This is Part 1 of a two part post on the similarities between the cold, influenza, seasonal allergies and what we know about coronavirus.

Trying to distinguish symptoms of a cold, flu, allergies or COVID-19 can be very confusing, if not impossible, as these illnesses have so many symptoms in common.  As we are entering early Spring, we are transitioning from cold and flu season….to allergy season.

The seasonal flu viruses (influenza A and influenza B), the common cold and COVID-19 are contagious viruses that can cause respiratory illness.

Allergies are not caused by a virus and are not contagious.  Certain individuals are “allergic” to certain substances or allergens.

Fever and Shortness of Breath

As you read the rest of the article, you should become increasingly confused.  It should become quite clear that there is no symptom unique to the common cold, the flu or Coronavirus (see chart).  Fever and shortness of breath are, so far, the two most important symptoms when it comes to screening individuals for possible infection as these are common symptoms of a viral illness.

Allergic reactions cause itching which is not usually seen in cases of viral illness and maybe a distinguishing symptom of seasonal allergies.

Symptoms of Allergies

Allergies are an overreaction of the immune system to substances such as pollen, dander shed by pets, mold, dust, and smoke. Allergies cause itchy eyes, sneezing, a stuffy or runny nose, and sometimes coughing, but not fever, chills, or severe muscle or joint ache.  

Allergic reactions are mediated by a chemical called histamine.  Histamine is the culprit that causes the common symptoms of allergies:  runny nose, sneezing, itchy eyes, itchy nose, etc. For instance, if you are allergic to pollen, pollen causes histamine to be released in your body causing the common symptoms of allergies.

Symptoms of Influenza and Cold

Symptoms of the flu are listed below.  Keep in mind that not all patients with the flu exhibit the same or all of the symptoms.  Colds are caused by viruses and share many symptoms with the flu. Perhaps fever is less common with a cold. Body ached may be more common with the flu.

According to the CDC people who have the flu feel some or all of the following symptoms:

  • Fever
  • Cough
  • Sore throat
  • Runny or stuffy nose
  • Muscle or body aches
  • Headache
  • Fatigue
  • Vomiting and diarrhea

Part 2 - Covid-19, Cold, Flu or Allergies? Will be published subsequently.