Allergies

The immune system is made up of chemical pathways and cells within the body. When these are activated, an allergic response occurs. Allergies occur in response to normally harmless triggers known as allergens. The body of a person with an allergy responds to an allergen by attacking it. The immune response activates certain immune cells called mast cells. Mast cells trigger the release of chemicals known as histamine and leukotrienes which, in turn, act on tissues in the body and create the allergic response.

Allergies can affect nearly any part of the body. The nose, sinuses, eyes, lungs, and skin are most often affected. Symptoms may include:

• congestion of the sinuses and nose
• coughing
• itching of the eyes
• red, itching rash
• runny nose
• wheezing, which is a high-pitched sound heard when the person breathes

No one knows for sure why some people have allergies and others do not. Family history appears to play a part in a person's development of allergies.

Some common types of allergies include the following:

• allergic reactions to medications
• food allergies
• nasal allergies

There is little that can be done to prevent allergies from developing. Once they have developed, flare-ups can be reduced by allergy shots. These shots consist of tiny but gradually increasing doses of the substance to which the person is allergic. In response to the shots, the person's sensitivity to the allergen decreases.

Allergies are generally diagnosed with a medical history and physical examination. Blood tests and skin testing can be done to identify specific allergens.

Most allergic reactions simply cause extreme discomfort. They usually do not pose any long-term risk to the body.

Allergies are not contagious and pose no risk to others.

Medications used to treat allergies include the following:

• antihistamines, which help prevent the allergic response. Many antihistamines, such as diphenhydramine (i.e., Benadryl), are available over the counter. Loratadine (i.e., Claritin), cetirizine (i.e., Zyrtec), and fexofenadine (i.e., Allegra) are available by prescription.
• anti-inflammatory medications, which reduce inflammation in the airways. These include cromolyn (i.e., Crolom, Gastrocom, Intal, NasalCrom), nedocromil (i.e., Alocril, Tilade), prednisone, beclomethasone (i.e., Beconase, QVAR), and hydrocortisone.
• bronchodilators, such as albuterol (i.e., Proventil, VoSpire), to open airways and reduce wheezing
• decongestants, such as pseudoephedine or phenylephrine, to reduce nasal congestion

Avoidance therapy involves removing or reducing exposure to allergens. For example, problematic foods can be identified and avoided. Air cleaners and hypoallergenic covers on mattresses can reduce nasal allergies.

Antihistamines may cause drowsiness. Decongestants and bronchodilators can cause wakefulness.

Treatment of allergies is generally lifelong.

Any new or worsening symptoms should be reported to the healthcare professional.