Final answer:
The client's intention to limit fluid intake to three glasses per day while taking an oral sulfonamide for a UTI requires further instruction to ensure proper hydration and effective treatment of the infection.
Step-by-step explanation:
The statement by a client who has received a prescription for oral sulfonamide for a urinary tract infection (UTI) that indicates a need for further instruction is: "I will limit my fluid intake to about three glasses per day."Patients taking sulfonamide antibiotics should be advised to maintain adequate hydration to prevent crystalluria and kidney stones, which means consuming plenty of fluids, typically around 8 glasses or 2 liters of water per day. Not maintaining proper hydration can lead to complications and can affect the efficacy of the antibiotic treatment of the UTI.