Common Cold or Flu or Coronavirus: How to differentiate between these common winter illnesses?

This blog will focus on the three most common winter illnesses that are seen in an adult……

COMMON COLD, FLU, and COVID-19 (CORONAVIRUS induced illness 2019).

Many of you think that all are the almost same…..but by the end of this blog, you will be more aware and open-eyed.

Why should winters be blamed for these illnesses?

There are a number of reasons why cough/cold/flu are more prevalent in the winter:

People are indoors more; breathing in the recirculated air of tightly sealed buildings facilitates the spread of viruses from person to person.

The lower humidity of centrally-heated buildings is a good environment for fostering viruses, which seem to survive longer in drier conditions.

School and work environments bring a lot of people in close contact with one another, creating opportunities for viruses to spread.

In winters, the days are short and there is less sunlight also. Sunlight is a source of Vitamin D for the body. And vitamin-D in turn helps in boosting the immune system. Hence, in winters, due to low vitamin D in the body, immunity might be low, making one more vulnerable to infection.

During winters, the air is very cold. So, when this cold air is breathed in, the blood vessels of the nose constrict and avoid losing heat. Constriction of blood vessels of the nose means that the White blood cells (the good cells of the body that attack any virus/bacteria) can’t reach the mucus membranes of the nose and hence cannot kill any viruses that we inhale.

Colds are mainly spread from person to person through inhaling droplets of secretions from infected people. When an ill person coughs or sneezes, he or she is likely to transmit thousands of virus-laden droplets. Cold viruses can survive for up to 2 hours on a given surface. When a surface is contaminated by a cough or sneeze, you may catch a cold just by touching the surface and then touching your eyes, mouth, or nose. Within 2 to 3 days of infection, symptoms begin.

And, Voila!!!!!! You have caught a cold


The average attacks of COMMON COLD in a year in an adult can be 2-4.  The most common viruses causing the common cold are:

1. Rhinovirus (most common in adults),

2. Parainfluenza viruses,

3. Adenovirus,

4. Picornavirus

5. Respiratory syncytial virus (RSV)

6. Influenza virus (FLU)

Respiratory syncytial virus (RSV) and influenza virus are more destructive to respiratory cilia.

The infection is usually contracted through airborne droplets. The incubation period is 1–4 days and the illness lasts for 2–3 weeks.


Usually, the common cold begins with–

  • A sore throat OR may be a burning sensation at the back of nose, which lasts for 1 or 2 days and then followed by
  • Cough,
  • Nasal discharge,
  • Nasal stuffiness,
  • Sneezing,
  • Sometimes Mild fever

Treatment of Common Cold-

1. ANTIBIOTICS have NO role in the treatment of the common cold.

2. Bed Rest

3. Plenty of fluids

4. Steam inhalation (should be taken in moderation).

5. Saline irrigation of the nose can help in some cases

6. Vitamin C can be used.

7. Antihistamines like Levocetrizine, Fexofenadine, Loratidine, Diphenhydramine, Chlorpheniramine, Cetrizine etc. They help in controlling nasal discharge.

CAUTION with Antihistamines:

  • Antihistamines may impair psychomotor performance.
  • Patients should not drive or operate heavy machinery.
  • In elderly patients (> 65–70 years of age) they are avoided as the risks of delirium and cognitive decline are high.

8. Oral decongestants like Ephedrine, Pseudoephedrine, Phenylephrine.
Nasal decongestants that come in form of nasal drops/sprays e.g. Otrivin, Nasivion, etc. They help in relieving blocked nose/stuffy nose, and pressure due to sinusitis.

CAUTION with Decongestants:

  • Otrivin, Nasivion type of nasal drops SHOULD NOT BE used for more than 3-5 days, because these are habit-forming drugs, and patients will get addicted to using these drops.
  • They may cause insomnia and agitation.
  • Should be used with caution in cases of hypertension, ischemic heart disease, glaucoma, prostatic hypertrophy, diabetes mellitus and geriatric patients.
  • They should NOT be used in patients using monoamine oxidase (MAO) inhibitors or having uncontrolled hypertension or severe coronary artery disease.

9. Cough Suppressants like Dextromethorphan, Codeine, Levocloperastine, etc.
To relieve the patient from bouts of dry cough.

10. Sputum expelling or Expectorants like N-acetylcysteine, Bromhexine, Guaifenesin, etc.
These thin out and loosen the sticky thick mucus in the throat or chest, which gets easily expelled out when the patient coughs.


Are COMMON COLD and FLU one and the same thing?


The symptoms of common cold and flu are the same, hence it’s difficult to tell. Both are widespread during winter months and both affect the upper respiratory tract system (nose, throat, and trachea). But, the following mentions the key differences between the two—

Causative Organism of FLU – Influenza virus

Transmission –

1. The transmission is from person to person by droplet infection through coughing or sneezing by infected persons, and

2. Fomites means people may become infected by touching a surface or object— with flu viruses on it and then touching their mouth, nose, or eyes.

Incubation period-

1–7 days.


From 1 day before to 7 days after the onset of symptoms, the patient may spread the infection to everyone who comes in contact with him/her.

If flu persists for more than 7 days, chances of communicability may persist till the resolution of illness.

Complications related to Flu-

Clinicians should expect complications such as-

  • Sinusitis,
  • Otitis media,
  • Croup,
  • Pneumonia,
  • Bronchiolitis,
  • Status asthamaticus,
  • Myocarditis,
  • Pericarditis,
  • Myositis,
  • Rhabdomyolysis,
  • Encephalitis,
  • Seizures,
  • Toxic shock syndrome and
  • Secondary bacterial pneumonia with or without sepsis.

Individuals at extremes of age and with pre-existing medical conditions are at higher risk of developing the above-mentioned complications.

How to diagnose a FLU?

Confirmation of FLU is done through:

  1. Real time (RT) PCR, or
  2. Isolation of the virus in culture, or
  3. Four-fold rise in virus specific neutralizing antibodies

Specimens such as –Nasopharyngeal swab, throat swab, or a nasal swab is obtained and sent for an RTPCR test or virus culture.

Treatment of FLU-

  1. Isolate or quarantine the patient
  2. Depending on the virus Antivirals like Oseltamivir, Zanamivir, Peramivir, Remdesivir, Molnupiravir etc. can be started.
  3. Supportive therapy like-
    Intravenous fluids,
    Maintaining nutrition.
  4. Oxygen therapy
  5. Ventilatory support
  6. Antibiotics to prevent bacterial infection of lungs
  7. Medications like vasopressors if patient goes in shock.
  8. Monitoring of vitals of patient like Temperature, BP, Pulse rate, Respiration rate, Oxygen saturation etc.

COVID-19 disease

FLU and COVID 19 have almost similar symptoms, but COVID-19 is commonly marked by a spectrum of the following symptoms-

  • Fever,
  • Cough,
  • Shortness of breath,
  • Difficulty in breathing,
  • Decreased oxygen saturation,
  • Giddiness/Dizziness
  • Sever malaise,
  • Severe myalgias,
  • Diarrhoea,
  • Headache, and
  • Loss of smell or taste,
  • Pneumonia.

Severe disease is characterized by an acute respiratory distress syndrome (ARDS), which has a 50-80% mortality in patients who require mechanical ventilation.

Most people recover quickly from common colds and flu, but recovery from coronavirus is very unpredictable.

Here, it is important to mention the Transmission of CORONAVIRUS also-

Like the cough and cold virus, the main transmission route of SARS-CoV-2 is thought to be by large respiratory droplets carrying viral particles, which are formed during coughing, sneezing, and speech. If the diameter of these droplet particles is >5-10 μm, they are called Respiratory Droplets, and if the diameter is <5 μm they are called Droplet Nuclei.

Respiratory droplets stay in the air for a few seconds and cover only a short distance before landing on the surfaces due to their weight. After mixing with the air, they behave as aerosols.

These aerosols can hang in the air and can remain active for up to 3 hours. They stay on the surfaces for even more time due to their lightness.

If a coronavirus patient coughs or sneezes, the maximum distance of transmission for SARS-CoV-2 aerosols could range from 4 meters to 8 meters.


Advice for the general population –

  • Cover nose and mouth with a tissue during coughing or sneezing and throw the tissue in the trash
  • Wash hands often with soap and water, especially after coughing or sneezing.
  • Alcohol-based hand cleaners or sanitizers are also effective
  • Avoid touching eyes, nose or mouth
  • Avoid close contact with sick people
  • Sick patients should be quarantined at home until at least 24 hours after they no longer have a fever without the use of paracetamol
  • Follow public health advice regarding school closures, avoiding crowds and other social distancing measures.
  • Get plenty of rest
  • Drink clear fluids such as water, broth, soups, or electrolyte beverages made to prevent dehydration.
  • Get admitted if symptoms are progressing and condition is worsening.

So, by the end of this blog, I believe that the readers not just will know about the two most common winter illnesses but also can easily differentiate between Common cold and Flu, which serves the purpose of writing this blog.



1. Ear, nose, throat textbooks

2. Cook GW. This winter, make the common cold less common. Asthma Magazine 2004;9: 9–11.


This blog including information, content, references, and opinions is for informational purposes only. The Author does not provide any medical advice on this platform.

Viewing, accessing, or reading this blog does not establish any doctor-patient relationship.

The information provided in this blog does not replace the services and opinions of a qualified medical professional who examines you and then prescribes medicines.

And if you have any questions of medical nature, please refer to your doctor or the qualified medical personnel for evaluation and management at a clinic/hospital near you.

The content provided in this blog represents the Author’s own interpretation of research articles.

7 thoughts on “Common Cold or Flu or Coronavirus: How to differentiate between these common winter illnesses?

  1. Yes,
    Dr. Sharad is very Intelligent, Good Behaviour, Caring & Loving Doctor.

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