Question

"trimethoprim-sulfamethoxazole (septra) is prescribed for a client with cystitis. when teaching about the medication, the nurse instructs the client to:"

Answer 1

Cystitis is a disease or condition in which you have infection in urinary tract. 
trimethoprim-sulfamethoxazole (septra) is used for cystitis. when teaching about the medication, the nurse instructs the client to take this medicine until your infection is totally gone.
Because it is an antibiotic medicine and mostly you have to keep on antibiotics until you are totally recovered or the problem is gone.