Q2H

Q2H is a shorthand notation used in medical contexts to indicate a dosing interval of every two hours. It is commonly seen in prescriptions, nursing orders, and electronic health record entries.

The notation stems from common pharmacologic shorthand, with “Q” representing “quaque” (every) and “2H” signaling a two-hour interval. It is used across administration routes—oral, intravenous, topical—and may be qualified by PRN to indicate as-needed dosing rather than a fixed schedule.

Safety and dosing considerations are important with Q2H. Frequent intervals can lead to rapid accumulation or exceeding daily dose limits, especially for drugs with narrow therapeutic windows. Clinicians tailor Q2H plans to the drug’s pharmacokinetics and the patient’s characteristics, including age, weight, renal function, and hepatic function. In pediatrics, weight-based dosing and careful monitoring are essential; in older adults or those with renal impairment, the interval or total daily dose may need modification.

Variations and documentation practices can affect interpretation. The notation appears in multiple formats, such as Q2H, q2h, or Q2h. Some institutions restrict Q2H to waking hours, while others apply it around the clock. When documenting, it is important to specify the start time, duration, and whether the interval applies to all doses or only as-needed administrations. Related notations include Q4H, Q6H, and Q8H.