Final answer:
The second most common drug reaction is exanthematous (morbiliform) drug eruption, a type of hypersensitivity reaction that presents as a symmetrical rash. Contact dermatitis, also a type IV hypersensitivity, is characterized by red, swollen, and itchy skin, but is not the second most common reaction. Drug induced acute urticaria, featuring itchy welts and hives, is also a frequent reaction but not the second most common.
Step-by-step explanation:
The second most common drug reaction is exanthematous (morbiliform) drug eruption. An exanthematous drug eruption is a type of hypersensitivity reaction that looks similar to a viral rash and typically starts 7-14 days after the introduction of a new medication. It presents as a symmetrical rash with red spots, usually on the trunk and extremities. This response is commonly seen as the body's immune reaction to certain medications like antibiotics or anticonvulsants.
Contact dermatitis is another type of delayed hypersensitivity reaction. It involves an immune response that can be triggered by substances like latex or poison ivy, and can take approximately one to two days after secondary exposure for a maximal response. It's characterized by red, swollen and itchy skin where the contact with the allergen occurred. Contact dermatitis is a type IV hypersensitivity reaction, which is T-cell mediated.
Drug induced acute urticaria is also a common drug reaction, presenting as itchy welts and hives on the skin. This reaction usually occurs quickly after drug exposure and is caused by the release of histamine from mast cells in the skin