Is it an Allergy, a Cold or a Flu?

It’s sweater weather season! And given the fact that allergies, colds and the flu share many common symptoms, it can be difficult for you to tell if you’re coming down with a cold or the flu, or if you’re suffering an allergic reaction. In that regard, here are a few tips on how to gain a better understanding of what separates an allergy from a cold or flu, which in turn can help you to manage your symptoms more effectively.


What is an Allergy?

An allergy is an exaggerated response of your immune system to foreign substances that are generally safe. These substances typically come from sources such pollen , pet dander, mold and dust mites , and are called allergens.1 Fortunately, an allergy is not contagious.

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What is a Cold?

A cold is usually experienced when a virus enters your body. In response, your immune system proceeds to attack this foreign invader, triggering a cold.2 Symptoms of a cold, which include a runny nose and nasal congestion, are also symptoms of an allergy , which is why it can be difficult to tell them both apart. A cold, unlike an allergy, is contagious. The virus can spread through droplets in the air when someone who is sick coughs, sneezes or talks.2

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What is the Flu?

Influenza (more commonly known as the flu) is a highly contagious respiratory illness that attacks the body by spreading through the upper respiratory or lower respiratory tract.3 Both the common cold and the flu share similar symptoms, such as coughs, headaches and chest discomfort.4 The flu, however, can also cause you to experience more debilitating symptoms, such as a high fever that runs over several days, body aches, fatigue and weakness.

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Typical Characteristics of Allergies vs. a Cold

Typical Characteristics of Allergies vs. a Cold
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Learn Some of the Differences Between Allergies and a Cold

1. How Quickly Did Your Symptoms Strike?

Allergy symptoms tend to strike at one go when your body comes into contact with an allergen . Symptoms of a cold, meanwhile, usually appear individually and develop gradually over several days. The symptoms of a flu, quite interestingly, may only appear 2 days after the virus has entered your body, which means that you can potentially pass on the virus to someone else before your symptoms can even appear.

2. How Long Does it Take You to Recover From an Allergy, Cold or Flu?

A cold or flu may typically run its course within a 7-10 day period. Allergies, on the other hand, can last for a prolonged period of time, and can be triggered frequently if you are continuously exposed to allergens.

3. What Does The Colour and Texture of Your Mucus Look Like?

Runny nose and sneezing are common symptoms of both colds and allergies. But you can often tell the difference by looking at the color and texture of your mucus. If you have allergies, your mucus will typically be clear, thin and watery. If you have a cold, the mucus from coughing or sneezing may be thick and yellow or green. Yellow or green mucus could indicate an infection requiring medical attention.

4. Which of These 3 Illnesses Can Cause You To Suffer Body Aches and Pain?

A cold can be accompanied by slight body aches and pain, while a flu can cause extreme muscle soreness that can make it difficult for a person to move. Allergies, however, are not usually accompanied by body aches and pain.

5. When Does a Cold, Allergy or Flu Usually Occur?

Colds are more common during the colder months, but could also occur at any time during the year. Similarly, both indoor and outdoor allergies can happen all-year round in Singapore, as the country typically experiences hot and humid weather conditions that are accompanied by frequent rainfall throughout the year. A flu, on the other hand, can also occur all-year round, but tends to peak during the wet season.


  1. Allergies, Accessed 12 August 2020
  2. Treatment of the Common Cold in Children and Adults. American Family Physician. Accessed December 27, 2017.
  3. What Is the Flu?, Accessed 12 August 2020
  4. Cold Versus Flu. Centers for Disease Control and Prevention. Accessed Mar 30, 2022
  5. Achoo! Is the fear of contracting COVID-19 getting to you?, Accessed 12 August 2020