What are allergies?
Allergies are a reaction your body may have to substances it sees as harmful or foreign.
Substances that can cause an allergic reaction are called allergens.
How do they occur?
Your immune system is your body’s natural defense against bacteria, viruses, and other foreign substances. Before you can have a reaction to a particular substance, your immune system must first be sensitized to it. Usually this means your body has to have been exposed to the substance at least once before. Once sensitized, your body will react every time you have contact with the substance. Many substances can cause an allergic reaction.
The most common are:
- Animal dander
- Dust and dust mites
- Insect stings
Allergens may cause different kinds of allergic reactions. The most common allergic conditions are hay fever, year round congestion, asthma, skin allergies and eczema.
Airborne allergens such as mold and the pollen of trees, grasses, and weeds cause hay fever.
Pollens, molds, house dust, and animal dander can cause year-round congestion; more mucus in your nose and airways; an itchy, runny nose; and itchy water eyes.
Pollens, molds, house dust, animal dander, and some medicines can trigger asthma attacks of wheezing and coughing.
Allergic reactions of the skin can have many possible causes. Examples of irritants that can cause allergic reactions when they touch your skin are hair or skin care products, nickel in jewelry and belt buckles, dyes in leather or fabric, and poison ivy or poison oak.
Eczema is a skin problem that may be caused by allergens. It often happens in people who are prone to allergies and asthma. It causes itching, dryness, and fine scales or flaking. Sometimes it causes mild redness.
It is also possible to have an allergic reaction to sunlight or temperature extremes.
Common foods that may cause allergy symptoms are shellfish, eggs, milk, nuts, and peanuts. Food allergies often occur in children, who may outgrow them.
It is not known why some people develop allergies to certain substances. Allergies run in families. However, not every family member may be allergic to the same things or have the same reactions. Some may have hay fever. Others may have asthma or eczema. Others may have all of these allergic reactions.
Sometimes an allergic reaction may be severe. This is called anaphylaxis and is a life-threatening emergency. It can affect the whole body, including your breathing, within minutes. Insect stings, certain foods, and drugs such as penicillin are some of the more common causes of severe allergic reactions.
What are the symptoms?
The symptoms of an allergic reaction depend on the type and severity of the reaction.
Common symptoms of an allergy are:
- Itchy, watery eyes
- Stuffy or runny nose
- Swelling—for example, swelling of the eyelids
- A rash or hives (raised, red, itchy areas on the skin)
- Stomach cramps
Some of the symptoms of a severe allergic reaction are:
- Trouble breathing, including wheezing
- Swelling of the lips, tongue, or throat
- Pale, cool, damp skin
- Drowsiness, confusion, or loss of consciousness
- Nausea and vomiting
How are they diagnosed?
Your primary healthcare provider will ask about your history of symptoms and examine you.
You may have tests to find out what you are allergic to. For most people the best tests are skin scratch or prick tests. For these tests tiny amounts of suspected allergens are put under your skin. Your primary healthcare provider then looks for reactions to the allergens. In some cases blood tests may help find what you are allergic to.
To identify a food allergy, your primary healthcare provider may suggest that you try to find which foods cause a reaction by not eating certain foods for a while. Then you can carefully try eating these foods again, one by one, to see if your symptoms come back.
How are they treated?
Depending on the type of allergy you have and your symptoms, your primary healthcare provider may prescribe:
- Steroid medicine
Using a steroid for a long time can have serious side effects. Take steroid medicine exactly as your primary healthcare provider prescribes. Don’t take more or less of it than prescribed by your primary healthcare provider and don’t take it longer than prescribed. Don’t stop taking a steroid without your primary healthcare provider’s approval. You may have to lower your dosage slowly before stopping it.
To treat or prevent breathing problems, your primary healthcare provider may prescribe:
- an inhaled bronchodilator
- other types of pills or inhaled medicine
Mild symptoms may not need treatment.
In some cases, your primary healthcare provider may suggest allergy shots. Shots may be recommended if your allergy symptoms cannot be controlled with medicine, especially if your allergies are severe. A mixture is prepared that contains the allergens found with your allergy tests. The mixture is injected into your skin in tiny but increasing amounts over the course of many months. Over time, the shots make you less sensitive to the allergens. Usually after 4 to 6 months of allergy shots you will start to have relief from your symptoms. You may need to keep getting the shots for 2 years or longer.
If you have severe allergies, your primary healthcare provider may prescribe an epinephrine emergency kit, such as EpiPen. You will need to always carry the kit with you. It contains a ready-to-use syringe of epinephrine. If you have a severe allergic reaction, a shot of this medicine can counteract allergy symptoms for a short while until you get medical care. You or someone with you can give you the shot. The kit is not intended as the sole treatment of an allergic reaction. Rather, it “buys” time while you wait for or get to emergency help.
If you have a severe allergic reaction, call 911 right away. Use the epinephrine emergency kit if you have one. Teach family members and coworkers how to help you if you have a severe reaction.
How long will the effects last?
Allergies last different amounts of time from person to person. Some people outgrow their allergies. Others have allergies all their life.
How can I take care of myself?
Follow your primary healthcare provider’s instructions.
Try to avoid the things you are allergic to.
If you tend to have severe allergy reactions, ask your primary healthcare provider about carrying emergency medicine, such as epinephrine. Wear an ID, such as Medic Alert bracelet, that lists your severe allergies.
How can I help prevent allergies?
There is no known way to prevent allergies. However, some research has shown that breast‐fed babies may be less likely to develop allergies and asthma.
If your family has a very strong history of allergies, you might try to avoid your family’s most common allergens. For example, you may need to stay away from cats. This might help stop you from becoming allergic to cats.
Cigarette smoke can make hay fever and asthma symptoms worse. You can help your symptoms by not smoking. It also helps to avoid being around others who are smoking. Children living in homes with smokers are more likely to have asthma.
Where can I get more information?
Many organizations provide support and information for people with allergies and asthma.
Here are a few:
The Canadian Allergy, Asthma and Immunology Foundation offers a variety of services including patient and consumer education information and pollen count reports and maps. Call 1‐ 613-986-5869 or visit their website at www.allergyfoundation.ca.
The Canadian Lung Association offers educational and support group information. Check your local telephone listings for a chapter near you, or visit their website at http://www.lung.ca
Anaphylaxis Canada was started in 2001 by a small group of people living with food and other allergies. Their hope is to create a safer society for a growing number of Canadians. Their mission is to inform, support, educate and advocate for the needs of individuals and families living with anaphylaxis and to support and participate in research. Visit them at: http://www.anaphylaxis.ca
The World Allergy Organization is an international organization of allergy and clinical immunology societies and organizations from around the world. It is dedicated to research and advance excellence in clinical care. Visit their website at www.worldallergy.org.
The MedicAlert Foundation Canada is a charitable organization which is the leading provider of emergency medical information services linked to customized medical bracelets and necklaces. Visit their website at www.nochildwithout.ca/.
For more information about local support groups in your community, contact your primary healthcare provider or local hospital.