text: Mesna, sold under the brand name Mesnex among others, is a medication used in those taking cyclophosphamide or ifosfamide to decrease the risk of bleeding from the bladder. It is used either by mouth or injection into a vein.
  Common side effects include headache, vomiting, sleepiness, loss of appetite, cough, rash, and joint pain. Serious side effects include allergic reactions. Use during pregnancy appears to be safe for the baby but this use has not been well studied. Mesna is an organosulfur compound. It works by altering the breakdown products of cyclophosphamide and ifosfamide found in the urine making them less toxic.
  Mesna was approved for medical use in the United States in 1988. It is on the World Health Organization's List of Essential Medicines.
  Medical uses
  Chemotherapy adjuvant
  Mesna is used therapeutically to reduce the incidence of haemorrhagic cystitis and haematuria when a patient receives ifosfamide or cyclophosphamide for cancer chemotherapy. These two anticancer agents, in vivo, may be converted to urotoxic metabolites, such as acrolein.
  Mesna assists to detoxify these metabolites by reaction of its sulfhydryl group with α,β-unsaturated carbonyl containing compounds such as acrolein. This reaction is known as a Michael addition.  Mesna also increases urinary excretion of cysteine.