Something’s in the air this spring that’s making people wheeze and sneeze. It can make you fatigued, irritate your throat, and generally bog you down. But there’s a nagging question in early 2022: Is it pollen…or COVID?

The newest COVID surge in the U.S. is lining up with peak spring allergy season, and both conditions can manifest with the same symptoms, making it harder to tell whether you’re contagious or just suffering because you’ve been outside.

It’s especially tricky in 2022, since the third allergy season of the pandemic is by far the one with the fewest public health restrictions in the U.S. This week, major airlines along with Uber and Lyft made masking optional after a federal judge in Florida struck down the CDC’s federal mandate. And more people than ever are saying that the pandemic isn’t a crisis anymore, according to recent polling. That won’t help you tell if your sinuses are suffering or if it’s something else.

Another wrinkle in this year’s COVID/allergy season: the symptoms of the two maladies, which used to be clearly distinct, have started to bleed together.

“It's quite possible that people could have what they think are allergy symptoms and actually have COVID,” Dr. Robin C. Colgrove, an assistant professor of medicine at Harvard who works in the infectious disease division at Mount Auburn Hospital in Cambridge, Mass., told Fortune. “The obvious public health implication is that they could be walking around, not realizing that they’re contagious, and not distancing or masking.”

Which symptoms do you have?

“In simple terms, allergies generally occur when the immune system gets confused,” Dr. David Gudis, chief of the division of rhinology at Columbia’s Irving Medical Center/NewYork-Presbyterian Hospital’s department of neurologic surgery, told Fortune. The body, he says, can misinterpret environmental particles like tree and grass pollen as threats and initiate an immune response against them after they enter the body.

He outlines the most common symptoms for seasonal allergies: “runny nose, sneezing, nasal congestion, watery or itchy eyes, itchy nose, mouth, or throat, fatigue, and sometimes swelling or puffiness around the nose and eyes.”

“For the first year and a half of the pandemic, [COVID and seasonal allergies] were pretty much nothing like one another,” says Colgrove. The typical symptoms of COVID were fever and shortness of breath, but could also include coughing, sore throat, muscle aches, and loss of smell and taste—none of which are typical for seasonal allergies.

However, COVID symptoms are often more mild and therefore harder to pin down in people who have some form of resistance to the virus, whether through vaccination or previous infection.

The most recent Omicron variant also attacks the body differently than the original virus, leading to symptoms more in line with those of a common allergic reaction. Omicron “seems to be manifesting as an infection in the upper airways rather than lower airways,” says Colgrove. As a result, sore throat and runny nose have become more common COVID symptoms.

“The symptoms have started to overlap more than they were earlier in the pandemic,” he says.

Distinguishing between the two

There are key distinctions between the symptoms of COVID and seasonal allergies, even when there seems to be significant overlap. “Fevers and persistent coughing are uncommon symptoms for routine allergies,” says Gudis, and should therefore be the first indicator that your condition is not just the result of seasonal allergies.

He adds that nasal discharge from allergies is typically clear and watery for allergies, but thicker or discolored in response to the coronavirus. A cough associated with COVID is likely to bring up mucus or phlegm, while allergies provoke a dry cough, if any.

“While both allergies and COVID can result in decreased sense of smell, people with allergies will tend to notice that their sense of smell improves when their nasal congestion goes down. On the other hand, COVID can result in a decreased sense of smell even in the absence of nasal congestion or obstruction,” he says.

COVID also follows a predictable course of approximately two weeks, worsening steadily for the first five to seven days before gradually getting better, whereas “allergies, unfortunately, persist for a few weeks while pollen counts are high.”

“Any symptoms like shortness of breath or difficulty breathing should be taken very seriously, as these are unlikely to be due to allergies alone,” he says.

Dr. Amiinah Kung, an allergist at Northwestern Medical Central DuPage Hospital, told Fortune that differentiating between allergies and infections was a common question even before the pandemic because of symptom overlap.

Kung says that it’s especially important now for parents to take extra precautions with young children, who still have not been approved for a vaccine. “I would indicate to parents that they really should get kids checked out as soon as they can if they have any concerns about symptoms,” she says. “It's harder for kids to tell us their symptoms, so being able to examine them tells us if there's signs of an actual virus.”

This story was originally featured on Fortune.com