Which are common triggers of anaphylaxis?

• A. Insect stings, ingestion of nuts or shellfish, administration of penicillin or local anesthetic injections.
• B. Exercise-induced asthma only.
• C. Bacterial infection causing fever.
• D. Environmental pollen exposure only.

Answer: (A)

Anaphylaxis is a rapid, IgE-mediated allergic reaction that can cause widespread symptoms such as hives, swelling, wheezing, and a drop in blood pressure. It occurs when the immune system encounters a substance it has been sensitized to, leading to a sudden release of mediators like histamine from mast cells.

The most common triggers are substances people are commonly and reliably sensitized to: insect stings, foods such as nuts or shellfish, and certain medications given by injection, like penicillin or local anesthetics. These triggers are well known for provoking the full systemic response seen in anaphylaxis because they can trigger widespread mast cell degranulation throughout the body.

Other options describe conditions that are allergic or irritant reactions but not the typical life-threatening, systemic reaction of anaphylaxis. Exercise-induced asthma can occur and, in rare forms, be associated with anaphylaxis, but it is not among the classic triggers. Fever from a bacterial infection is not a trigger for anaphylaxis; pollen exposure mainly causes allergic rhinitis or seasonal asthma symptoms rather than the acute, systemic reaction of anaphylaxis.

So, the best match is the combination of insect stings, nuts or shellfish, and penicillin or local anesthetic injections as common triggers.