Medical Abbreviation Q4: Meaning and Usage in Prescriptions

q4 (or q4h) stands for the Latin quaque 4 horas — every 4 hours.

It directs medication administration frequency. Example: "Give morphine 2 mg IV q4h PRN pain."

Related abbreviations:

• q2h = every 2 hours
• q6h = every 6 hours
• q8h = every 8 hours
• q12h = every 12 hours
• qid = four times daily (not necessarily evenly spaced)

Always clarify timing with the prescriber if unsure; consistent intervals optimize therapeutic levels.