Health Advice



Mayo Clinic Q and A: Flu, COVID-19 and seasonal allergies

Cynthia Weiss, Mayo Clinic News Network on

Published in Health & Fitness

DEAR MAYO CLINIC: My 14-year-old daughter has seasonal allergies that usually spike in the fall, as well as a love of the outdoors, so it is not uncommon for her to be congested and coughing. Last year, we home-schooled her, but now she is back in school in person. As we move from the fall into winter, how can I tell the differences between her allergies, a common cold, the flu and COVID-19?

ANSWER: Everyone experiences symptoms of congestion and cough from time to time. It's a common sign for many children, teens and adults, especially those who have seasonal allergies. However, as those are also symptoms of respiratory illness, it is important to be aware of the potential to spread germs to others, particularly since COVID-19, the common cold, seasonal allergies, and the flu share many similar symptoms.

-- Seasonal allergies and COVID-19

Unlike COVID-19, seasonal allergies aren't caused by a virus. Seasonal allergies are immune system responses triggered by exposure to allergens, such as seasonal tree or grass pollens.

While COVID-19 and seasonal allergies cause many of the same signs and symptoms, there are some differences. For instance, a fever will almost never accompany seasonal allergies, but it is a common sign of COVID-19. Also, muscle aches and fatigue, nausea, vomiting and diarrhea will likely not be present with allergies; whereas, they are common signs of a viral infection.

Also, while COVID-19 can cause shortness of breath or difficulty breathing, seasonal allergies don't usually cause these symptoms, unless you have a respiratory condition such as asthma that can be triggered by pollen exposure.


Treatment of seasonal allergies can include over-the-counter or prescription antihistamines, nasal steroid sprays and decongestants, and avoiding exposure to allergens where possible. Seasonal allergies can last several weeks.

-- COVID-19 and the common cold

Viruses cause COVID-19 and the common cold. COVID-19 is caused by SARS-CoV-2, a coronavirus, while the common cold is most often caused by rhinoviruses. These viruses spread in similar ways and cause many of the same signs and symptoms. However, there are a few differences. Specifically, nausea, vomiting and diarrhea are usually never present with the common cold.

While COVID-19 symptoms generally appear two to 14 days after exposure to COVID-19, symptoms of a common cold usually appear one to three days after exposure to a cold-causing virus.


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