Introduction: The medical leech (Hirudo medicinalis) has been used throughout the centuries and continues to be used today, mainly in reconstructive surgery and microsurgery. Easy access to these animals may entail an improper use of this therapeutic method by patients as a form of self-treatment.
Case report: A man who presented with skin erythema and oedema due to the application of a medical leech.
Discussion: Infection is considered the most common complication of hirudotherapy, even though bacteriological examination of leech applied by the patient showed neither bacterial nor parasitic infection. The skin lesions were probably of allergic origin; whether this reaction was due to substances released from the leech or as a consequence of reusing the same leech, remains to be determined.