It’s easy to diagnose yourself with a cold when you’re feeling unwell. But a cold isn’t always just a cold. It’s important to be able to tell the difference between the common cold (also sometimes called a head cold) and something more serious so you can get the medical attention you need.
If you think you have "just a cold" but are concerned it could be something more, it’s best to err on the safe side and visit your doctor. This is especially true if you have a chronic condition such as asthma, severe allergies, diabetes, kidney disease, HIV, or an autoimmune disease. The same goes for pregnant women and anyone under age 6 or over 65—the common cold affects these groups of people differently and can be more serious than it is for healthy individuals.
We spoke to doctors to find out the real differences between cold symptoms and flu symptoms—and other signs that tip them off that it’s more than a cold. Here, the red flags they look for.
You’ve had symptoms for longer than four days
The common cold tends to clear up on its own in three to four days, says Melisa Lai Becker, MD, site chief of emergency medicine at Cambridge Health Alliance. It starts with a scratchy throat, congestion, and runny nose, and then a cough usually develops. While your cough and post-nasal drip may linger, most head cold symptoms should disappear after four days.
"With a cold, you ultimately feel OK after a couple days of rest, hydration, and Kleenex," she says.
If symptoms last for longer, it’s possible you have something more worrisome, such as the flu or mononucleosis. To be safe, make an appointment with your physician.
Your symptoms seemed to go away… and then they came back
If you thought you recovered from your illness but your symptoms reappeared shortly after, it could be a sign of a rebound illness or "superinfection," says Navya Mysore, MD, a primary care physician with One Medical Group. You may have had a cold initially, but once your immune system was compromised, you developed something more serious—think strep throat, pneumonia, or a sinus infection. Book an appointment with your GP to determine whether or not you need additional treatment, such as antibiotics.
You recently returned from a big trip
Recent international travel is a red flag for doctors because it could mean you have a less-conventional infection they wouldn’t have normally considered, explains Stella Safo, MD, an internist at Mount Sinai Hospital who specializes in infectious diseases. It’s important to see a doctor if you have any symptoms after returning from a trip abroad.
You have a high fever
It is possible to have a fever along with a cold, but they’re not common—especially high ones. If you have a fever at or above 101 degrees Fahrenheit, it could be a sign of strep throat, says Dr. Lai Becker. Most patients with strep will develop a high fever in the first few days of illness, so be wary of sudden spikes in your temperature.
"Strep throat is one thing you really want to distinguish from a cold," she says. "Left untreated, it can cause rheumatic fever and lead to serious heart problems."
You’ve had a low-grade fever for days