Dieffenbachia is a common domestic plant. Oral contact with the plant generally causes slight effects, but when chewed it may result in painful oropharyngeal edema. Even though the mechanism through which this plant causes toxicity is not known, calcium oxalate crystals (rhaphides) and protease in the idioblast of the plant are considered to be the causes. Our aim was to show the lethal effects of a common domestic plant named Dieffenbachia.A 70-year-old male patient applied to our clinic with aphasia, dysphagia, sialorrhea, wounds on the lips and tongue, and swelling on the face. There was edema on his tongue, soft palate, uvula, anterior pharyngeal plica, epiglottis and aryepiglottic fold, and ulceration on the right side of his tongue, the right cheek mucosa, right-lower gingival, soft palate, tongue base, epiglottis anterior surface, and free edge.Dieffenbachia toxicity presents both minimal and serious problems, which can be life threatening, as in our case. Toxic cases resulting in serious clinical pictures due to Dieffenbachia are rare.