QHS (at bedtime)

How to read it

The Minnesota Board of Pharmacy gives q.h.s. as quaque hora somni, “every night at bedtime”, and h.s. as hora somni, “at bedtime”. The q is quaque, “every”, the same q as in QD. ISMP’s list of error-prone abbreviations flags one way of writing it, Qhs with a capital Q, because it is mistaken as qhr, “every hour”; Qn (nightly) is flagged for being mistaken as qh.

Also searched as: hs medical abbreviation, q.h.s., qhs meaning, qhs medical abbreviation.

How ISMP’s advice on QHS changed

The recommended wording has moved between editions of ISMP’s list. The 2015 list said to write “nightly” in place of qhs. The 2021 list offered “nightly or HS for bedtime”. The 2024 list recommends “QHS or qhs for bedtime”, keeping the abbreviation and flagging only the mixed-case Qhs.

HS: bedtime or half-strength

HS on its own has a second meaning. ISMP’s 2015 and 2021 lists gave HS as half-strength and hs as bedtime, each mistaken for the other, and the Minnesota Board of Pharmacy notes that h.s. “can mean half strength or hour of sleep”. The 2021 list’s recommended wording was “half-strength” for the one and HS in capitals for bedtime; the 2024 list no longer includes the entry. HS with AC, before meals, is on the AC and HS page.