Which of the following is a common precaution included on a prescription label?

The choice "Take with food" is a common precaution found on prescription labels, particularly for certain medications that can cause gastrointestinal irritation or might require food for better absorption. This instruction helps optimize the medication's effectiveness and minimizes potential side effects, such as nausea or stomach discomfort.

For instance, some medications are better tolerated when taken with food, which can buffer the stomach lining and prevent irritation that might otherwise occur on an empty stomach. This guidance not only enhances patient compliance but also informs the patient on how to take their medication safely.

Other potential answers may not apply as broadly. "Use only if symptoms persist" is more context-specific and is not generally considered a standard label instruction. "For external use only" applies specifically to topical medications and would not be universal across all prescriptions. Lastly, "No known side effects" is misleading, as almost all medications can have side effects, and such a statement would not typically appear on a prescription label. Therefore, "Take with food" stands out as a widely applicable and important precaution.