What is a key difference between an allergy and an intolerance to medications?

The distinction between an allergy and an intolerance to medications fundamentally lies in the nature of the body's response. Allergies trigger an immune response, which can lead to potentially serious and life-threatening reactions such as anaphylaxis. This immune-mediated response means that the body incorrectly identifies a substance as harmful and activates the immune system to fight it off.

On the other hand, intolerances are typically characterized by non-immune adverse reactions that can result in discomfort or side effects, but usually do not initiate a direct immune response. These reactions can involve systems like the gastrointestinal tract, leading to symptoms such as nausea, vomiting, or abdominal pain, but they do not involve the severe implications associated with allergic reactions. Thus, the key difference outlined reflects the severity and nature of the responses: allergies can lead to serious complications, while intolerances generally cause milder, non-immune-related reactions.