This condition is a dramatic, acute atopic reaction marked by the sudden onset of rapidly progressive urticaria and respiratory distress. a severe anaphylactic reaction may precipitate vascular collapse, leading to systemic shock and, sometimes, death.
CAUSES
The source of anaphylcatic reaction is ingestion of, or other systemic exposure to, sensitizing drugs or other substances.
Sensitizing Substances
such sensitizing substances may include serum, vaccines, allergen extracts, enzymes (such as L-asparaginase) hormones, penicillin and other antibiotics, salicylates, polysaccharides, diagnostic chemicals and radiographic contrast media, foods (legumes, nuts, berries, seafoods, and egg albumin) and sulfite-containing food additives, insect venom (honeybees, wasps, hornets, yellow jackets, fire ants, mosquitoes, and certain spiders) and, rarely, ruptured cyst.
A common cause of anaphylaxis is penicillin, which induces anaphylaxis in 1 to 4 of every 10,000 patients treated with it. Penicillin is most likely to induce anaphylaxis after parebteral administration or prolonged therapy and in atopic patients with an allergy to other drugs and foods.
SIGNS & SYMPTOMS
An anaphylactic reaction produces sudden physical distress within seconds or minutes (although a delayed or persistent reaction may occur for up to 24 hours) after exposure to an allergen. Severity of the reaction is inversely related to the interval between exposure to the allergen and the onset of symptoms. Usually, the first symptoms include a feeling of impending doom or fright, weakness, nasal itching, urticaria and swelling of the blood vessels.
Cardiovascular symptoms include low blood pressure, shock, and sometimes cardiac arrhythmia, which, if untreated, may precipitate heart failure.
espiratory symptoms can occur at any level in the respiratory tract and commonly include swelling of the nasal lining membranes, profuse watery discharge from the nose, nasal congestion and sudden sneezing attacks. Swelling of the upper respiratory tract, resulting in obstruction of the airways and difficulty breathing, is an early sign of acute respiratory failure, which can be fatal.
GI and genitourinary symptoms include severe stomach cramps, nausea, diarrhea, and urinary urgency and incontinence.
TREATMENT
Anaphylaxis is always an emergency and requires immediate medical care. If the doctor has prescribed an anaphylaxis kit to use in emergency, the kit contains everything that you need to treat an allergic reaction: a prefilled syringe containing two doses of epinephrine, alcohol swabs, a tourniquet, and antihistamine tablets. Notify the doctor at once if anaphylaxis occurs and use the anaphylaxis kit.
To prevent anaphylaxis, avoid exposure to known allergens. If you have a food or drug allergy, you must learn to avoid the offending food or drug in all its forms. If you are allergic to insect stings, you should avoid open fields and wooded areas during insect season and should carry anaphylaxis kit whenever you go outdoors. Wear a medical identification bracelet identifying your allergies.