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Can you tell the difference in symptoms between the flu and COVID-19?

With the flu season coming up at the end of the year, you'll want to figure out which is making you feel terrible.

Can you tell the difference in symptoms between the flu and COVID-19?

(Art: The New York Times/Luci Gutierrez)

As influenza season approaches, some people, especially parents, are worried that if they or their children should become ill, it may not be easy to know which disease they have: The flu or COVID-19.

They are correct. Most symptoms of the two diseases are so similar that short of a test – or two or three tests – it won’t be possible to know for sure. But there are some clues. (And it is possible to have both infections at the same time; some patients in China this year were found to have both.)


There are at least 100 viruses that can cause the common cold, but only four that cause seasonal flu. Many people who catch colds assume they have the flu, but experts consistently say the same thing about how to tell the difference: “Flu makes you feel as if you were hit by a truck”. The fever, aches and headaches of a bad case of influenza are generally worse than a case of respiratory syncytial virus, rhinovirus or other common cold viruses.

Everyone knows the symptoms of the flu: Fever, headaches, body aches, sore throat, runny nose, stuffed sinuses, coughing and sneezing – and, for infants, ear infections. Some victims, especially children, get diarrhoea or vomiting, too.

In severe cases, the most common complication is pneumonia. The typical signs of a flu pneumonia are shortness of breath, especially when you exert yourself, and unusually rapid breathing – doctors typically look for that in children – and sometimes, pain in the chest or back.


Knowing whether you have COVID-19 is much more complicated because there are so many different – and sometimes, pretty wacky – symptoms, many of which echo those of the flu.

The most common symptoms are high fever, sometimes with chills, a dry cough and fatigue.

The one sign that really distinguishes the two infections is that many COVID-19 victims suddenly lose their sense of smell – not because they have a stuffy nose but because they don’t register even strong odours like onions or coffee. Not all virus victims get anosmia, the formal name for loss of smell, but one study found that 87 per cent did.

READ: Nothing to sniff at: Why you might lose your sense of smell as you get older

Less common symptoms include a sore throat, congestion, runny nose, vomiting, diarrhoea, stomach pain and feeling somewhat out of breath when exerting yourself. Some victims have red or itchy eyes, and some get redness or blisters on their fingers or toes – so-called COVID toes, which resemble chilblains.

More dangerous symptoms, which mean you should get immediate medical attention, include serious breathing difficulty; pain or pressure in the chest; blue lips or blue face; confusion or incoherent answers to simple questions; and collapsing or losing consciousness.

Adding to the disease’s fearsome nature is that it can cause blood clots that lead to heart damage, brain damage and lung damage. And even some cases that appear mild or asymptomatic create signs of what doctors believe may be long-lasting heart damage.

Another unusual aspect of COVID is that people sometimes develop pneumonia without realising how sick they are. Doctors are unsure why; one theory is that the air sacs in the lungs are damaged in a way that does not cause the build-up of carbon dioxide, which creates that “desperate for air” feeling.

Many doctors recommend buying a pulse oximeter, a fingertip device that measures oxygen levels in the blood. Multiple readings below 92 per cent should trigger a call to a doctor. The earlier pneumonia is caught, the better the outcome.


Children generally get through COVID-19 with few problems; for the youngest ages, it is thought to be less dangerous than the flu.

Children have the same constellation of symptoms that adults do, although parents may be more likely to notice it when their youngsters have runny noses, red eyes and the exhausted crankiness that comes from just feeling terrible.

Dangerous symptoms include difficulty breathing, bluish lips, confusion or inability to wake up, and intense abdominal pains or inability to keep down any liquids. If there are any signs of these, it is important to get the child to a doctor or hospital quickly.

In very rare cases, children can get multi-system inflammatory syndrome, which is thought to be caused by an overactive immune response, and can cause shock and organ failure.

But doctors emphasise that it is rare and that parents should realise it is highly unlikely their sick child has it.

By Donald McNeil Jr © The New York Times

This article originally appeared in The New York Times.