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Prescription abbreviations

What HS means
on a prescription.

HS on a prescription means at bedtime. It comes from the Latin hora somni, “hour of sleep”, and Indian references give it as night time. The same letters can also mean half-strength, so the safety group ISMP now recommends writing QHS or “at bedtime” instead.

HS

at bedtime

hora somni, Latin for “hour of sleep”

  • Also: half-strength, a second meaning that safety groups warn about

Also written h.s.

At bedtime, or half-strength?

HS has been used for both, and each has been mistaken for the other. ISMP’s 2021 list advised writing HS in capitals for bedtime; its 2024 list recommends QHS or qhs for bedtime instead.

What HS doesn’t say

It says how often, not how much or exactly when. The amount, the time of day and anything about food come from the rest of the prescription, the label or the pharmacist.

Setting it up in AlongWell

AlongWell reads HS, “at night” and “before bed” as a bedtime dose, timed from your family’s bedtime in Settings (10:00 pm until you change it).

Questions

What does HS mean on a prescription?

At bedtime. HS comes from the Latin hora somni, “hour of sleep”. It can also mean half-strength, which is why safety groups advise against it.

Is HS the same as QHS?

Both mean bedtime; QHS adds “every night”. ISMP’s 2024 list recommends QHS for bedtime because HS can be mistaken for half-strength.

Sources

This page explains what an abbreviation means. It doesn’t say how much to take or when: follow what the doctor wrote, and ask your pharmacist if any part of a prescription is unclear.

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