How to Tell If You Have Allergies, Colds, or Flu

When you start sneezing or have a runny nose, you may think you’re coming down with a cold or the flu. But have you ever considered that it may be allergies? Common colds, the flu, and allergies share some symptoms, which make it hard to tell them apart. Each of these conditions have different treatments, so it’s important to know the difference among them and manage them accordingly.

What is an Allergy?

An allergy is an exaggerated response of your immune system to foreign substances that are generally safe. These substances are called allergens. They typically include pollen , pet dander , mold , and dust mites .1 Symptoms of an allergy include runny nose and sneezing.

What is a Cold?

A cold is an illness caused by one of over 200 viruses. You can get infected by another person who has a cold when they sneeze, talk, or cough close to you, or if you touch surfaces contaminated with their germs (e.g. door knobs, cutlery) and then touch your nose or mouth. After the cold virus enters your body, it attaches to the inside of your nose or throat. In response, your immune system proceeds to attack this foreign invader. Your throat and nose produce mucus and may get inflamed as your body fights the virus.2

What is a Flu?

Influenza, commonly known as the flu, is a highly contagious respiratory illness caused by influenza viruses. It infects the nose, throat, and sometimes the lungs. It is spread through infected droplets from a person who already has the illness. In general, flu symptoms can be quite debilitating and may include high fever, chills, and body aches.3 A person with the flu will generally need to be monitored to make sure that their symptoms don’t become worse.

Commonalities and differences among allergies, a cold, and the flu

Given the fact that colds, allergies, and the flu share similar symptoms, it’s important to know what these are, as well as their differences, so that you can manage the condition appropriately.4

CauseAllergensCold virus/esInfluenza virus/es
DurationFor as long as the allergens are present1-2 weeks1-2 weeks
Common symptomsRunny nose and sneezing, itchy and watering eyes, hives , wheezingRunny nose and sneezing, blocked nose, cough, sore throat, mild fever (occasionally)Runny nose and sneezing, sore throat, cough, chills, body aches, high fever, extreme fatigue
TreatmentLimit exposure to allergens.
Take a non-drowsy antihistamine such as Loratadine.
Rest, adequate hydration, medication to manage symptoms only if prescribed by a doctorRest, adequate hydration, antiviral or other medications to manage symptoms only if prescribed by a doctor


Additionally, here are a few questions that you can ask yourself to help determine if you have a cold, the flu or allergies:4

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 may only appear two days after the virus has entered your body, which means that you can potentially pass on the virus to someone else before your symptoms even appear.

2. What does the color and texture of your mucus look like?

A runny nose and sneezing are common symptoms of a cold, the flu and allergies. However, the color and texture of your mucus may reveal which condition you have. If you have an allergy, your mucus will usually present as clear, thin and watery. If you have a cold or flu, however, mucus may present as a thick, yellow, or green-coloured substance. If your mucus presents as yellow or green in colour, it could indicate an infection, which requires medical attention.

3. When does a cold, allergy, or flu usually occur?

Colds are more common during the wet season, but could also occur at any time during the year. Both indoor and outdoor allergies can happen all-year round. Flu can also occur all-year round, but tends to peak during the wet season.

While treatment for colds and flu may mean rest and hydration, manage allergies with antihistamine medications like Loratadine (Claritin®), which works in as fast as 15 minutes5, is non-drowsy vs. first-generation antihistamines and cetirizine6,7, and lasts up to 24 hours7.

ASC Ref. Code: B249P032922CS


  1. Allergies. The Mayo Clinic. Retrieved on November 23, 2021 from
  2. Common Cold. Johns Hopkins Medicine. Retrieved on December 8, 2021 from
  3. Key facts about influenza (flu). Centers for Disease Control and Prevention. Reviewed on August 26, 2021. Retrieved on November 24, 2021 from
  4. Cold, flu or allergy ? News in Health. Published in October 2014. Retrieved on November 24, 2021 from
  5. Sur, Denise K C, and Monica L Plesa. “Treatment of Allergic Rhinitis .” American family physician vol. 92,11 (2015): 985-92.
  6. Kawauchi, H.; Yanai, K.; Wang, D.-Y.; Itahashi, K.; Okubo, K. Antihistamines for Allergic Rhinitis Treatment from the Viewpoint of Nonsedative Properties. Int. J. Mol. Sci. 2019, 20, 213.
  7. Haria, Malini, et al. “Loratadine.” Drugs, vol. 48, no. 4, 1994, pp. 617–637.,