How to Tell the Difference Between Allergy and Cold Symptoms
Though allergies and the common cold have similar symptoms, they need different treatments. Here’s how to tell the difference.
Stuffy and runny noses come for us all. But if you haven’t been recently exposed to, say, a nose-blowing neighbor on an airplane or a shedding cat, it can be challenging to determine whether you’re dealing with a common cold or allergies.
Meng Chen, MD, a board-certified allergist and immunologist and clinical assistant professor in the department of internal medicine at Stanford University School of Medicine, says she commonly hears from patients that it can be hard to tell the difference between the two, because many of the symptoms overlap. There’s a scientific reason for those similarities, says Purvi Parikh, MD, a board-certified allergist and immunologist at NYU Langone Health in New York City. “Your body and immune system can react the same way to different invaders, so a virus can trigger the same response in your nose, throat, ears, and eyes as an allergen,” she says.
Fortunately—with the help of a doctor—you can figure out what’s causing your symptoms. Ahead, the experts share how they go about diagnosing patients with these everyday illnesses.
What are some of the symptoms of both allergies and colds?
Allergies can trigger a variety of symptoms, including watery and itchy eyes, sneezing, and a runny or congested nose, according to Chen. Someone with allergies may also have asthma-like symptoms, like coughing. Cold symptoms can be similar, including a congested and runny nose, sneezing, and coughing.
To add to the confusion, many people feel run down and sick when they have allergies. “Allergy symptoms seem to mimic cold symptoms because they are both a state of inflammation in the body, which can be very taxing,” she says.
Some of the symptoms do overlap, but typically, colds and allergies have their own tempo and time frame. “Quick onset of symptoms with environmental exposures, such as pets or pollen, are characteristic of allergies. Colds tend to come on a bit slower,” says Ralph Strauss, MD, a board-certified allergist and immunologist at Strauss Allergy & Asthma in Westbury and Commack, New York.
Though they come on rapidly, allergies can last weeks, months, and can be seasonal, depending on the allergen in question. Though they can come on fast (and sometimes resolve quickly if the allergen is removed), allergies can also last weeks. For example, if you’re allergic to cats, you might have acute and immediate allergy symptoms after you’ve been spending time with one — but Chen says those symptoms usually dissipate within a few hours of leaving the allergy-inducing environment. Pollen, meanwhile, can cause symptoms throughout the season. However, she says, there are also year-round allergies, like dust mites.
How can you tell if you have a cold?
If you have a common cold, you’ll probably have symptoms that aren’t associated with allergies in addition to the allergy-like symptoms. Cara Connors, M.D., a board-certified family medicine physician with the University of Tennessee Medical Center in Alcoa, Tennessee, says a cold can cause body aches and a severe sore throat, which don’t usually occur with allergies. Parikh also cites headaches, fatigue, and body aches as more typical cold symptoms. Allergies, meanwhile, might leave you feeling itchy.
Fever is another indicator of an infection, like the common cold. Kathryn Boling, M.D., a board-certified family medicine doctor at Mercy Personal Physicians at Lutherville in Lutherville, Maryland, says some people get a low-grade fever of up to 38 degrees with a cold, but not allergies. Plus, there’s also the tissue test: If you’re hawking up (sorry) phlegm, it’s more likely that you’re dealing with a cold. “With colds, you produce mucus [and] cough up stuff, which can be green, yellow, or clear,” says Parikh. “[With] allergies, you do not cough up any mucus or sputum.”
Another way to tell if you have a cold: Your symptoms don’t improve with antihistamines. “People usually get more relief from allergies with allergy medicines,” says Strauss.
To treat a cold, Connors recommends reaching for symptomatic care, like taking over-the-counter, multi-symptom cough and cold medicine. Rest and fluids are also important. “I find that if I can get people to stay at home when they initially feel like they’ve got a cold—if they take that initial one to two days to rest and drink more fluids—they get over it much more quickly,” she says.
How are allergies diagnosed?
A person’s response to allergy medications is one way to tell you that’s likely the problem. If you go to the doctor, your provider will ask you about the duration and time of your symptoms, even before doing a physical exam. Medical practitioners term this “taking a history,” and according to Strauss, it’s the most important part of any allergy or other diagnosis. “We cannot appropriately diagnose allergies or many other conditions in the absence of history,” he says. (He also advises steering clear of laboratories and other practitioners who offer a “‘test for everything’— [they] usually wind up wasting money and causing confusion,” he says.)
Next up is the physical examination. Boling says she looks inside a patient’s nose and can often tell they have allergies because the turbinates—structures in the nose that screen out particles and clean out and humidify the air that travels from the nostrils to the lungs — have a distinct, light pink, and squishy appearance. In the case of a cold, she says the nasal turbinates are usually red and swollen.
If you suspect you have environmental allergies, like an allergy to pollen or ragweed, an allergist will use a skin or blood test to help diagnose you.
How are allergies treated?
The primary treatment for allergies is over-the-counter antihistamines, according to Dr. Connors. Sometimes, she also recommends nasal steroid sprays to treat congestion and nasal inflammation. Dr. Chen says antihistamines can be used on an as-needed basis and typically work within an hour, while steroid nasal sprays are effective at preventing and treating allergy symptoms, but you have to take them daily for a week or two to see results.
Keep in mind that it’s important to use caution with some nasal sprays for allergies: According to Dr. Chen, oxymetazoline, a congestion-relieving ingredient found in some over-the-counter nasal sprays, can cause what’s known as rebound congestion if used for more than two or three days. Typically, steroid-based nasal sprays don’t cause this rebound effect. For some symptoms, saline nasal sprays can be helpful: “Nasal saline sprays do not relieve inflammation in the nose, but some people find them helpful if their nose feels dry,” she says.
If you’re going somewhere and you know you’ll be exposed to an allergen, Dr. Chen advises taking an antihistamine an hour beforehand. And if you’re not feeling well and you think it may be allergies, talk to a doctor, who can help you navigate the best course of treatment. “We know that allergies have a significant impact on people’s quality of life,” she says. “I commonly hear from patients that they didn’t realize how much better they could have been feeling all along.”
