Infectious eczematoid dermatitis is the development of acute eczema in response to purulent discharge from an infection. The primary infection is often a draining otitis externa or otitis media (acute or chronic). Other inciting infections include furunculosis, toe web infections, infected leg ulcers, mastitis, and blepharitis. The most commonly cultured bacterium is Staphylococcus aureus, followed by Streptococcus species. Pathogenetically, it is thought that bacterial proteins act as haptens to incite a hypersensitivity response.

Any age group and any body location may be affected; however, in children, the face and nares are most commonly involved, and in adults, the feet and legs are most frequently affected.