A 30-year-old Chinese female presented with progressive periorbital swelling of unknown cause and redness of her left eye. She was given an antibiotic eyedrop and oral cloxacillin to treat periorbital cellulitis. The clinical picture did not improve and she returned with swelling of the fellow eye. We stopped the medication and sent her to a dermatologist because of the abnormal periorbital skin pattern. Her diagnosis was Paederus dermatitis. Intramuscular dexamethasone was administered due to severe periorbital edema. The skin lesion was improved one week later. The ophthalmic manifestations of Paederus dermatitis are periorbital dermatitis, conjunctivitis and persistent epithelial defects. The challenge in diagnosis of this condition is that it can mimic other diseases, such as infectious periorbital cellulitis and Herpes viral infection. Therefore, a clear appreciation of the clinical manifestations will lead us to the proper management of the condition and minimize complications.