Allergic reactions

Injury	Disease	Nutrition	Poison

Symptoms	Surgery	Test	Special Topic

Allergic reactions

Definition:

Allergic reactions are sensitivities to a specific substance, called an allergen, that is contacted through the skin, inhaled into the lungs, swallowed, or injected.

Considerations:

Allergic reactions are not uncommon. In fact, the immune response that causes an allergic reaction is similar to that which causes hayfever. Most reactions happen soon after contact with an allergen.

text continues below

Many allergic reactions are mild and can be treated at home, while others can be severe and life-threatening. They often occur more frequently in people with a family history of allergies.

Substances that don't bother most of us (such as venom from bee stings and various foods, medications, and pollens) can trigger allergic reactions in some people.

While first-time exposure may only produce a mild reaction, repeated exposures may lead to more serious reactions. Once a person is sensitized (has had a previous sensitivity reaction), even a very limited exposure to a very small amount of allergen can trigger a severe reaction.

Allergic reactions vary. They can be mild or serious. They can be confined to a small area of the body or may affect the entire body.

Most occur within seconds or minutes after exposure to the allergen, but some can occur after several hours, particularly if the allergen causes a reaction after it is partially digested. In very rare cases, reactions develop after 24 hours.

Anaphylaxis is a sudden and severe allergic reaction that occurs within minutes of exposure, PROGRESSES RAPIDLY and can lead to anaphylactic shock and death within 15 minutes if medical intervention is not obtained.

Causes:

Common allergens include: