A 45 year-old female with generalized erythema and mucosal erosions is likely suffering from which condition?

The clinical presentation of generalized erythema and mucosal erosions is suggestive of a drug reaction, particularly a hypersensitivity reaction such as Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS) or Stevens-Johnson syndrome (SJS)/toxic epidermal necrolysis (TEN).

Ampicillin, a beta-lactam antibiotic, is known to potentially induce hypersensitivity reactions, including skin eruptions and mucosal erosions in susceptible individuals. This can manifest as severe skin rashes covering large areas of the body accompanied by mucosal lesions, which aligns with the symptoms described in the patient.

Differentiating it from the other medications listed, while all can cause various side effects, neither prednisolone (a corticosteroid), aspirin (an analgesic and anti-inflammatory), nor hydrochlorothiazide (a diuretic) is as commonly associated with severe hypersensitivity reactions leading to generalized erythema and mucosal erosions. Thus, the symptoms presented most consistently correlate with an adverse reaction to ampicillin, making it the most plausible answer in this scenario.