Fatalities associated with severe reactions including agranulocytosis, aplastic anemia and other blood dyscrasias occurred. Fatalities associated with severe reactions including Stevens-Johnson syndrome and toxic epidermal necrolysis occurred. Fatalities associated with hepatic necrosis occurred. Chemical similarities are present among sulfonamides, sulfonylureas, carbonic anhydrase inhibitors, thiazides, and loop diuretics (except ethacrynic acid). Risk of cross-reaction exists in allergy to any of these compounds (avoid use when previous reaction severe). Prolonged use may result in fungal or bacterial superinfection, including C. difficile-associated diarrhea and pseudomembranous colitis. Use with caution in G6PD deficiency (hemolysis may occur), and in hepatic/renal impairment. Fluid intake should be maintained ≥1500 mL/day, or administer sodium bicarbonate to keep urine alkaline (more likely to cause crystalluria as it is less soluble than other sulfonamides).