What are the differences among COVID-19, the flu, cold, and allergies?

COVID-19 Symptoms

Clarissa Chan, PharmD

This season, pharmacists should review the differences among COVID-19, influenza, the common cold, and seasonal allergies since many of the signs and symptoms are similar. Here’s what pharmacists need to know to guide patients in identifying and seeking relief for their illnesses.

How is the flu different from COVID-19?

The flu is caused by influenza A and B viruses. Like COVID-19, flu spreads via respiratory droplets when interacting with infected people in close contact through the eyes, nose, and mouth.

Both COVID-19 and the flu may present asymptomatically, or with mild or severe symptoms two to fourteen days after exposure to SARS-CoV-2 virus or one to four days after exposure to an influenza virus, respectively.

Although the most common signs and symptoms of COVID-19 are fever, cough, and fatigue, different variants of COVID-19 may cause symptoms inconsistent with classic complaints. Flu and COVID-19 symptoms are very similar, so diagnosis from signs and symptoms alone is likely to be inaccurate, according to the Mayo Clinic.

In-office or at-home test kits can be used to determine a definitive diagnosis.

Like with COVID-19, immunocompromised, medically complex, and older adult patients with the flu can require hospitalization for supportive therapy. It is also possible to become infected with both COVID-19 and the flu at the same time.

While there is only one FDA-approved drug—remdesivir—for the treatment of COVID-19, there are several FDA-approved treatment options for the flu—including oseltamivir phosphate (Tamiflu–Genentech, Inc.),  peramivir (Rapivab–BioCryst Pharmaceuticals, Inc.), and baloxavir marboxil (Xofluza–Genentech, Inc.).

According to CDC, if the flu is treated within two days of symptom onset, antiviral medications can lessen fever and flu symptoms and reduce the duration of the flu by one day.

What are the differences between the common cold and COVID-19?

The common cold is often caused by rhinoviruses and is an airborne infection like COVID-19. Individuals with a cold typically have mild symptoms. While patients with COVID-19 often exhibit symptoms of cough, sore throat, runny or stuffy nose, tiredness, muscle aches, fever, and loss of taste or smell, individuals with colds mainly have a cough, sore throat, and a runny or stuffy nose.

 Cold symptoms usually appear sooner than COVID-19 symptoms—after one to three days following exposure to a cold-causing virus, according to the Mayo Clinic.

Although there is no cure for the common cold, patients can purchase OTC cold remedies like decongestants and pain relievers to relieve mild ailments. Symptoms typically resolve within three to ten days, or up to a couple weeks, after onset.

How are seasonal allergies different from COVID-19?

Unlike COVID-19, the flu, and the cold, allergies are not caused by viruses. Seasonal allergies are immune responses triggered by allergen exposures—such as from seasonal tree or grass pollens. The most common symptoms are typically runny or stuffy nose, itchy eyes, and sneezing. Although COVID-19 patients sometimes experience shortness of breath or difficulty breathing, people with allergies do not usually experience breathing issues unless they have an underlying condition like asthma.

Allergies can generally be prevented by avoiding offending allergens or, if unavoidable, by taking OTC or prescription antihistamines, nasal steroid sprays, and decongestants to dampen the body’s immune response to allergens.

Accurate identification is key to successful treatment of these conditions. Pharmacists should always encourage patients to reach out to their local pharmacist or health care provider with any questions and concerns, especially if they suspect they have signs and symptoms consistent with COVID-19. ■