Mesalazine and urinary stones

Patients who are using mesalazine (in high dosages) to treat an inflammatory bowel condition may develop urinary stones. A turbid deposit may then be visible in their urine. These urinary stones may consist of mesalazine for up to 100%, and are invisible on a general abdominal x-ray or CT-scan without contrast. Reducing the dosage may relieve the symptoms. Since 2019, the development of urinary stones, consisting of up to 100% mesalazine, has been included in the official product information for mesalazine. Although mesalazine therapy is started in a secondary care setting, a patient’s GP will often be the first to be confronted with the symptoms of urinary stone formation.