An acute allergic reaction occurs when the body reacts to a certain substance by releasing histamines. Signs of an acute allergic reaction include sneezing, runny nose, rash, swollen skin, hives, and difficulty breathing. Symptoms often begin within minutes of exposure. An acute allergy attack can occur when one is exposed to common allergens such as pet dander, shellfish, peanuts, wheat, and dairy. A severe and sudden allergic reaction can be fatal for the person suffering from the attack.
Some people are genetically predisposed to have acute allergy attacks. Early exposure to certain allergy-causing substances can cause someone to develop severe lifelong allergies against it. However, the genetic component is clear, as allergies tend to run in families. The body thinks that a harmless substance is a danger, so it produces reactions designed to repel and destroy the offender. If left untreated, an acute allergic reaction can lead to death.
Some very serious allergic reactions require medical assistance. Hives and itchy eyes are not life-threatening, but if the airway becomes restricted, anaphylaxis can occur. This very serious symptom causes a person to pass out and stop breathing. An autoinjector needle filled with epinephrine can sometimes prevent anaphylaxis, but it is less effective if it is given after a person passes out. Epinephrine relaxes the throat and airways to allow breathing to begin again.
Sometimes an allergic reaction can be controlled by the use of antihistamines. Loratadine, cetirizine, and diphenhydramine are over-the-counter medications that block the body's production of histamine and stop the body from overreacting. Antihistamines are produced in the form of pills and liquid suspensions. Some antihistamines can last up to 24 hours and do not cause drowsiness. People with allergies often carry antihistamine pills with them at all times.
If someone is having an acute allergic reaction with an airway obstruction, then they need immediate medical attention. Paramedics or doctors have the necessary tools to stop the progress of anaphylaxis. Epinephrine pills or needles usually won't help at this point, and over-the-counter medications aren't strong enough to combat this type of reaction.
People who suffer from severe allergies to certain substances should stay away from them, as the best way to prevent a reaction is to avoid the allergen altogether. Antihistamines taken before exposure to the allergen may help reduce the risk of anaphylaxis, but there is no certainty with these medications. The only sure way to prevent reactions is to stay away from the substance that causes the allergy.