Final answer:
Thiazide and loop diuretics can cause cross-sensitivity reactions with sulfonamides due to the sulfonamide moiety they contain, which is of utmost importance when obtaining a patient's allergy history.
Step-by-step explanation:
The class of drugs associated with a cross-sensitivity reaction with sulfonamides is thiazide diuretics and loop diuretics. These medications can trigger similar hypersensitivity reactions in patients with a sulfa allergy because they contain a sulfonamide moiety, which is the chemical structure that can cause the allergic reaction. This is particularly important to note when a nurse is obtaining an allergy history from a client. Having this knowledge ensures that healthcare providers avoid prescribing these drugs to patients with known sulfonamide allergies to prevent adverse reactions.