A client who is taking an oral contraceptive receives a new prescription for erythromycin. Which instruction should the nurse provide to the client?

A. Use an additional form of contraception: Erythromycin can reduce the effectiveness of oral contraceptives by altering gut flora and affecting hormone metabolism. Using a backup contraceptive method during antibiotic therapy and for a short period afterward helps prevent unintended pregnancy. B. Avoid prolonged exposure to direct sunlight: Photosensitivity is not a common adverse effect of erythromycin, so limiting sun exposure is not a primary precaution for this medication. This advice applies more to drugs such as tetracyclines or sulfonamides. C. Stop the oral contraceptive immediately: Discontinuing oral contraceptives is not necessary; instead, a secondary method of contraception should be used to maintain pregnancy prevention while on erythromycin. D. Take the medications at least 12 hours apart: Spacing doses does not prevent the interaction between erythromycin and oral contraceptives, as the interaction is metabolic and not based on direct drug-to-drug binding in the stomach.