Which symptom is associated with extensive swelling in allergic reactions?

Extensive swelling in allergic reactions is commonly known as angioedema, which specifically affects areas such as the lips and tongue. This symptom can occur due to the release of histamines and other chemicals in response to an allergen, leading to localized swelling. When an individual experiences swelling in these areas, it can be alarming and potentially life-threatening, especially if it leads to difficulty breathing or swallowing.

In contrast, skin discoloration may occur as a result of other skin reactions but is not typically caused by the same mechanisms that lead to swelling associated with allergies. Muscle cramps and rapid weight gain are unrelated to allergic reactions and do not characterize the typical responses seen in situations of extensive swelling. Therefore, swelling of the lips and tongue is the most direct indicator of extensive swelling associated with allergic reactions.