Achoo! What You Need to Know About Colds vs. Allergies

Sujan Patel, MD
Assistant Professor of Allergy and Immunology
New York Eye and Ear Infirmary of Mount Sinai

Achoo! What You Need to Know About Colds Versus Allergies

Sneezing, sniffling, coughing… are these signs of a cold or allergy? Many symptoms of the common cold and respiratory allergies can overlap, leaving patients confused as to the best course of treatment. However, there are some simple ways to tell these conditions apart. Causes and treatments differ for each, so knowing which one you have could mean the difference between getting well soon or feeling ill for weeks.

What Causes Colds and Allergies?

The common cold is a contagious illness caused by a virus that infects respiratory system cells. Your immune system fights the virus by releasing various chemicals, which, in turn, lead to cold symptoms, such as sore throat and nasal congestion.

Respiratory allergies are caused by noninfectious particles (allergens), such as pollen, animal dander, dust mites, and mold spores. Your immune system mistakenly reacts to these harmless substances as if they were attacking the body’s cells. Following a similar pathway, it releases other chemicals that create allergy symptoms, such as itchy eyes and nose.

Symptoms of a Common Cold

Generally lasting seven to 10 days, cold symptoms start off mild, progressively worsen over days, and diminish before resolving completely. The most common cold symptoms include:

• Sneezing that occurs in the early phases of a cold;
• A sore throat marked by a gritty sensation or pain that sometimes worsens with swallowing;
• A stuffy nose followed by a runny nose that tends to yield thicker nasal secretions than those caused by allergies;
• Coughing;
• A mild fever (101 degrees or lower) that is fleeting over one to two days;
• Feeling run down and unable to muster the energy for everyday activities.

Sometimes colds cause other symptoms that allergies generally don’t, such as nausea, diarrhea, body aches, or loss of appetite. Itchy eyes are rare to non-existent.

Symptoms of a Respiratory Allergy

Allergy symptoms can occur rapidly, sometimes in minutes, after being exposed to an allergen. They last for the duration of exposure to the allergen, whether a few minutes, several hours, or daily. The most common allergy symptoms include:

• Itchy eyes;
• Persistent sneezing that comes on in specific scenarios, such as being outdoors during certain seasons, or around a pet;
• A sore throat that feels itchy (sometimes patients with allergies will “scratch” their throats with the backs of their tongues, making a characteristic sound);
• A runny nose accompanied by itching and thin, watery secretions;
• Coughing that is less frequent than in colds, and usually related to the sensation of post-nasal drip from a nasal allergy;
• Feeling tired but still able to function, and having a “cloudy” thought process.

Fevers are rare to non-existent.

Cold Treatment

Colds are best treated with a “tincture of time.” A basic cold will run its course within seven to 10 days, the period your immune system needs to eradicate the cold virus. Instead of medication, doctors typically recommend what we call “supportive care” — getting plenty of rest and drinking lots of fluids.

Antibiotics are useless against the common cold since they fight only bacterial infections.

Antihistamines are not recommended, as research shows they are ineffective at alleviating cold symptoms. Some over-the-counter (OTC) cold medications, including pain relievers, decongestants, and expectorants, can help reduce symptoms, but will not decrease the duration of a cold and should not be used in children younger than four years. If you decide to try an OTC remedy, read the box or talk to your pharmacist to find one that most closely matches your symptoms.

Allergy Treatment

Untreated allergies can persist for weeks, potentially affecting your performance at work or school. Thankfully, allergy sufferers have a number of treatment options that can reverse the symptoms fairly quickly. These include antihistamine medications, nasal steroid sprays, allergy shots, and avoiding allergens when possible.

Antihistamine pills and nasal sprays block histamine, the chemical responsible for classic allergy symptoms like itchy eyes and nose. Nasal steroid sprays decrease inflammation and relieve symptoms in the nasal passages. Allergy shots, which are given over three to five years, “teach” the immune system to tolerate progressively greater amounts of an allergen, thereby diminishing symptoms for an extended (sometimes lifelong) period.

A note of caution: Some of the older allergy medications, such as diphenhydramine (also known as Benadryl), can make you drowsy, as can some OTC cold medications. If you have any questions or concerns about which medications cause drowsiness, ask your pharmacist for help.

When to See Your Doctor

If you think you have allergies or if your symptoms persist past 10 days, it’s a good idea to see your doctor for an accurate diagnosis and proper treatment. In addition to disrupting your life, untreated allergies can increase your risk of developing colds. And, colds sometimes lead to more serious infections, such as bacterial sinusitis, which would require a course of antibiotics.