Allergy

Allergy is not a disease in the typical sense. It is an exaggeration of the body’s natural immune defenses. Mild allergies can be annoying, and severe forms can be very serious or even deadly.

Allergies vary in the types of symptoms they cause and the methods to prevent and treat them. The type of allergy you have depends on the allergen that provokes your symptoms (such as mold or cat dander), the specific areas of the body affected by allergy symptoms (such as airways, skin or nose) and whether the reaction stays in one place or is triggered throughout the body. For example asthma, a type of allergy that may be triggered by a variety of airborne substances, is an exaggerated immune reaction confined to the airways of the lung. The symptoms of hay fever or seasonal allergies caused by pollen in the air are usually limited to the nose, eyes and sometimes the sinuses or the airways. On the other hand, an allergic reaction to an insect sting can trigger a severe response that affects the whole body. This response called anaphylaxis is potentially fatal.

Once you learn what type of allergy you have you can learn to prevent and treat it on your own. You can also learn how to recognize dangerous types of allergic reactions and when to get help.

General rules of allergy. Although each type of allergy behaves differently, some general rules apply:

1. Allergies always involve the immune system.

2. A reaction occurs after exposure to an allergen. The timing may be immediate – soon after contact with an allergen – or delayed – up to two contact (such as with poison ivy).

3. Prevention is just as important as treatment if not more.

The role of the immune system. All allergies are an immune reaction to a normally harmless antigen. An interesting quality of the immune system is that it is capable of learning. Each time you are exposed to an allergen, the immune system takes less time to react. Sometimes this reaction is more dramatic than the first, in some instances serious potentially life-threatening symptoms develop on subsequent exposure to an allergen.

Certain allergens are more likely to cause problems than others. It is important to avoid a second exposure if you have had a reaction in the past to insect stings, peanuts, latex or penicillin.

The role of the immune system in an allergy defines how that allergy is treated. All allergy treatments act by blocking immune system signals, such as histamines, or calming the immune system reaction (with corticosteroids).

The timing of the allergic reaction. Most allergic reactions occur shortly after you have been exposed to an allergen. For example, seasonal allergies are likely to worsen on the same day that the pollen count goes up. Or, if you have a cat allergy and visit the home of someone who owns a cat, you are likely to start developing an allergic reaction before you leave the house. However some allergic reaction take longer to occur. For example, some forms of contact dermatitis (such as poison ivy) may take more than a day or two to develop.

Prevention. Prevention is your best defense. Avoiding an allergen or treating your symptoms early is easier than trying to calm a reaction that has progressed out of control..

Common misconceptions about allergies. “All reactions to medications or foods are allergies”. There is a big difference between having an allergy to something versus an intolerance or side effects. People often use the term “allergy” loosely, referring to any reaction to medication or food as an allergy. Medication and food reactions can also be side effects or an intolerance (such as stomach or intestinal upset) rather than an allergy.

True allergies involve the immune system. Because immune system reactions can be dangerous or life threatening, it is extremely important to know if you have an allergy or an intolerance or side effects. Allergies to antibiotics such as penicillin or sulfa are often diagnosed by the appearance of a rash after taking the medication. If you take the medication a second time. The immune system reaction can be much more severe, even life threatening. On the other hand, an antibiotic such as erythromycin is commonly associated with stomach upset or diarrhea that is not related to the immune system. These symptoms are a side effect of this medication, not an allergic reaction. Because most symptoms from erythromycin are side effects, it is usually OK to take this medication or other related medications in the future. Always tell your doctor about any reactions to medications every time you are prescribed a medication.

“I am allergic to vaccines”. Another common misconception is that vaccines can cause allergic reactions. The site of vaccine injection can appear red, itchy or painful but this is usually the result of skin or muscle irritation or an infection at the injection site. The exceptions to this rule are vaccines that contain egg proteins. These vaccines can cause allergic reactions and should not be given to people with egg allergies.

The key to identifying true allergies is to give your health-care provider a precise description of your symptoms, including the amount of time between the reaction and the exposure to a specific medication, food or other medical treatment.

What causes allergies? Allergies result from a misfiring of the immune system which normally helps the body to fight off harmful viruses, bacteria and other microorganisms. In an allergic reaction the immune system perceives pollen, food or other allergens as a threat to health. The immune system defends against the invaders by creating antibodies that set off symptoms every time the allergenic substance enters your body or, in the case of a contact allergic reaction, touches your skin.

Common questions about allergies. Do children outgrow allergies? Food allergies to milk can be outgrown. On the other hand, children tend to keep allergies to peanuts, tree nuts, fish and shellfish into adulthood. If children do outgrow allergies it is often by age 3. Other allergy symptoms may improve as a child gets older nut new ones may develop.

Should a person move to another part of the country to escape the hay-fever season? Probably not. You could escape your current hay-fever symptoms by moving to another area but you could develop an allergy to a plant native to your new surroundings. Moving is usually not a practical solution to a pollen allergy.

Are allergies inherited? Yes. If one of your parents has a respiratory allergy like hay fever, you have a 30 to 50 percent chance of developing one, though not necessarily the same allergy. If both your parents have respiratory allergies, there’s a 60 percent to 80 percent likelihood that you will also develop an allergy.

Can breast-feeding prevent allergies? There’s no proof that breast-feeding protects the children of allergic parents from developing allergies at some point later in life but it could delay the onset of the allergies. Delaying the introduction of solid foods can further prolong the allergy-free period in babies who inherit a tendency toward allergy.

What is an anaphylactic reaction? Anaphylaxis is a severe, life-threatening allergic reaction – usually to foods, drugs or insect venom. The reaction can cause dizziness, breathing problems, an asthma attack, hives, a sudden drop in blood pressure or unconsciousness. If not treated promptly and correctly an anaphylactic reaction can be fatal. People at risk of these reactions should carry an emergency kit containing the drug epinephrine for use at the first sigh of symptoms.

How are allergies diagnosed? Your doctor may be able to diagnose an allergy on the basis of your symptoms and exposure to allergens. For instance, if you have allergy symptoms only during ragweed season, you probably are allergic to ragweed. If you have year-round symptoms, the problem could be dust mites, pet allergies or an allergy to a substance you come into contact with at work. You also may need some tests to identify the allergen. The simplest and most reliable is a skin test that scratches a drop of allergen extract into your skin. If you are allergic to the substance a reaction will develop within 15 minutes. A less accurate and more expensive blood test can be used when skin tests aren’t practical (if you have eczema or a skin condition that doesn’t permit testing) or would be dangerous (if you are severely allergic).

What is the most effective allergy treatment? Avoiding the substance that causes your allergy. This isn’t always possible if you have an allergy to common substances like pollen or dust mites, but you usually can reduce your exposure.