Sulfonamide Quiz: Can You Spot The Allergy?

1. Which lab value should be monitored in patients receiving long-term sulfonamide therapy?

Hemoglobin and hematocrit

Serum creatinine and urinalysis

Liver function tests

All of the above

2. A patient with sulfonamide allergy requires treatment for toxoplasmosis. Which regimen is safest?

Trimethoprim-sulfamethoxazole

Pyrimethamine plus folinic acid

Sulfadiazine monotherapy

Repeat sulfonamide with close monitoring

3. Why is adequate hydration essential during sulfonamide therapy?

To prevent crystalluria and kidney stone formation

To enhance drug absorption

To reduce rash severity

To prevent hyperkalemia

4. A patient on sulfasalazine reports joint pain and fever. Which adverse effect is suspected?

Serum sickness-like reaction

Rheumatoid arthritis exacerbation

Unrelated viral infection

Sulfonamide-induced lupus

5. Which drug interaction is most clinically significant with sulfonamides?

Increased warfarin effect due to protein binding displacement

Decreased oral contraceptive efficacy

Enhanced metformin clearance

Reduced digoxin absorption

6. A patient reports itching and mild rash 3 days after starting sulfamethoxazole. What should the nurse document?

Certain sulfonamide allergy; discontinue immediately

Possible allergic reaction; notify provider for assessment

Normal side effect; continue monitoring

Late-phase anaphylaxis; prepare epinephrine

7. Which finding would contraindicate sulfonamide use in a pregnant patient?

First trimester exposure

Third trimester use near delivery

Gestational diabetes

Advanced maternal age

8. A patient on trimethoprim-sulfamethoxazole develops hyperkalemia. What is the likely mechanism?

Increased potassium intake from the drug

Trimethoprim inhibits renal potassium excretion

Sulfonamide-induced kidney damage

Enhanced intestinal potassium absorption

9. Sulfonamides are most commonly used to treat which type of infection?

Viral infections

Bacterial infections, especially urinary tract infections

Fungal infections

Parasitic infections only

10. A patient with a sulfonamide allergy needs prophylaxis for Pneumocystis pneumonia. What is appropriate?

Avoid all preventive therapy

Use atovaquone or pentamidine as alternatives

Give a low dose of TMP-SMX to build tolerance

Switch to a different sulfonamide

11. A patient reports a rash after taking trimethoprim-sulfamethoxazole (TMP-SMX). Which reaction is most likely?

Stevens-Johnson syndrome

Anaphylaxis

Maculopapular rash

Angioedema

12. A patient reports a history of allergy to furosemide. Is sulfonamide use contraindicated?

Yes, always contraindicated

No, loop diuretics and sulfonamides are structurally unrelated

Yes, all diuretics are contraindicated

No, but thiazide diuretics carry higher risk

13. Which sulfonamide derivative is primarily used for inflammatory bowel disease?

Sulfisoxazole

Sulfasalazine

Sulfadiazine

Trimethoprim-sulfamethoxazole

14. A patient on sulfasalazine reports yellow discoloration of skin and sclera. What is the most likely cause?

Acute hemolytic anemia

Drug-induced hepatotoxicity

Normal metabolite excretion (not pathologic)

Sulfonamide allergy reaction

15. Which patient population requires the most caution with sulfonamides?

Infants under 2 months old

Pregnant women in the first trimester

Elderly patients with renal impairment

All of the above

16. A patient with G6PD deficiency is prescribed sulfamethoxazole. What complication is most likely?

Hemolytic anemia

Hypoglycemia

Hyperkalemia

Metabolic acidosis

17. Which adverse effect is most specific to sulfonamide use?

Crystalluria and kidney stones

Hepatomegaly

Hypercalcemia

Thrombocytosis

18. A patient develops fever, sore throat, and oral ulcers after starting sulfadiazine. What is the priority nursing action?

Continue the medication and monitor vitals

Notify the provider immediately; hold the drug

Increase fluid intake to manage fever

Apply topical anesthetic to oral ulcers

19. Which statement about sulfonamide cross-reactivity is correct?

All beta-lactams are contraindicated in sulfonamide allergy

Thiazide diuretics have minimal cross-reactivity risk with sulfonamides

Loop diuretics share the sulfonamide structure

Sulfonylureas never cause reactions in sulfonamide-allergic patients

20. A patient with a documented sulfonamide allergy requires treatment for a urinary tract infection. Which antibiotic is safest?