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Published on January 13, 2017

Cold, flu or allergy? What do you have?Cold, flu or allergy? What do you have?

Suffering from coughing, a runny nose and congestion? Could be a cold. Or maybe the flu. Or maybe it’s allergies.

These seasonal ailments share some common features, which can make it hard to know what you have and how to treat it.

“It’s easy for patients to be confused among the three,” said Paul Sklarew, MD, of the Allergy & Asthma Centers of Cape Cod. “I have to be honest and say that even sometimes doctors are confused. You have to look at more than one symptom to help you distinguish between a cold and allergies and the flu.”

For example, colds and allergies can look a lot alike.

“Cold symptoms can be mild enough that it’s hard to tell whether it’s a cold or allergies,” he said. “Sometimes it’s hard to tell.

“I’ve had bad sneezing fits for two or three days and I said, ‘I’m getting allergic to something.’ It was only on the fourth day that I got a low-grade fever and a scratchy throat and I realized it wasn’t an allergy. It was sneezing from a cold and it took a few days before I realized I was sick.”

Allergies and colds can both cause sneezing and a runny nose, but a low-grade fever means it’s a cold, while itchy eyes suggests it’s probably allergies, he said.

A common cold and a nasty flu can share some symptoms, but there are some key differences.

“Usually with the flu, you’ll have a higher-grade fever and more prominent muscle aches and pains,” he said. “Typically with colds and allergies you don’t feel that terrible. With the flu, you usually feel a whole lot worse. You just won’t feel like doing anything.”

Sometimes it takes a day or two before you can get a clear sense of whether what you have is a cold, allergies or flu.

“It’s good to figure out what you have, especially if it’s contagious,” he said.

If it’s a cold, you pretty much have to let it run its course, although some good old chicken soup might help you feel a little better.

“As a doctor, I’m kind of fatalistic about colds,” said Dr. Sklarew. “You just kind of tough it out. You can take some fever reducers to bring down the fever, and hot tea and lemon will soothe your throat. Some studies have shown that zinc lozenges can shorten the duration of a cold.

“For allergies, you can take an antihistamine like Claritin, Zyrtec or Allegra. They should relieve allergy symptoms, but they don’t necessarily help cold symptoms. If you’ve had lingering symptoms of what you thought was a cold and you take an antihistamine and you’re better in 24 hours, you should be checked for allergies.

“If it’s the flu, you can get a prescription medicine called Tamiflu. If you get it within the first 24 to 48 hours, it can shorten the duration of the flu and make symptoms milder.”

Cold, flu or allergies? Use this checklist for a self-diagnosis.

Symptom

Cold Flu Allergy
Mild fatigue yes no no
Extreme fatigue no yes no
Mild fever yes no no
High fever

(over 101)

no yes no
Coughing yes yes yes
Sore throat yes yes no
Runny nose yes yes yes
Watery eyes yes no no
Itchy eyes no no yes
Head or chest congestion yes yes yes
Muscles aches no yes no
Sneezing yes no yes