When is It a Cold?
The "common cold" can be caused by one or more of over two hundred varieties of viruses, including rhinoviruses, coronaviruses, and adenoviruses. When one of these viruses infects you (through contact with someone else who has a cold), after an incubation period of about three days you may present the typical symptoms: scratchy throat, congestion, sinus drainage, and coughing. While you can come down with a cold any time of the year, it's more likely to occur during the winter, when more of us are indoors and in close proximity to one another. But the major difference between colds and allergies is duration. If your symptoms do not clear up within two weeks, you may be dealing with an allergy. Also, if your mucus is yellow, it's more likely that you have a cold than an allergic response.
If it is a cold, try easing your symptoms with natural remedies or over-the-counter decongestants and antihistamines, and with that time-tested formula of drinking fluids and getting extra rest.
When is It an Allergy?
An allergy is an overactive immune system response. Contact with an allergen, such as pet dander or mold, can cause immediate symptoms, like a runny nose, coughing, sneezing, or even an asthma attack as your body releases histamines and other chemicals to fight what it perceives to be a pathogenic invader. Unlike a cold, an allergic response will last until you are no longer in contact with the allergen. So, if your runny nose, congestion, and sneezing do not subside after a couple of weeks, it's likely an allergen is to blame. The mucus of someone suffering from allergies is usually clear, and the body aches and fever that may occur with a cold are typically not present with an allergic response. Itchy, watery eyes are more often a sign of an allergy, rather than a cold. And if you come down with a "cold" at the same time every year (for instance, as soon as the snow melts or when flowers bloom), you're probably looking at an allergy.
Primary treatment of an allergic reaction is by avoiding contact with the allergen, and trying antihistamines and decongestants for symptomatic relief. Severe allergies may require emergency care, particularly if you have difficulty breathing.
Because so many of the symptoms overlap, even doctors can have a hard time telling the difference between cold and allergies. But with these fine distinctions, you'll have an easier time gauging your treatment plan, and knowing when to keep your germs to yourself.
MayoClinic.com, "Cold or Allergy: Which is it?" https://www.mayoclinic.com/health/common-cold/AN01229
WebMD.com, "Is It A Common Cold Or Allergies?" https://www.webmd.com/cold-and-flu/cold-guide/common-cold-or-allergy-symptoms
BBC/Health, "The Common Cold" https://www.bbc.co.uk/health/physical_health/conditions/commoncold.shtml