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Trimethoprim / sulfamethoxazole


What is trimethoprim / sulfamethozazole?

Trimethoprim/sulfamethozazole is used to prevent or treat infections. It is also called SMX-TMP, Bactrim®, or Septra® or Sulfatrim® SMX-TMP is available as a green or white tablet and as a pink or white liquid. All are taken by mouth. SMX-TMP is also available as a clear liquid given by vein (IV).

Possible side effects of trimethoprim / sulfamethozazole


  • Nausea, vomiting
  • Diarrhea
  • Rash
  • Pain in abdomen

Later (usually more than a day after treatment starts)

  • Pain in abdomen
  • Low blood counts

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

In case of a severe side effect or reaction, call the doctor, nurse, or pharmacist at 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 for trimethoprim / sulfamethozazole

  • SMX-TMP can prevent a fatal pneumonia (Pneumocystis carinii) that can occur during chemotherapy. For the medicine to work well, you must take it exactly as instructed, every Monday, Tuesday, and Wednesday. Taking a smaller amount or missing a dose decreases protection. Giving more medicine does not increase protection.
  • Some patients may take SMX-TMP every day to treat certain infections.
  • Store this medicine at room temperature.
  • Take SMX-TMP with meals or on an empty stomach.
  • Shake SMX-TMP liquid well before taking each dose. Use an oral syringe or medicine cup to make sure you take the correct amount.
  • Be sure you drink plenty of fluids while you are taking SMX-TMP. Your doctor or nurse will tell you how much liquid you need to drink each day.


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).