General Information

  • Urinary tract infections
  • Some superficial S. aureus infections (MRSA)
  • Stenotrophomonas maltophilia infections
  • Pneumocystis Pneumonia (PCP)
  • Nocardiosis
  • Prophylaxis for PCP and Toxoplasma gondii


  • Do not use for S. aureus bacteremia
  • Enterococci are resistant (even if reported as sensitive)
  • Streptococcus pyogenes: clinical failures occur even though may be reported as susceptible

Regular monitoring of kidney function and electrolytes if:

  • Prolonged use
  • Over age 65
  • Use of ACEi or ARB
  • K sparing diuretic
  • Baseline renal injury
  • Other risks for acute kidney injury/hyperkalemia
  • Renal injury and hyperkalemia, particularly in older patients (65 or older)
  • Sudden cardiac death: Higher risk in patients on angiotensin converting enzyme inhibitor (ACEi), angiotensin receptor blocker (ARB), K sparing diuretic (e.g. spironolactone)
  • Gastrointestinal upset common
  • Bone marrow suppression
  • Aseptic meningitis (rare)
  • Stevens Johnson syndrome/toxic epidermal necrolysis
  • Other rashes
  • Hepatitis
  • ACEi - Increased serum potassium level
  • Decreases cyclosporine
  • Methotrexate - Marrow suppression
  • Increases phenytoin
  • Increases INR with warfarin


  • Each mL of injectable contains sulfamethoxazole 80mg and trimethoprim 16mg


  • Each regular strength tablet contains sulfamethoxazole 400mg and trimethoprim 80mg
  • Each double-strength (DS) tablet contains sulfamethoxazole 800mg and trimethoprim 160mg
  • Each mL of oral suspension contains sulfamethoxazole 40mg and trimethoprim 8mg

Antimicrobial class: Sulfonamide - Antifolate

Pregnancy category: C

Average serum half life: 10 hours

Urine penetration: Therapeutic

Lung penetration: Therapeutic

CSF penetration: Therapeutic

Biliary penetration: Moderate