Mesna (also known as Mesnex®) is a medicine used to prevent damage to the bladder that can be caused by some anticancer medicines. It is available as a clear liquid given into a vein (IV), but it can also be given by mouth in certain situations.

Possible side effects

  • Nausea
  • Vomiting
  • Diarrhea
  • Headache
  • Bad taste in the mouth
  • Hypersensitivity reaction, including rash, itching, hives, or trouble breathing

These are the most common side effects, but there may be others. Please report any side effect to your doctor, nurse, or pharmacist.

In case of severe side effects, call 595-3300. If you are outside the Memphis area, dial toll-free 1-866-2STJUDE (1-866-278-5833), and press 0 once the call is connected.

Special instructions

  • Mesna may not prevent bladder damage from anticancer medicines in all patients. Report blood in the urine to the doctor right away while you are receiving mesna.
  • It is important to drink lots of liquid while you are receiving mesna.
  • Mesna may cause a false-positive test for ketones in the urine.


This document is not intended to take the place of the care and attention of your personal physician or other professional medical services. Our aim is to promote active participation in your care and treatment by providing information and education. Questions about individual health concerns or specific treatment options should be discussed with your physician.

St. Jude complies with health care-related federal civil rights laws and does not discriminate on the basis of race, color, national origin, age, disability, or sex.

ATTENTION: If you speak another language, assistance services, free of charge, are available to you. Call 1-866-278-5833 (TTY: 1-901-595-1040).

ATENCIÓN: si habla español, tiene a su disposición servicios gratuitos de asistencia lingüística. Llame al 1-866-278-5833 (TTY: 1-901-595-1040).

تنبيه: إذا كنت تتحدث باللغة العربية فيمكنك الاستعانة بخدمات المساعدة اللغوية المتوفرة لك مجانا. .يرجى الاتصال بالرقم. 5833-278-866-1  (الهاتف النصي: 1040-595-901-1).