them.
That means if your symptoms are mostly restricted to your upper airways it’s likely to be a cold, he says.
Rhinoviruses are the most common cause of a cold, but a minor infection of the nose and throat can be caused by one of more than 200 different viruses.
Cold weather alone can’t actually cause a cold. But the body is more susceptible to infection when the immune system is weaker — which can be caused by a drop in temperature, Professor Eccles says.
‘Colds usually develop gradually and can cause cough, congestion and fatigue’, says London-based NHS GP Dr Hana Patel.
‘They creep up on you with stuff like a runny nose or a sore throat.’
Colds can be told apart from the flu, as they tend to be ‘a nuisance’, while the flu ‘can knock you off your feet and keep you in bed’, Dr Patel says.
However, the overlap in symptoms between a cold and the flu, including sneezing and a blocked nose can make clinical diagnoses challenging, explains Dr Samuel White, based at the Medical Technologies Innovation Facility at Nottingham Trent University, who has spent years researching the immune system.
There are plenty of crossovers in symptoms between a cold and the flu, which is also more rife in the depths of winter.
Caused by influenza viruses, the illness usually causes people to have a cough, which is the most common crossover symptom.
But experts say that, although many symptoms are similar, the flu is typically much more intense and effects the whole body.
‘Flu symptoms typically have body symptoms such as chilliness, fever, headache and muscle aches and pains,’ according to Professor Eccles.
‘The flu feels worse because the symptoms affect the whole body and are not restricted to a head cold.’
Flu does tend to cause ‘more severe manifestations’, according to Professor Philippe Wilson, of One Health, Medical Technologies Innovation Facility, Nottingham Trent University, who has worked on numerous clinical trials and studied a range of diseases in both humans and animals.
In fact, one of the main differences is flu can cause stomach problems.
Explaining this, Professor Eccles says: ‘These can include a higher fever, profound body aches, and pronounced fatigue. Moreover, gastrointestinal symptoms like vomiting and diarrhoea are more prevalent in influenza cases.’
The flu also has the potential to be life-threatening. But this is usually only the case for those aged over 65, are pregnant, or who have long-term health conditions. A cold can only has the same effect in extremely rare cases.
This group is recommended to get an annual flu vaccine to help protect them against getting seriously ill.
Professor Wilson said: ‘Individuals generally experience more pronounced discomfort with the flu.
‘The heightened severity of symptoms, coupled with the potential for complications like pneumonia, underscores the significance of distinguishing between the two for appropriate management.’
A runny nose, sore throat, headache, persistent cough and fatigue are all commonly reported signs of Covid
At the start of the Covid pandemic, a loss of taste or smell, a continuous cough and a fever, were the three tell-tale signs of the virus.
But as new variants evolved and both vaccines and repeated waves of infection blunted the virus’s threat, the official symptom list continued to grow.
Now, a runny nose, sore throat, headache, persistent cough and fatigue are all reported signs of the virus.
The virus is still circulating in the UK, but isn’t sickening Brits at the same rate as it did in previous winters.
Although many Covid symptoms, such as coughing and nasal congestion, are shared with the flu and cold, Professor Wilson explains that the virus can have a more ‘persistent and pronounced impact on the respiratory system’.
He added: ‘Fever is a common sign, and in Covid, it tends to be more prolonged and elevated compared to typical colds.’
Another symptoms less common in cold and flu but spotted in the Covid-infected is shortness of breath, which Professor Wilson says can range from mild to severe.
A more unique and distinctive symptom of Covid is a sudden loss of taste and smell, which is far less common in common cold and flu.
Professor Wilson said: ‘Beyond these primary symptoms, severe cases of Covid can lead to complications such as chest pain, confusion, and bluish discoloration of the lips or face, indicating a need for immediate medical attention.’
However, Dr White stresses that getting vaccinations are ‘essential for preventing infection from common diseases like the flu’.
He added: ‘While there are shared symptoms, Covid distinguishes itself through its potential for severe outcomes and unique manifestations like loss of taste and smell.
‘Prioritising vaccinations and adhering to preventive measures remains paramount in mitigating the impact of these respiratory illnesses.’