Flu vs COVID Symptoms: How to Tell Them Apart From a Common Cold

Flu vs COVID symptoms overlap a lot: both can cause a high temperature, a cough, a sore throat, body aches and tiredness, and the NHS says COVID-19 symptoms are very similar to those of colds and flu. The biggest clue is speed. Flu tends to come on quickly, within a few hours, while a cold builds up gradually over 2 to 3 days, and only a test can tell for certain which virus you have.

This guide compares the three side by side, explains how long each usually lasts, and shows when home care is enough and when to see a doctor.

Cold, flu or COVID-19: the quick comparison

The table below brings together what the NHS and the World Health Organization (WHO) list for each illness. "Not listed" means the source used for that illness does not mention the symptom, not that it can never happen.

Two things stand out. First, a loss of taste or smell can happen with a cold as well as COVID-19, so on its own it does not prove you have COVID-19. Second, the NHS common cold page says a cold makes you feel unwell but usually still able to carry on as normal, for example going to work, while flu makes you feel exhausted and too unwell to carry on.

How quickly symptoms start and how long they last

According to the WHO, flu symptoms usually begin around 2 days after someone is infected, although this can range from 1 to 4 days. Most people recover from the fever and other symptoms within a week without needing medical care, but the cough can be severe and can last 2 weeks or more.

A cold comes on gradually over 2 to 3 days, and you should begin to feel better in about 1 to 2 weeks. Symptoms can last longer in young children, who may also be irritable, have trouble feeding and sleeping, breathe through their mouth and be sick after coughing.

For COVID-19, the NHS says most people feel better within a few weeks, but it can take longer to recover. For some people it can be a more serious illness and their symptoms can last longer.

How long to keep away from others

• Cold: you are infectious from a few days before symptoms start until all your symptoms have gone, which usually takes 1 to 2 weeks.
• Flu: WHO advises people with mild symptoms to stay home to avoid infecting other people.
• COVID-19: try to stay at home and avoid contact with others if you have a high temperature or do not feel well enough for work, school or your normal activities. If you choose to test and the result is positive, the NHS advice is to try to stay home for 3 days if you are under 18, or 5 days if you are 18 or over, and to avoid people who are more likely to get seriously ill, such as those with a weakened immune system, for 10 days.

If your child has mild COVID-19 symptoms such as a runny nose, sore throat or mild cough and feels well enough, the NHS says they can go to school.

Symptoms of each illness in more detail

Common cold

The main symptoms of a cold are a blocked or runny nose, sneezing, a sore throat, a hoarse voice, a cough and feeling tired and unwell. Some people also get a high temperature, aching muscles, a loss of taste and smell, or a feeling of pressure in the ears and face. Colds are caused by viruses and spread through germs from coughs and sneezes, which can live on hands and surfaces for 24 hours.

Flu

WHO lists the symptoms of seasonal flu as:

• a sudden fever
• a cough, usually dry
• headache
• muscle and joint pain
• feeling very unwell (severe malaise)
• sore throat
• runny nose

Flu spreads easily, especially in crowded places such as schools and nursing homes. When an infected person coughs or sneezes, droplets carrying the virus spread into the air and can infect people close by, and the virus can also spread on hands. In severe cases, flu can lead to pneumonia and sepsis. You can read more about pneumonia in our guide on whether bronchitis, pneumonia and strep throat are contagious.

COVID-19

The NHS lists COVID-19 symptoms as a high temperature, a new and continuous cough (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, feeling tired or exhausted, an aching body, a headache, a sore throat, a blocked or runny nose, loss of appetite, diarrhoea, and feeling sick or being sick.

Because these illnesses look so alike, WHO notes that other viruses, including the one that causes COVID-19, can cause a flu-like illness, and a laboratory test is needed to be sure which one it is.

Looking after yourself at home

Most people with a cold, mild flu or mild COVID-19 can recover at home. The NHS and WHO advise:

• getting plenty of rest
• drinking plenty of fluids such as water to avoid dehydration (your pee should be light yellow or clear), which is especially important in Pakistan's hot weather
• trying a teaspoon of honey for a cough, or a hot lemon and honey drink for a sore throat (do not give honey to babies under 12 months)
• gargling salt water for a sore throat (not suitable for children)
• breathing in steam to ease a blocked nose, such as sitting in the bathroom with a hot shower running (do not let children breathe in steam from a bowl of hot water because of the risk of scalding)
• not smoking, as it can make cold symptoms worse

If COVID-19 makes you breathless, the NHS suggests sitting upright, relaxing your shoulders, leaning forward slightly with your hands on your knees, and breathing slowly in through your nose and out through your mouth. Lie on your side or sit up rather than lying on your back if you have a cough. The NHS also advises not using a fan to cool the room, as it may spread the virus, which is worth remembering in summer.

A pharmacist can advise on cold and cough medicines, including which are not suitable for babies, children or pregnant women. Antibiotics do not help colds, because colds are caused by viruses. For flu, WHO says people at high risk or with severe symptoms should be treated with antiviral medicines as soon as possible, and a doctor will decide whether these are right for you.

Who is at higher risk

Anyone can get flu, but WHO says some people are at greater risk of severe illness or complications:

• pregnant women
• children under 5 years of age
• older people
• people with long-term conditions of the heart, lungs, kidneys, liver or blood, or metabolic or neurodevelopmental conditions
• people with a weakened immune system, for example from HIV, chemotherapy, steroids or cancer

For COVID-19, the NHS says it is particularly important to get help if you are pregnant, aged 60 or over, or have a weakened immune system. For a cold, see a GP if you have a long-term condition such as diabetes, or a heart, lung or kidney condition.

Flu vaccination: what WHO recommends

WHO says vaccination is the best way to prevent flu, and safe and effective vaccines have been used for more than 60 years. Protection from the vaccine fades over time, so a yearly vaccine is recommended. In older people the vaccine may be less effective, but it still makes the illness less severe and reduces the chance of complications and death.

WHO recommends a yearly flu vaccine for:

• pregnant women
• children aged 6 months to 5 years
• people over 65
• people with long-term medical conditions
• health workers

Note that the flu vaccine does not prevent colds. Other ways to lower the risk of flu include washing and drying your hands regularly, covering your mouth and nose when you cough or sneeze, throwing away tissues properly, staying home when you feel unwell, avoiding close contact with sick people and not touching your eyes, nose or mouth. Ask your doctor whether the flu vaccine is suitable for you or your family.

When to see a doctor

See a doctor if:

• you have a high temperature for more than 3 days with a cold, or for 5 days or more with COVID-19
• your temperature is very high, or does not come down with fever medicine
• you feel hot, cold or shivery, or your symptoms are getting worse
• you feel short of breath or have chest pain
• your cold symptoms do not get better after 10 days
• you have had a cough for more than 3 weeks
• you have other signs of illness, such as a rash, loss of appetite or feeling weak
• a baby under 3 months has a temperature of 38C or higher, or a baby aged 3 to 6 months has a temperature of 39C or higher
• you are worried about your child's symptoms

Emergency: call 1122 or go to the emergency department if you or a child

• seems very unwell, is getting worse, or you think something is seriously wrong (children and babies can get unwell very quickly)
• has sudden chest pain
• is so breathless they cannot say short sentences when resting, or their breathing suddenly gets worse (in babies, the stomach may suck in under the ribs)
• starts coughing up blood
• collapses, faints, or has a seizure or fit for the first time
• has a rash that does not fade when you roll a glass over it

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Sources

• WHO — Influenza (seasonal)
• NHS — COVID-19 symptoms and what to do
• NHS — Common cold

Medical note: This guide is for general information and is not a substitute for advice from a doctor who can examine you.