q6h

q6h is a dosing interval used in medicine and pharmacology to indicate that a medication should be given every six hours. It is part of common shorthand such as q4h or q12h found on prescriptions and in medication administration records. The intention is to provide roughly four doses within a 24-hour period, though the exact start time is determined by the prescribing clinician.

In practice, a prescription written as a drug 500 mg q6h means the patient should receive 500 mg approximately every six hours, typically resulting in four doses per day. The first dose may be given immediately or at a specified start time, with subsequent doses scheduled at six-hour intervals. Some inpatient protocols anchor the schedule to natural day-night cycles (for example, 06:00, 12:00, 18:00, 00:00), but any anchor time is acceptable if clearly documented.

Clinical considerations include ensuring that the total daily dose does not exceed safe limits, particularly for drugs with narrow therapeutic ranges. Renal or hepatic impairment may require adjusting the interval to prevent drug accumulation. Dosing accuracy is essential; q6h can be misread or misapplied in busy settings, so many institutions prefer writing out “every 6 hours” or using a standardized schedule with explicit times.

q6h is most appropriate for drugs with relatively short, predictable half-lives where steady-state exposure over 24 hours is desired. It is not suitable for all medications, and some regimens may be better expressed with alternative intervals or continuous infusions.