A woman is diagnosed with primary dysmenorrhea and is prescribed ibuprofen as part of her treatment plan. When teaching the woman about using this medication, which instruction would be important for the nurse to emphasize?

"It is normal for your bowel movements to be black."

"Take the medication on an empty stomach."

"Add an aspirin to the regimen if you do not get relief right away."

"Start taking the medication before you first get your period."