A 78-year-old man with a history of pancolitis, after the treatment of dental abscess with oral antibiotics and local application of camphorated and mentholated chlorophenol (CMCP), presented with abdominal pain of 4-day duration, as well as hair loss in the area of moustache and finger nail lifting. He was already treated with rectal application of budesonide because of pancolitis, diagnosed 6 weeks ago and interpreted as an allergic reaction to clindamycin. For further investigation, we performed gastroscopy and colonoscopy, which showed the edematous mucosa with polypus-like changes of the whole mucosa of the stomach, duodenum, first part of the jejunum, distal ileum, complete colon, and rectum. The diagnosis was complicated and was achieved in synopsis with anamnestic details, such as endodontic application of camphorated chlorophenol. The patient symptoms abated after he commenced on mesalazine therapy.