How do you tell the flu from a cold or allergies?

You usually notice it as you pour your morning coffee. The guy in the next cubicle or office doesn’t sound so good. He’s coughing and sniffling as he types away, hoping you won’t notice. You ask him if he’s doing OK even though you know what he’s going to say.

“I’m great. It’s just allergies,” he says with a hoarse voice in between coughing fits.

Those “allergies” turn out to be the flu and before you know it you’re burning four sick days (or worse, vacation days) because Larry couldn’t self-diagnose and refused to go to the doctor.

Don’t be that guy.

It’s important to get your annual flu shot and to wash your hands regularly Click To Tweet

I asked primary care physician and general internist Dr. Natalie Dryden for advice on how to distinguish between a cold or allergies and the flu – for which you should go to the doctor immediately.

“Distinguishing between allergies, a cold and the flu is not always easy,” she said. “While two are infectious illnesses (colds and flu) caused by viruses and the other is an immune response to some environmental trigger, the body often has overlapping and similar responses, so symptoms can be similar as well.”

Here are five clinical features that may help you tell the difference:

  1. Fever: The flu generally causes high fever fairly consistently, while viral colds don’t often cause fever, and if they do, it’s generally a low-grade fever. Allergies should never cause fever.
  2. Body aches: They tend to be very pronounced with the flu, and while they can occur with a common cold, they are typically mild. Body aches are not a common feature of allergies.
  3. Cough: A flu cough tends to be more severe than with a cold. Like a fever and body aches, a cough is much less common with allergies.
  4. Runny nose: Can occur in all three.
  5. Sore throat: Common with colds and flu. Typically people with allergies report having an itchy throat and not actual pain.

Keeping an eye on the seasons can also help clue you in on what may be going on. While all three conditions can occur year round, flu season typically occurs fall through spring in the United States. If you don’t believe me, just check the Centers for Disease Control and Prevention’s national flu map. Dr. Dryden says to keep in mind that people who travel abroad might be exposed to the flu since flu seasons occur at different times throughout the world.

CDC flu map
The CDC keeps an up-to-date map that shows which states have the highest number of flu cases.

Common colds mostly occur in the winter and allergies occur often with changes in the season depending on what a person is allergic to. Some people (like me, sadly) have then year round. Allergy symptoms tend to last as long as a person is exposed to an allergen or trigger while viral infections will usually last between a few days to two weeks.

It’s important to get your annual flu shot and to wash your hands regularly; especially during flu season.

The next time you feel an itchy throat and dull body aches coming on with a fever, consider what might be ailing you before you go to work and get your co-workers sick. Visit a doctor immediately. Your office mates will appreciate it and you’ll be back on your feet faster.