Allergic Contact Dermatitis: This condition is a common cause of erythema and edema, especially in the absence of discharge. It occurs due to an allergic reaction to substances like metals, latex, or certain chemicals in cosmetics or plants.

Irritant Contact Dermatitis: Similar to allergic contact dermatitis but results from a non-allergic reaction to an irritant, such as soap, detergent, or acid. It can cause erythema and edema without discharge.
Insect Bite or Sting Reaction: Reactions to insect bites or stings can cause localized erythema and edema. The absence of discharge is consistent with this diagnosis.
Cellulitis: Although typically associated with infection and sometimes discharge, early stages of cellulitis can present with erythema and edema without significant discharge.

Angioedema: A potentially life-threatening condition that can cause significant swelling of the skin and mucous membranes. It often presents without discharge and can be a medical emergency, especially if it involves the airway.
Necrotizing Fasciitis: A severe infection that can initially present with erythema and edema. Although discharge might not be present early on, this condition is critical to identify due to its high morbidity and mortality.

Erythema Multiforme: An immune-mediated condition that can cause target-like lesions and sometimes presents with erythema and edema. It is less common and can be associated with infections or medications.
Sweet Syndrome (Acute Febrile Neutrophilic Dermatosis): Characterized by fever, neutrophilia, and tender erythematous skin lesions. It's a rare condition that might not always have discharge and can be associated with systemic diseases or medications.