Colds and allergies can share many of the same symptoms. But they are very different conditions with different causes—and each require different treatment.1
If symptoms develop suddenly, and occur at about the same time every year, it’s probably an allergy.1 Allergies are caused by your body mistaking harmless substances—mould, pet hair, dust, and pollen—for germs, and attacking them.2,3 Allergies are the result of a chain reaction that starts in the body's defense system. This defense system acts like a perimeter fence around your body and reacts to anything it classes as an intruder. What’s more, the body remembers these ‘intruders’ and reacts whenever it encounters them.2,3
If you have an allergy to pollen for example, your body's defense system sees the pollen as an invader or an ‘allergen’ and reacts by producing antibodies. These antibodies then travel to cells that release chemicals, causing an allergic reaction. This reaction can cause symptoms such as nasal passage swelling, a runny nose, coughing or sneezing.2,3
Unlike an allergy, the common cold is caused by a virus.4 More often than not, this is due to a rhinovirus of which there are over 100 varieties.5 Cold viruses are with us year-round, regardless of climate or weather and colds can be spread from person to person by direct or indirect contact.4,5
| Symptom | Cold | Allergy |
| Stuffy/runny nose, sneezing | Often | Sometimes |
| Cough, sore throat | Often | Sometimes |
| Fatigue | Sometimes | Sometimes |
| General aches/pains | Sometimes | Never |
| Fever | Rarely | Never |
| Itchy eyes | Rarely | Often |
The fact that colds and allergies share many of the same symptoms often makes it difficult even for doctors to figure out which one a patient has. The most telling difference between colds and allergies may be duration; a cold rarely lasts longer than 14 days.7 Because there are over 100 different viruses which can cause the common cold,5 it may be possible however, to catch a ‘new’ cold – and a different virus entirely – while still having symptoms from the previous cold.
Medicines used to relieve the symptoms of the common cold include pain relievers and over-the-counter cold remedies, such as decongestants.4,8 You can get more information about treatments from your doctor or pharmacist.
Cold sufferers can often benefit from rest, plenty of liquids5 and may benefit from saline nasal drops or spray, which clear the nose and promote clearer breathing.9 The use of chicken soup dates back centuries, science has shown that it might help to clear blocked nasal passages and to reduce inflammation.10
The best way to prevent allergic reactions is to limit the exposure to allergens.2,11 Naturally, this can be easier said than done. Alternative allergy treatments can include over-the-counter medications, such as antihistamines, nasal sprays, nasal corticosteroids and decongestants.2 Some of these medications work by blocking the body's reactions to 'intruders'. As always, if you have questions seek advice from your doctor or pharmacist.
There are allergy tests available to determine exactly what the allergen trigger is for each person.11 If allergies are multiple and severe, you may need to see a specialist (allergist) to perform a series of allergy tests.
