How can I tell if it's a cold or an allergy?

While both colds and certain allergies may share common symptoms, a cold is caused by a virus and an allergy is triggered by an allergen. Many people who suffer from allergic rhinitis ("Hay Fever") think they have colds, when in fact substances in their environments are to blame.

Allergic rhinitis results from an inflammation and irritation of the lining of the nose in response to an allergen. Common symptoms include a clear, watery nasal discharge, itchy nose, and sneezing with watery and itchy eyes. A cold is frequently accompanied by other symptoms such as sore throat and cough and only lasts 3 - 5 days, whereas allergic rhinitis tends to come and go and recur during the same season each year.

Numerous allergens may cause symptoms of allergic rhinitis: pollens are most common in the spring, grasses in the summer, and ragweed in the fall. Dust and household mites may produce year-round symptoms. Air pollution is also a factor.

Common outdoor allergens

• trees
• grass
• weed pollen
• ragweed
• sage or goldenrod pollen
• mold spores
• industrial pollution

Common indoor allergens

• house dust
• mold
• feathers
• wool
• cosmetics
• dander or furry pets
• tobacco smoke
• aerosols
• fresh paint

Allergens affect your immune system

When your immune system is exposed to allergens, it produces antibodies that attach themselves to certain cells in your body. These cells are found in your respiratory and gastrointestinal tracts, in your skin, and also in your blood. As part of the allergic reaction, these cells release potent chemicals such as histamine. This produces many of the familiar allergic symptoms seen in hay fever, for example -- a nose that's more like a leaky faucet than a breathing apparatus, runny eyes, itching and sneezing. Doctors often tell their patients to take antihistamines for allergies, because these medications help to counter the "histamine" effects. Result: no more runny nose and teary eyes.

The most common allergens

Although any environmental material can cause allergies, certain ones are encountered more frequently than are others. These include:

• Inhalants such as pollens, mold spores, animal products (dander, saliva, urine), house dust, and house dust mites.
• Foods such as cow's milk, eggs, chicken, shellfish, whitefish, peanuts, soybeans, wheat products, chocolate, celery, and all products containing one or more of these ingredients. Some individuals are allergic to food additives, such as sulfites (used as a preservative), nitrates/nitrites, parabens, and BHA/BHT - BHA. Also under scrutiny by researchers are Aspartame (Nutrasweet) and MSG (Monosodium glutamate).
• Drugs such as penicillin.
• Substances which touch the skin. These include plant oils, cosmetics and perfumes, nickel in jewelry or on buckles and under garment fasteners, hair dyes, topical medications including their additives, and occupational chemicals.

What can you do to prevent allergies?

You can't prevent allergies. About all you can do is to avoid symptoms by avoiding known allergens. Some physicians recommend you watch your child carefully after introducing a new food or medication. Be sure to tell your doctor if you are allergic to any antibiotics or other medications.
If you are allergic to common outdoor allergens -- such as pollen, trees or grass -- there are also some simple steps you can take to find relief:

• Keep your windows closed and avoid spending time outdoors when your allergies are acting up.
• Wear a protective allergy mask when you're doing yard work.
• Avoid fresh-cut grass.
• Be especially cautious on windy days.

Other pages in Health:

• Healthy Eating Pyramid
• Reflexotherapy
• Marijuana
• Biorhythm
• Homeostasis and metabolic control