How to Tell if It's Allergies, COVID or Another Virus

The US experienced a late-summer wave of COVID-19, which we can expect to continue into fall and winter when respiratory viruses typically thrive. While most people who catch COVID-19 will have a milder form, thanks to prior immunity and vaccination, older adults and some people with underlying conditions remain vulnerable to severe illness. 

And depending on what you're allergic to (it's ragweed and fall allergy season), you may still be experiencing some allergy symptoms. But given that allergies are not contagious, and viruses like COVID-19, the flu or the common cold are, it's important to know what you're ill with so you can minimize your chances of spreading it to others and get the proper treatment.

"It's very common that people who have allergies, they think they're having a series of viral infections," Dr. Geoff Rutledge, chief medical officer at HealthTap, told CNET last spring. And on the other end, some people have reported COVID-19 symptoms from newer versions of the virus that are typically linked to allergies, including pink eye. That can make it even trickier to know what you're down with, and that's why it's still important to test for COVID-19 if you plan on being around others. 

However, there are some symptoms and clues that are "very suggestive" you're experiencing a virus versus seasonal allergies, or vice versa, Rutledge said. 

Allergies (also called allergic rhinitis or hay fever) affect millions of adults and children each year and are caused by pollen or debris in the air that trigger an immune reaction and symptoms that follow -- sneezing or itchiness, for example. 

Viruses including COVID-19, respiratory syncytial virus (RSV) and the flu also trigger symptoms from a disease infecting the body and the immune system responding, but they can also result in secondary infections, such as sinus infections.

Here's what to know about the differences between allergies and a virus. 

Best Over-the-Counter Vitamins and Supplements Proven to Shorten a Cold See at Cnet

Quick tips to help check whether it's allergies or a virus 

In general, when telling one sickness apart from another: "It is always best to have a health care provider confirm the diagnosis if you are unsure," Dr. Jennifer Bourgeois, pharmacy expert at SingleCare, told CNET in an email last spring . That being said, there are some clues you can use to help yourself get the right medication or plan your week accordingly.

Read more: Your Decongestant Might Be Ineffective, FDA Panel Says 

If you have a fever, it's not allergies

While "fever" is in the name, hay fever does not actually cause a fever, according to the American College of Allergy, Asthma and Immunology. However, if you have a sinus infection or other bacterial infection, that may cause a fever and can be caused "sometimes secondarily" from allergies, according to Rutledge. 

If you're really itchy, it might be allergies

"Allergies typically cause itching of either the eyes, nose or top of mouth, which is not usually common in viral infections," Bourgeois said. It's important to note that, while it's hard to pin symptoms down to specific variants of COVID-19, there have been some reports of more cases of conjunctivitis or pink eye with the newer versions of the virus. Viruses and bacteria can also cause pink eye, which in turn can cause itching around the eye.

According to the Cleveland Clinic, other symptoms of allergic rhinitis besides itching include congestion, sneezing, headaches and sinus pain, dark circles under the eyes, increased mucus, postnasal drip (mucus draining down the back of your throat), trouble breathing and fatigue or generally feeling bad. 

Take a COVID-19 test 

This one's pretty simple, but the best way to find out whether you have COVID-19 or something else is by taking an at-home test, or a more accurate lab test in a doctor's office. This might be especially important if you plan on being around a person who's older or otherwise at higher risk of serious illness from COVID-19. Also: that "expired" COVID-19 test you have leftover from last winter might not be expired after all. 

Read more: Take 2 Minutes to Order 4 Free COVID Tests 

Take the antihistamine test 

For people who experience seasonal allergies, but aren't entirely sure if that congested feeling is from the same cold your friend had or the familiar allergies that usually kick in this time of year, Rutledge suggested what he calls a "therapeutic trial" of taking an over-the-counter antihistamine to see if that clears up your symptoms. 

"There are specific treatments that only work for allergies," he said, and antihistamines are one of them. Histamine is what your body releases when you have an allergy and your immune system is activated. Antihistamines work by blocking the effects of histamine and helping many allergy symptoms. On that note, if you have sinus pain or sneezing and your symptoms improve after you take a histamine, it might be safe to say you have allergies.

What are the most common COVID-19 symptoms?

While the US Centers for Disease Control and Prevention has a long list of COVID-19 symptoms, as does the World Health Organization, symptoms will depend on your age and other factors, like how severe of a case you have and which strain of COVID-19 is circulating. And according to Yale Medicine, the subvariant currently causing the most COVID-19 cases in the US, EG.5 or "Eris," does not appear so far to cause symptoms that are different than other versions of omicron that have been circulating for a while. 

The UK-based ZOE health study was a good reference for the "most popular" COVID-19 symptoms because its researchers were keeping track of how such symptoms change by collecting information from people with a positive test who shared their symptoms. However, a new list hasn't been compiled in a while. As of December 2022, the top 10 most common COVID-19 symptoms in the UK, according to ZOE, were: 

• Sore throat
• Runny nose
• Blocked nose
• Sneezing
• Cough without phlegm
• Headache
• Cough with phlegm
• Hoarse voice
• Muscle aches and pains
• Altered sense of smell 

COVID treatments 

Antiviral medications like Paxlovid may be prescribed for older adults and younger people who have a higher risk of getting severe illness from COVID-19 (for Paxlovid to work, you need to start the medication within the first few days of your symptoms appearing). 

To reduce the risk of illness before it starts, there's an updated vaccine targeting newer strains of the COVID-19 virus coming out this fall. More details on the booster will be available in September, including who should get one and when they should get it. 

Read more: New COVID Shots Are Available: Here's How to Find One 

What are some effective allergy treatments?

What kind of medication you need depends on which symptoms you have. 

"Each medication is designed to treat specific symptoms, so it's important to find the correct over-the-counter medicine in order to manage and relieve your symptoms," Bourgeois said. For example, antihistamines like Claritin or Zyrtec are standard allergy medications, but you could also find relief from a decongestant. 

In a pinch, a fever-reducing medication like ibuprofen might also work for allergies because they have anti-inflammatory properties, Bourgeois said.

You might even try stopping allergy symptoms before they start with a steroid nasal spray, according to Bourgeois. They do the work before you're exposed to the allergens in the air.

"It is best to begin the steroid nasal spray a couple of weeks before the allergy season that triggers your symptoms and continue throughout the duration of the season, as it's typically not required to use the steroid nasal spray all year long," she said.

If you choose to do a nasal rinse after symptoms and mucus sets in, Bourgeois referred to the CDC's guide for safely carrying it out with sterile material. 

Many people will manage allergy symptoms with help from their primary doctor or the right medication, Rutledge said, and they won't need further medical help. But if you're still not getting relief from your symptoms, and you've done some detective work into what's causing your allergies, then you might be a good candidate for in-clinic allergy testing or a follow-up appointment with a specialist to get to the source, according to Rutledge.