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How to tell if you have allergies or a cold

Bryn Mawr Hospital March 24, 2017 General Wellness By Michele Columbo, MD

Q: I’ve had this constant drip and nasal congestion for weeks. I find myself going through boxes and boxes of tissues, not to mention coughing and clearing my throat all the time. I thought I had caught a cold from a co-worker but now I’m thinking it could be allergies—which I’ve never had in my life. How can I tell if it’s cold or allergies, and how can I make it go away?

This is a great question and topic because a lot of people experience symptoms that can be caused by either colds or allergies, such as sneezing, coughing, and runny nose. It can be difficult to self-diagnose, especially if you’re an adult who has never had allergies before.

One way to understand the difference between colds and allergies is to understand that they are both immune system responses. When you have a cold, for example, which is caused by a contagious virus, your body goes to work attacking the foreign germs. This attack response is what produces swollen nasal passages, excess mucous, coughing and other common cold symptoms.

With environmental allergies, your immune system responds similarly, if not “mistakenly,” to dust mites, pollens, pet dander, and molds, fighting against them as though they were germs. When the body goes on the attack, it releases histamine and many other chemical mediators. Such substances can cause swelling and inflammation in the nasal membranes and eyes. The release of these substances causes stuffiness, runny nose, sneezing and coughing as well as itchy and watery eyes. Keep in mind, however, that when you have allergies, you generally won’t experience sore throat, fever, or body aches, as you might with a cold.

In spite of the similar symptoms, the length of time you have those symptoms is a good clue. A cold is generally done and over with in a few days, or at most a few weeks. Allergies on the other hand may last a few days, weeks, or even months, and they tend to turn on and off depending on where you are, such as indoors or outdoors or the time of the year.

Both colds and environmental allergies can lead to the condition known as sinusitis, in which you may experience symptoms like swollen nasal passages, excess mucous production, facial pain, pressure and low-grade fever.

Colds and allergies can often be treated with over-the-counter medications that address runny nose, sneezing and stuffiness. For an infection, antibiotics are sometimes necessary.

As you previously pointed out, there are many people who have never had allergies, but suddenly find that they have them as they get older. It is quite possible, and not unusual, to go through most of your life and then start having allergic reactions to environmental allergens or even to foods.

In your case, it certainly sounds like you’re dealing with allergies: the persistence of your symptoms and their duration are good indications that environmental allergies are their likely cause.

If you are experiencing symptoms that concern you or if you have a respiratory or sinus condition that just won’t go away, it may be time to visit your doctor. Your doctor will review your medical history and assess your symptoms. In many cases, you may be referred for additional testing and a visit with an allergist/immunologist who can diagnose and treat your condition.