Drug allergy is the. General term. Forms of severe drug allergies reported for Fluconazole (diflucan) include anaphylaxis, stevens-johnson syndrome & toxic epidermal necrolysis. Other severe drug reactions are erythema multiforme & erythema nodosum. Diflucan (fluconazole) is a powerful drug with potentially severe side-effects often used for convenience. I prefer other antifungals for my patients.