This episode explores the infectious diseases approach to rashes, skin lesions, and cutaneous manifestations of systemic illness. We review key diagnostic clues, high-yield dermatologic findings in infectious diseases, and life-threatening rash presentations clinicians must recognize early. Topics include erythema nodosum, Sweet syndrome, nodular lymphangitis, pyoderma gangrenosum, disseminated viral exanthems, necrotizing fasciitis, purpura fulminans, and ecthyma gangrenosum. Practical guidance is provided on describing skin lesions, identifying dermatologic signs of immunosuppression or acute infection, and differentiating benign from high-risk presentations in adult patients.