text: Procainamide and/or amantadine may have their plasma concentrations increased bilaterally or unilaterally.
  Clozapine and other antipsychotics — increased risk of haematological side effects
  Nucleoside analogue antineoplastics like azathioprine and mercaptopurine — increased risk of haematological toxicity
  Digoxin — increase in digoxin levels in a proportion of elderly patients
  Diuretics — elderly patients receiving thiazide diuretics are at a heightened risk for developing thrombocytopaenia while on co-trimoxazole
  Ciclosporin — patients who have received a kidney transplant and are receiving co-trimoxazole and ciclosporin concomitantly are at an increased risk of having a reversible deterioration in their kidney function.
  Spironolactone — concurrent use can increase the likelihood of hyperkalemia, especially in the elderly. The trimethoprim portion acts to prevent potassium excretion in the distal tubule of the nephron.
  Potassium aminobenzoate — effects of sulfonamides (like Sulfamethoxazole) inhibited.
  Laboratory tests — trimethoprim and sulfonamides have been reported to interfere with diagnostic tests, including serum-methotrexate and elevated serum creatinine levels, also urea, urinary glucose and urobilinogen tests.
  Overdose
  Likely signs of toxicity include:
  Nausea
  Vomiting
  Dizziness
  Headache
  Mental depression
  Confusion
  Thrombocytopenia
  Uremia
  Bone marrow depression
  Loss of appetite
  Colic
  Drowsiness
  Unconsciousness
  The recommended treatment for overdose includes:
  Administration of activated charcoal
  Stomach pumping
  General supportive measures
  Haemodialysis, which is moderately effective in clearing co-trimoxazole from the plasma.