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How to distinguish flu from COVID and cold: doctor's advice

How to distinguish flu from COVID and cold: doctor's advice How to distinguish viruses, colds, flu and coronavirus (photo:

Winter is nearly here, bringing along its share of seasonal illnesses. Runny noses, coughs, and nasal congestion are widespread. Are you dealing with a common cold, or could it be something more serious caught from a crowd of similarly symptomatic individuals? Learn how to differentiate between the flu, coronavirus, a cold, or a virus in this guidance from WebMD.

Take the test

It's important to note that standard symptoms are similar across different disease variants. Getting vaccinated against the flu or coronavirus doesn't guarantee immunity, but it provides protection against severe consequences. However, there are clues to help gauge the seriousness of your illness.

Experts suggest having at-home express tests for coronavirus. By the 2nd or 3rd day of illness, these tests can indicate whether you have COVID.

“Being vaccinated does keep [these viruses] from striking the chest,” said Panagis Galiatsatos, MD, a pulmonary and critical care doctor at Johns Hopkins. “Vaccinated patients may get a mild cough, but a lot of their symptoms stay more as an upper respiratory issue, like nasal congestion – like a bad cold.”

Loss of taste and smell, once a characteristic symptom of coronavirus, is now less prevalent. Similar symptoms can also occur with a severe cold or flu.

The landscape has shifted, with many individuals having antibodies that offer protection against the severe effects of the virus, whether from previous infection, vaccination, or a combination of both.

It's crucial to be aware that COVID can manifest with gastrointestinal symptoms such as nausea, vomiting, and diarrhea. If you experience these symptoms during a cold, it's advisable to take a coronavirus test.

Pay attention to the time of onset of symptoms

Symptoms of a cold appear very quickly - if you are cold during the day, then in the evening you will start to feel bad. With the flu, the situation is completely different - one of the most characteristic features of this disease is that the onset of the disease is usually sudden with a sharp rise in temperature and severe manifestations of symptoms.

“You might be minding your own business, feeling OK, and then all of the sudden you get in your car and you feel like you’ve been hit by a dump truck," explains Peter Chin-Hong, MD, an infectious disease expert at the University of California, San Francisco.

With COVID, there are also unique symptomatic features - symptoms can be absent at all or be very mild. They are similar to a cold, but over the course of a week, you will gradually get worse, not better.

“COVID has this biphasic pattern, whereas colds and RSV don’t – it’s when you are kind of doing OK, and then you fall off a cliff,” said Chin-Hong. “That’s why early treatment with Paxlovid or remdesivir is so important because it can prevent that second phase from happening.”

How to distinguish all diseases


  • The disease lasts from 3 to 7 days and at the end of the period there is complete recovery
  • The onset of the disease is gradual. The temperature rises, but not above 38
  • Runny nose and sore throat - moderate or minor
  • There is a cough, but it passes quickly
  • No digestive problems
  • Lymph nodes are not enlarged


  • Sudden onset within a few hours
  • High temperature (39-40 degrees) lasting several days
  • Body aches and muscle pain
  • Intense headache
  • Infrequent nose congestion
  • Red and potentially sore throat
  • Strong cough developing into bronchitis
  • Unenlarged lymph nodes
  • Possible vomiting and diarrhea
  • Relief within 7-10 days, full recovery in 15-21 days

SARS (Virus)

  • Gradual onset with symptoms in the first two or three days
  • Temperature of about 38 degrees, decreasing after 2-3 days
  • Aching in the bones, body weakness (less intense than flu)
  • Blocked nose, lacrimation, runny nose
  • Red throat, and cough appear initially and gradually fades
  • Possible increase in lymph nodes
  • Rare gastrointestinal issues
  • Duration of 7-10 days, with weakness and lingering symptoms possible by the 14th day


  • Gradual onset of symptoms
  • Possible increase in temperature, chills, and fever
  • Severe fatigue
  • Cough and shortness of breath
  • Sore throat
  • Blocked nose and potential runny nose
  • Muscle pain
  • Headache
  • Vomiting and diarrhea
  • Loss of taste and smell

This material is for informational purposes only and should not be used for medical diagnosis or self-treatment. Our goal is to provide readers with accurate information about symptoms, causes, and methods of detecting diseases. RBС-Ukraine is not responsible for any diagnoses that readers may make based on materials from the resource. We do not recommend self-treatment and advise consulting a doctor in case of any health concerns.