Information Media Zone: Allergic Reaction

How Can I Prevent an Allergic Reaction to an Insect Sting?

Allergic reactions to insect stings can be prevented with allergy shots. The treatment is about 97% effective in preventing future reactions and involves injecting gradually increasing doses of venom that stimulate your immune system to become resistant to a future allergic reaction.

If you've had an allergic reaction, it's important to talk to an allergist, a doctor who specializes in the diagnosis and treatment of allergic disease. Based on your history and test results, the allergist will determine if you are a candidate for immunotherapy treatment.

How Are Allergic Sting Reactions Treated?

Severe allergic sting reactions are treated with epinephrine (adrenaline), either self-injected or administered by a doctor. Usually this injection will stop the development of a more severe allergic reaction.

In some cases, intravenous fluids, oxygen, and other treatments are also necessary. Once stabilized, you are sometimes required to stay overnight at the hospital under close observation. People who have had previous allergic reactions to an insect sting must remember to carry epinephrine with them wherever they go. Also, because one dose may not be enough to reverse an allergic reaction, immediate medical attention following an insect sting is still recommended.

What Is Hay Fever?

Hay fever is an immune disorder characterized by an allergic response to pollen grains and other substances. Also known as allergic rhinitis, there are two types: seasonal, which occurs only during the time of year in which certain plants pollinate, and perennial, which occurs all year round. (A related problem, nonallergic rhinitis, shares symptoms with hay fever but isn't caused by the type of reaction that's typical with allergies.)

Typically, if you suffer from hay fever in the spring, you're probably allergic to tree pollens. Grass and weed pollens may be causing your allergic reaction during the summer. In autumn, weeds may plague you, and fungus spores cause problems primarily from late March through November but can be present year round.

People with year-round (perennial) hay fever are usually allergic to one or more allergens found indoors. These include house dust mites, feathers, and animal dander (the tiny skin flakes animals such as cats and dogs shed along with fur), all of which may be found in pillows, and bedding, heavy draperies, upholstery, and carpeting. Another common allergen, mold, is usually found in damp areas such as bathrooms and basements.

What Causes Hay Fever?

If you suffer from hay fever (allergic rhinitis), it's because your immune system views harmless inhaled pollen or other allergens as dangerous substances invading your body. Your system overreacts, flooding your bloodstream with chemicals like histamine and leukotrienes, which inflame the lining of your nasal passages, your sinuses, and your eyelids and also set in motion other symptoms associated with hay fever, such as sneezing.

All of these symptoms are meant to protect your body either by trapping and expelling the allergen or by swelling body areas, such as the nasal passages, so the allergen can't enter. As a result of congestion in the veins in the lining of your sinuses, dark circles, commonly known as allergic shiners, may appear under your eyes. If you have perennial allergic rhinitis, they may be present all year round. The swelling of your nasal membranes may also close the sinus drainage openings, causing sinusitis. Rhinitis may also be associated with nasal polyps -- small, non-cancerous growths; nosebleeds are also common during hay fever attacks.

Hay fever is often an inherited trait (genetically determined). The majority of patients with hay fever have a parent or sibling who also has allergies. People with asthma or eczema (allergic dermatitis) are more likely than others to develop hay fever; and about one-third of those with allergic rhinitis also have at least mild, intermittent, allergic asthma.

What Are the Symptoms of an Allergic Reaction?

Common symptoms of an allergic reaction to inhaled or skin allergens include:

Itchy, watery eyes
Sneezing
Itchy, runny nose
Rashes
Feeling tired or ill
Hives (a rash with raised red patches)

Other exposures can cause different allergic reactions:

Food allergies. An allergic reaction to food allergens can also cause stomach cramps, vomiting, or diarrhea.
Insect stings. The allergic reaction to a sting from a bee or other insect causes local swelling, redness, and pain.

The severity of an allergic reaction’s symptoms can vary widely:

Mild symptoms may be almost unnoticeable, just making you feel a little “off.”
Moderate symptoms can make you feel ill, as if you’ve got a cold or even the flu.
Severe allergic reactions are extremely uncomfortable, even incapacitating.

Most symptoms of an allergic reaction go away shortly after the exposure stops.

The most severe allergic reaction is called anaphylaxis. In anaphylaxis, allergens cause a whole-body allergic reaction that can include:

Hives and itching all over (not just in the exposed area)
Wheezing or shortness of breath
Hoarseness or tightness in the throat
Tingling in the hands, feet, lips, or scalp

Anaphylaxis is life-threatening and requires immediate medical attention. Symptoms can progress rapidly, so head for the emergency room if there’s any suspicion of anaphylaxis.

What Happens During an Allergic Reaction?

First, a person is exposed to an allergen by inhaling it, swallowing it, or getting it on or under their skin. After a person is exposed to the allergen, a series of events create the allergic reaction:

The body starts to produce a specific type of antibody, called IgE, to bind the allergen.
The antibodies attach to a form of blood cell called a mast cell. Mast cells can be found in the airways, in the intestines, and elsewhere. The presence of mast cells in the airways and GI tract makes these areas more susceptible to allergen exposure.
The allergens bind to the IgE, which is attached to the mast cell. This causes the mast cells to release a variety of chemicals into the blood. Histamine, the main chemical, causes most of the symptoms of an allergic reaction.