Are You Sick Or Do You Have Allergies? How to Tell the Difference

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It always seems to hit you overnight—you wake up sneezing with itchy, watery eyes and a scratchy throat. Allergy sufferers know these symptoms all too well, but for the rest us, it can be difficult to determine the difference between allergies and the onset of a nasty cold. “Allergy symptoms are often very similar to those of a cold or even the flu,” says Lisa Ashe, PhD, a board-certified internal medicine physician and the medical director Be Well Medical Group in Washington D.C. “In both cases you can experience congestion, coughing, body aches, sneezing, headaches and fever.”

The causes of allergies and illness, however, are very different. “Allergies are due to histamines, the chemicals caused by an overactive immune system,” explains Elizabeth Trattner, A.P., D.O.M., a board-certified doctor of oriental medicine and acupuncture in Miami, Florida. “When your body thinks that something harmless like dust or pollen is an invader, they respond and attack.” On the other hand, the common cold and seasonal flu are caused by viruses that are contagious, explains Dr. Ashe. You can catch them by touching an exposed surface, shaking hands, or simply being in a tight vicinity like an airplane.

So, how do you know when to suffer through your sniffles at work or when to avoid giving whatever you’ve come down with to your colleagues—and their kids? To save you the hassle of doctor’s visit, here are some telltale signs that allergies are to blame.

Your symptoms appear at a certain time

Cold and flu symptoms don’t come and go throughout the day, says Dr. Ashe. Instead, they stick around until your body is strong enough to fight them off. Allergies, on the other hand, are symptomatic of external factors, such as the environment. “It’s common to experience the worst allergies first thing in the morning, when pollen is the highest,” she says. “Additionally, if you only sneeze around cats or fresh cut grass, that may indicate a specific allergy.”

Your only symptoms are itchy eyes and an itchy nose with subsequent sneezing

These are the main symptoms associated with allergies. “Generally with a cold, you experience a wider range of symptoms—fever, runny nose, congestion and cough,” explains Dr. Ashe. With the flu, these symptoms may seem more intense or be accompanied by extreme exhaustion and aches. So, if you only have one or two and otherwise feel healthy, you may simply have allergies.

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Your symptoms are lingering but not intensifying

It’s helpful to take note of how long your symptoms last. “The symptoms of a cold typically last anywhere from three days to two weeks, but allergy symptoms can last even longer, depending on how long the trigger is in the air,” says Drew Bird, M.D., director of the Food Allergy Center at Children’s Health in Dallas. If your symptoms come progressively worse or unmanageable at home, you should visit your doctor.

You're the only one in the house who is sick

“Colds and the flu are both caused by viruses and are highly contagious,” Dr. Ashe explains. “If you’re suffering from allergies, you can not give it to someone else.” In other words, if you’re the only one sniffling and your roommates or significant other remain symptom-free, you’re probably not sick to begin with.

Your nasal discharge is consistently clear

As both Dr. Drew and Dr. Ashe point out, the nasal discharge from a cold or the flu is often yellow or green and has a foul smell, signifying that a person is fighting off a bacterial or viral infection. If the sufferer’s mucus is typically clear and has no odor, chances are he or she is suffering from allergies.