Cold & flu health centre

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Common cold or allergies?

You've got a runny nose, a cough and congestion. So have you caught a cold or is it allergies? Unfortunately, it's often hard to tell, even for doctors, but here's some information that may help. Read on to learn more about the causes and treatment of cold and allergy symptoms.

What are colds and allergies?

Colds are caused by over 200 different viruses. When one of these viruses gets into your body, your immune system attacks it. Some of the effects of this immune response are the classic symptoms of a cold, such as nasal congestion.

The viruses that cause colds are contagious. You can pick them up when an infected person sneezes, coughs or shakes hands with you or if they are just in the air around you. Usually after a week or two, your immune system fights off the virus and you stop having symptoms.

Allergies are triggered by the immune system reacting to normally harmless substances, such as mould or pollen. Your body releases chemicals like histamine, just as it does when it’s fighting a cold. This can cause swelling in your nasal passages, a runny nose, coughing and sneezing. Allergies are not contagious, although some people may inherit a tendency to develop them.

Differences between colds and allergies

Characteristic	Cold	Allergy
Duration	3-21 days	Days to months to years, as long as you are exposed to the allergen
Time of Year	Most often in the winter, but possible at any time	Any time of the year, although the appearance of some allergens is seasonal
Onset of symptoms	Symptoms take one to three days to emerge after infection with the virus.	Symptoms can typically begin immediately after exposure to the allergen
Symptom	Cold	Allergy
Cough	Sometimes	Sometimes
Aches	Sometimes	Rarely
Fatigue	Sometimes	Sometimes
Fever	Rarely	Never
Itchy, watery eyes	Rarely	Often
Sore throat	Often	Sometimes
Runny or stuffy nose	Often; usually yellow mucus	Often; usually clear mucus

Although there are some differences, cold and allergy symptoms overlap quite a bit. The most important distinction is that colds don't last longer than 21 days. If you still have symptoms after three weeks, they may be allergy symptoms.

Colds and allergies: prevention and treatment

Because the causes of cold and allergy symptoms are quite different, preventing them requires different strategies.

To prevent allergy symptoms, avoid substances you're allergic to, called allergens, where possible. If you're allergic to pollen, for instance, avoid going outside on days when the pollen count is high. Here are some common allergens:

pollen
mould
animals
house dust mites.

Although there are no really reliable ways to prevent cold symptoms, you can try and minimise your chances of catching a cold. Keep your distance from people who have colds. Wash your hands often. To protect others, always cover your mouth and nose (with a tissue, rather than your hands) when sneezing or coughing.

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