These 2 Distinct Symptoms Will Reveal Whether You Have a Cold or Allergies

These two very different symptoms will likely indicate exactly what you are dealing with.

Sick African American woman working from home office using laptop drinking hot beverage covered with...
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For some people, transitioning from cold and flu season to allergy season can feel like you are jumping out of the frying pan and into the fire. Both conditions can result in perpetual runny noses and irrepressible coughing, and it can seem impossible to tell whether you should go for a decongestant or an antihistamine. However, according to immunologists, there are a few telltale signs that will help reveal what you are actually dealing with — and whether you are infectious.

Telltale signs of an allergy

Whether you’re sick from an infection or allergies, the immune system jumps into action, producing different sets of symptoms for both. Two signs are especially telling of whether you’re suffering from allergies or infection.

As an allergy indicator, “itch is really the primary differentiator,” says Christina Ciaccio, a pediatric immunologist at the University of Chicago Medicine. (If you’re feeling fancy, this condition has the formal name “pruritus.”)

Allergies cause itch — especially swollen, itchy eyes — because of chemicals your immune system releases called histamines, she says. Your immune system uses histamines to relay messages between cells, causing classic allergy symptoms like a runny nose, sneezing, and itch in the process.

Histamines come from a type of white blood cell called mast cells, says Bethaney Fehrenkamp, clinical assistant professor of immunology at Idaho WWAMI, a partnership between the University of Washington School of Medicine and the University of Idaho. Histamines bind to one of four histamine receptors to instigate a certain response; binding to H1 receptors activates itch.

To relieve allergy symptoms, many people take antihistamines, which work by blocking these receptors. An antihistamine will glom onto an H1 receptor, preventing a histamine from binding to it. By keeping histamine away from its receptor, then itchy skin never appears. But still, histamines don’t deserve a bad rap — they’re also crucial to regulating sleep-wake cycles, emotions, and learning.

In addition to scanning for itch, Ciaccio advises paying attention to your environment. Were you recently someplace where a dog may have visited? Is it early spring, when tree pollen starts up, or early summer, when grass pollen proliferates, or the start of flu season in October? If you’re traveling, you might be somewhere that favors pollination almost all year long, like Florida, Ciaccio says.

A sure sign of an infection

However, “if you’re fighting off a bacteria or a virus there is a decent chance you’ll develop a fever.” This regulated increase in body temperature helps immune cells perform at their best, as well as puts stress on the invading virus or bacteria.

Other symptoms, like aches and fatigue, may accompany a fever. “This is referred to as general malaise or ‘flu-like symptoms’ that are not present with allergy symptoms,” says Fehrenkamp.

But not every infection presents with malaise — perhaps only a cough, decongestion, and a runny nose.

Neither infections nor allergies are fun, but understanding the difference between how they present can help you determine the best treatment.

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