Credit: Courtesy of Dr. Robert Nathan

Courtesy of Dr. Robert NathanRobert A. Nathan, MD, is a clinical professor of medicine at the University of Colorado Health Sciences Center and director of the Asthma and Allergy Associates and Research Center in Colorado Springs, Colo.

Q: What's the difference between asthma that is due to allergies and asthma that is not?

A: Allergic asthma is an overreactive immunologic response that occurs because a person's body makes too much of an immune system component called immunoglobulin E (IgE). People with allergic asthma are bothered by common allergens like animal dander, dust mites, pollen, mold, or cockroaches, and they are often allergic to more than one of these things.

When a person has asthma that isn't related to allergies, but is instead triggered by factors that act directly on the lungs, such as infections, exercise, cold air, pollution, and stress, they have non-allergic asthma. Many people with asthma have a combination of non-allergic and allergic asthma. Of the nearly 19 million adults in the United States with asthma, about half have asthma that's related to allergies. But just 20% of adults with asthma have symptoms triggered by just allergies alone.

Q: How can you tell if your asthma is due to allergies?

A: First and foremost is the medical history. If a patient says he only has symptoms when he's near a cat or dog, for example, or only during pollen season, it's likely to be due to allergies.

Q: How can you know for sure what's triggering your asthma?

A: Skin tests, also known as 'skin prick tests,' are the gold standard. They involve putting a tiny amount of the allergen into the very top layer of your skin. The area will then swell, itch, and turn red if you are sensitive to that allergen.

Q: Do you need to see an allergist or a pulmonologist to be diagnosed with allergic asthma, or can your primary care doctor do the job?

A: Pulmonologists deal with a myriad of lung diseases, but allergists deal primarily with asthma and other allergic conditions, so they are better prepared to diagnose and treat allergic asthma. Most importantly, we're trying to identify triggers and help the patient understand how to deal with those triggers. The primary care physician may suspect that asthma is related to allergies, but it's the allergist who can confirm the diagnosis by using objective measures, like the skin test.

Q: Is asthma harder or easier to treat if it's due to allergies?

A: Avoidance is the main way to treat any allergic disease. In a way, it's easier to treat allergic asthma than non-allergic asthma, because you can just stay away from the allergen. But this depends on what the allergen is, and how sensitive you are to it. The ace in the hole that patients with allergic asthma have that patients with non-allergic asthma don't have is immunotherapy, or as it's more commonly known, allergy shots. It is potentially curative, whereas medication can only address symptoms.

Q: Does allergic asthma ever get better on its own?

A: While some children will 'grow out of' their allergic asthma once they reach puberty, it's exceedingly rare for an adult's disease to go into remission.

Q: Can allergic asthma be life threatening?

A: It's rare but certainly possible, depending on the extent of exposure, how bad an attack gets, and how long it takes for you to get treatment. Every year, 3,500 Americans die from asthma, and some will have had allergy-induced asthma.

Q: Will allergy shots help? What do they entail?

A: Allergy shots, or immunotherapy, can definitely help, but they're a major commitment. For allergy shots to be effective, a person needs to visit an allergist regularly for several years. And while insurers typically cover immunotherapy, copayment costs can add up.

At first, a person undergoing immunotherapy will go to the allergist once or twice a week, for three to six months, receiving slightly larger amounts of the allergen with each visit. The shot itself is very quick, but patients must wait in their doctor's office for 20 to 30 minutes to see if a reaction occurs. After this initial phase, the patient's visits are spread out to every two to four weeks. This maintenance phase can take two to five more years. A person is considered to be free of an allergy if he or she can go for two years without symptoms, which in essence means not having to take allergy medication.

Q: At what age do people typically develop allergic asthma?

A: Usually symptoms start before age 10, but a person can develop allergic asthma at any point in his or her life. It's rare for someone in their 60s or older to develop allergic asthma for the first time.

Next Page: What are some risk factors for allergic asthma? [ pagebreak ]Q: What are some risk factors for allergic asthma?

A: Heredity is the main risk factor. Eighty-seven percent of people with allergies have some background of allergic disease in a family member.

Q: What allergens trigger allergic asthma?

A: Animal dander, dust mites, pollen, and mold spores. Cockroach pieces can also be a problem in parts of the country where these insects thrive.

Q: I'm allergic to my dog, but I can't bear to part with him. What can I do?

A: It would be best to keep the dog out of the house, but if that's not possible, keep him out of the bedroom. If you have forced-air heat, consider putting cheesecloth over the bedroom registers to block allergens. Wash your hands after petting and playing with the dog. And you may want to think about allergy shots.

Q: If I'm allergic to dust mites, do I really have to wash sheets in hot water or is warm water enough?

A: Dust mite allergies are best controlled by putting special mite-proof covers on mattresses and pillows, and by washing bedding in the hottest water available at least once a week. Water should be at least 130 to 140 degrees Fahrenheit, and the hotter it is, the more dust mites it will kill.

Q: What medications are used to treat allergic asthma?

A: The same medications are used to treat allergic and non-allergic asthma. There really aren't any studies of medications specifically for allergic asthma.

The backbone of therapy should be inhaled corticosteroids to treat inflammation. If that's not enough to control symptoms, a long-acting beta agonist or a leukotriene modifier, like Singulair, may be prescribed. Anyone with asthma should keep a short-acting beta agonist on hand for emergencies, but this should be used no more than once or twice a week, and less frequently if possible. Medications like Allegra can help keep seasonal allergy symptoms under control. Xolair (omalizumab) is a new drug that works by tying up the antibodies that cause allergies, but is only used in patients with severe disease because of its cost.

Q: Do people with allergic asthma need to take medications year-round, or is it OK just to take them during allergy season?

A: If asthma is clearly allergen-induced, it can be safe to have a drug holiday for a period of time. For example, a person with seasonal allergies who doesn't have non-allergic asthma probably won't need to take medication once pollen season is over. I will usually test pulmonary function outside of their allergy season to determine if a patient with seasonal allergic asthma may have non-allergic asthma as well.

Q: If someone feels fine, do they need to be taking their medications?

A: It depends, and it's something patients must discuss with their allergist or primary care physician. Some people need to take inhaled steroids regularly to keep their asthma under control, while others may have allergen-free periods when this isn't necessary. Just feeling good isn't a good reason to skip medication, because the lungs may still be inflamed.

Q: Is it possible to overuse a bronchodilator inhaler?

A: Yes it is. Bronchodilator inhalers are only for 'rescue' use, when a person truly needs help breathing.

Q: If so, how often is too often?

A: Anything more than twice a week, unless the inhaler is being used for exercise-related symptom prevention, is too much. Patients who need to use it more than twice a week need to reassess their asthma control therapy. Using bronchodilator inhalers several times a day increases mortality risk. Bronchodilators open the airways by relaxing the muscles around them, and overly frequent use can make it more difficult for these muscles to relax on their own. The lungs basically lock up.

Q: Are there some interesting new allergic asthma treatments on the horizon?

A: Drugs that block interleukins or inhibit the action of prostaglandins look promising. But I don't see anything ahead that will revolutionize the treatment over what we have now.

Q: Is there such thing as a 'hypoallergenic' cat or dog?

A: Not really. Dogs that may have a less allergy-provoking type of dander will still bring in dust, pollen, and mold from outdoors, and I still don't believe there are hypoallergenic cats. What we promote is frequent bathing of all types of animals.