Sig. means what in prescribing instructions?

• A. at once
• B. stat
• C. s.o.s
• D. only when necessary

Answer: (D)

Sig. is the section of a prescription that tells the patient how to take the medicine—the directions for use, including what to take, how much, how often, and any special instructions. It comes from the Latin signatura, meaning the instructions to be written on the label for the patient. This is about how the medication should be used, not about urgency or emergency situations. A typical Sig. line can include an as-needed component, such as “take one tablet by mouth every 6 hours as needed for pain,” which is why the option describing taking the medication only when necessary best matches what Sig. conveys. The other options describe immediate or emergency timing, which does not reflect the purpose of the Sig. instructions.