Australian Dental Council (ADC) Practice Test

The most characteristic allergic reaction to drugs is a skin rash accompanied by swelling of the lips and eyes, often classified as anaphylaxis or angioedema when severe. This type of response is a higher-level immune reaction, often mediated by immunoglobulin E (IgE), and is commonly associated with certain medications.

Skin manifestations, such as rashes, hives, or angioedema, are hallmark signs of a hypersensitivity reaction where the immune system mistakenly identifies a drug as a harmful substance. This leads to the release of histamines and other chemicals that cause localized swelling and inflammation, particularly around the mucosal areas, such as the lips and eyes.

While gastrointestinal distress, respiratory difficulties, and rapid heart rate can occur in drug reactions, they are more indicative of systemic issues or side effects rather than a direct allergic reaction. For example, gastrointestinal distress may occur due to an irritant effect on the stomach rather than an allergic mechanism, and respiratory difficulties could arise from various causes, including non-allergic drug reactions. Rapid heart rate can be a result of anaphylaxis but does not specifically characterize an allergic reaction on its own.

In contrast, the presence of a skin rash alongside facial swelling is a clear and common presentation that signifies