The Medical Minute: Allergy causes and treatments

March 30, 2005

By John Messmer
Penn State Family & Community Medicine
Penn State Milton S. Hershey Medical Center
Penn State College of Medicine

The grass is growing, flowers are blooming, birds are singing...and noses are sneezing. It's spring again and soon we'll see the return of seasonal allergies. Allergic rhinitis, sometimes called hay fever, occurs when the immune system responds excessively to a foreign substance, typically plant pollen. The word rhinitis refers specifically to inflammation of the nose, but allergies often affect the ears, throat, eyes and lungs as well. Allergies to plants and weeds are common, but allergy sufferers can react to many other things such as pet dander, dust, mold and mildew, smoke, latex and almost any other substance.

Allergic problems are not benign. Perhaps a quarter of all Americans are affected, resulting in 3.8 billion missed days of work and school per year at a cost of $4.5 billion annually. Allergies and asthma are closely related diseases. There are an estimated 5,000 deaths attributed to allergies each year according to the Centers for Disease Control and Prevention (CDC).

The root cause

Most allergies are provoked by pollens, tiny particles that trees, grasses and weeds release into the air. In Pennsylvania, trees release pollen in March and April, grasses release pollen in April and May and weeds release it May through June and again in August through October depending on the weather. Some people can react to proteins found in pet saliva, skin cells or urine, while the most unfortunate allergy sufferer is sensitive year round to dust mites, tiny organisms that live in houses no matter how clean. Mold, another common offender, is found in damp areas of the house and in fields, grasses and piles of vegetation.

In order to have a response to foreign material, called an allergen, a person with a genetic susceptibility is exposed to it, often several times. Although many people develop allergies in childhood, it is quite common for adults to have their first allergy problems later, even in middle age. Moving to a new area of the country might expose a person to an allergen for the first time. Someone might have a cat for years before beginning to be affected.

Here's how allergies develop: when an allergen lands on the nose or eyes, is inhaled or swallowed, the immune system cells attack the allergen and digest it. In a person predisposed to allergies, their body produces antibodies that attack the allergens. During the attack, the chemical histamine is released causing sneezing, itchy nose and eyes, congestion, and so on. Some people also release leukotrienes that increase the reaction and can contribute to asthma.

Allergies are diagnosed based on symptoms and family history. A physical examination and sometimes lab testing or skin testing confirm the diagnosis. Treatment starts with avoidance if possible. Today's airtight houses often trap mold spores and dust mites so increasing circulation and controlling humidity can be an important first step. Dust settles on draperies, carpets, stuffed animals and in blankets and comforters so eliminating these if possible will help.

If pollen is an issue, HEPA filtration can reduce much pollen, but they are not effective for everyone and every house. People with cat allergies ideally should give up the cat. Some have found it helpful to sponge the cat's fur regularly to clean off the dried saliva which is the source of the allergens.

Treatment

Medication can interfere with allergies and reduce the symptoms. Antihistamines have been the mainstay of treatment for decades. However, some antihistamines can cause sedation so care in driving is recommended. Loratidine, a less-sedating antihistamine, previously was available only by prescription but now is available over the counter.

Some people use Cromolyn nasal spray in response to allergies and related congestion, but be aware that Cromolyn is not an antihistamine. It can help block the allergic reaction but works best if used before symptoms develop. Prescription cortisone nasal sprays are very effective at blocking the allergic reaction. They have been used for more than 15 years and have been thoroughly tested. Used as directed, they are safe for the long term.

Montelukast, a drug previously used only in asthma, has helped some people with allergic symptoms. It has almost no side effects but does not work for everyone. Decongestants do not affect the allergic process but can relieve congestion. Some people cannot take them due to side effects, such as tremors, palpitations or difficult urination.

Sometimes allergy shots (immunotherapy) are used. Immunotherapy involves testing for the specific things one is allergic to and giving a series of injections of these allergens in gradually increasing concentrations to train the immune system not to react.

Anyone who has congestion, runny nose, itchy nose and eyes and sneezing and has been unsuccessful at home therapy should see a primary-care physician who can manage most people with allergies or refer to an allergist if needed. Allergies are common, and there is effective treatment for just about everyone.

For more information on allergies and related topics, go to http://www.cdc.gov/niosh/topics/asthma/ or http://www.aaaai.org/nab/

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Last Updated March 19, 2009