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Asthma and Allergies

Many people with asthma have allergies that make their asthma worse. Sometimes it is called “allergy asthma” or “allergic asthma”. If you have asthma and allergies, it’s important to:

  • Know what you are allergic to – Remove or reduce the things you are allergic to
  • Take asthma medications if needed – Allergy medicines can help with allergy symptoms, but are not likely going to help with your asthma symptoms
  • Know what to do if your asthma is getting worse – Follow your asthma action plan!

Allergy Symptoms

Allergies can cause many different symptoms. You may have one or more of these symptoms:

  • Itchy, watery eyes
  • Itchy, runny nose
  • Itchy skin
  • Eczema – irritated, inflamed areas of skin
  • Hives – swollen mounds on your skin
  • Dark circles under and around the eyes
  • A headache that keeps coming back
  • Shortness of breath
  • Wheeze
  • Cough
  • Diarrhea
  • Stomach cramps

What am I allergic to?

Each person has their own set of allergens. They can be allergic to one or to many things. Some allergens are easy to figure out – especially if you strongly react to them. Others can be more difficult to determine.

To find out what you are allergic to, see your doctor. Your doctor may refer you to an allergist – a specialist doctor who is an expert on allergies. The allergist will ask you many questions about your medical history and your home and work environments: where you live and work, what substances you handle, what floor covering, pets or plants are in your home, when you notice your symptoms getting worse, etc. The allergist will also do a skin prick or scratch test to see what you may be allergic to.

This test usually takes about 20 minutes and is done in the office of the allergist. The allergist will put tiny drops of possible allergens (things you may be allergic to) on the skin on your arm or back. The allergist may test you for many allergens at once, so you may have rows of tiny drops on your skin. The allergist will then scratch or prick your skin underneath each drop of allergen, so the allergen can get under your skin. The allergist will watch closely to see how your skin reacts to each scratch. There may be redness and swelling in some spots. Based on your skin’s reaction, the allergist will be able to determine what you are allergic to.

Common ingested allergens—things you eat or swallow:

  • Food and drink – Although many foods can cause an allergic reaction, the following foods cause most of the problems:
    • Peanuts
    • Tree nuts (eg. walnut, cashew, almond, hazelnut, etc)
    • Fish and shellfish
    • Milk
    • Egg
    • Soy
    • Sesame seeds
    • Wheat
    • Mustard
    • Sulphites
  • Medicines

Common inhaled allergens—things you breathe in:

  • Pollen from grass, trees, and plants
  • Dust and dust mites
  • Animal allergens from dogs, cats, mice, birds, etc.
  • Mould

Effects of Allergens

If you have asthma, allergens can make your airways red, swollen, and filled with sticky mucus. Your airways can react as soon as you inhale the allergen or several hours later.

Early phase reaction:

  • Right away you can have asthma symptoms like wheezing and feeling short of breath
  • Your airways may be extra-sensitive, and they can tighten as soon as you start breathing in allergens
  • These first symptoms can often be relieved by using a reliever inhaler (usually a blue inhaler)

Late phase reaction:

  • Several hours after you breathe in the allergen, you can feel a second wave of symptoms
  • These symptoms are caused by your airways gradually swelling (inflammation)
  • Since there is a delay before people feel this kind of symptom, it can be hard to recognize what it was that brought on the reaction
  •  Taking an asthma controller medicine (eg., an inhaled corticosteroid) on a regular basis will help to prevent this reaction from happening

Asthma and Anaphylaxis

Anaphylaxis is a potentially life threatening allergic reaction. If someone has both asthma and anaphylaxis, when they have an allergic reaction there is a higher chance that it will be more severe and dangerous.

Anaphylaxis can involve many parts of your body including:

  • Skin
  • Nose
  • Throat
  • Lungs
  • Stomach
  • Circulation system

An anaphylactic reaction can cause a severe asthma attack and a dangerous drop in blood pressure. If you are at risk for anaphylaxis, make sure you carry your epinephrine injectors with you always.

Common causes of anaphylaxis include:

  • Foods
  • Insect stings
  • Medications

Less common causes of anaphylaxis include:

  • Latex
  • Exercise
  • Allergy shots
  • Unknown causes

For more information on anaphylaxis, visit Food Allergy Canada.

If you have asthma and are at risk for anaphylaxis, it’s important to do the following:

  • Keep your asthma under control
  • Stay away from your asthma and anaphylaxis triggers
  • Always carry your emergency asthma reliever inhaler (usually a blue inhaler)
  • Always carry your epinephrine injector
  • It is also a good idea to join an emergency medical information service such as MedicAlert so that you can be identified as having anaphylaxis and asthma.

Allergy Treatments

The best way to treat allergy symptoms is to prevent them. Stay away from the things that cause your allergies. No treatment will work as well as avoiding the allergen in the first place. Although you cannot always avoid all your allergens (e.g. pollen), try to avoid as much as possible.

There are several allergy treatment options that can help. They can help reduce typical allergy symptoms, but are not generally shown to help with asthma symptoms.

Nasal allergy treatments – Nasal corticosteroids

  • You’ll need a prescription from your doctor
  • Spray it in your nose daily
  • It reduces the swelling inside your nose


  • You can buy antihistamines without a prescription (over-the-counter)
  • Antihistamines counteract the histamine released in the body, which causes many symptoms
  • Antihistamines may cause drowsiness


  • You can buy decongestants without a prescription (over-the-counter).
  • Decongestants can take away the congestion (plugged up feeling in your nose and sinuses).
  • Non-prescription nasal decongestant sprays may lead to worsening congestion if taken for more than three or four days.
  • Decongestants shouldn’t be taken by people with high blood pressure and heart problems.

Allergy shots

Allergy shots don’t work for every kind of allergy and they can take a while to start making a difference. Your doctor or allergist can tell you whether they think allergy shots are right for you. They will inject you with a little bit of the allergen that you’re allergic to so that your body learns to be less sensitive to it. Allergy shots can take many years to complete.