What does s.i.d. indicate in prescription dosing?

What does s.i.d. indicate in prescription dosing?

• A. once daily
• B. twice daily
• C. every 6 hours
• D. as directed

Answer: (A)

s.i.d. comes from the Latin semel in die, meaning one time in a day. It indicates that the dose should be given once every 24 hours, typically at the same time each day. This is different from dosing twice daily (two doses per day) or every 6 hours (four times per day). “As directed” means follow the clinician’s specific instructions on the label, not a fixed interval. So s.i.d. is best understood as dosing once daily.

s.i.d. comes from the Latin semel in die, meaning one time in a day. It indicates that the dose should be given once every 24 hours, typically at the same time each day. This is different from dosing twice daily (two doses per day) or every 6 hours (four times per day). “As directed” means follow the clinician’s specific instructions on the label, not a fixed interval. So s.i.d. is best understood as dosing once daily.