This patient should be treated with high-potency glucocorticoid ointment. She has pruritic linear red papules and plaques concentrated on exposed areas 1 day after exposure to a vine, which is typical of rhus dermatitis. Rhus dermatitis is caused by urushiol resin in poison ivy, oak, or sumac.

A topical antibiotic such as bacitracin would be indicated for impetigo, a highly contagious bacterial skin infection, but not for rhus dermatitis.

Diphenyhydramine is an antihistamine. Contact dermatitis is a type IV hypersensitivity reaction that is mediated by lymphocytes and not a primary histamine process. Therefore, an antihistamine would be ineffective.

Because this is an intensely pruritic eruption with localization on the hands and arms, a low-potency topical glucocorticoid cream would be unlikely to control her symptoms. In addition, ointments, which are preparations made up of approximately 80% oil and 20% water, would be less likely to cause a burning sensation in a patient with open skin compared with a cream, which is a preparation consisting of approximately half oil and half water.