| | Conditions & Treatments | Illness What illnesses do leeches cure? Leeches are not used in modern medicine to cure illnesses. Historically, leeches were used for bloodletting, a practice that is no longer considered effective. Illness - Related Articles How to Set Up an IV How to Care for Someone Who Has Vomited Tavanic Side Effects How Does Metal Affect the Results of a PET Scan? How to Order Drugs Online Cure for a Yeast Infection in the Mouth What Are the Causes of Ileus?