The QHS medical abbreviation means every night at bedtime, so the medicine is taken once a day, just before sleep, night after night. It stands for the Latin quaque hora somni, "each hour of sleep," and is written QHS, qhs or q.h.s.
QHS is common on orders for cholesterol medicines, sleep aids, some antidepressants, eye drops for glaucoma and nighttime inhalers or ointments. It builds on HS, at bedtime, by adding Q for each or every. The Institute for Safe Medication Practices recommends QHS or qhs when a dose is due at bedtime. What its error-prone list warns against is the mixed case Qhs, which can be read as qhr, every hour, and qn, which can be read as qh. Here is how QHS reads in practice and how it compares with nearby terms.
At a glance
Stands for
Every night at bedtimeLatin origin
Quaque hora somni, each hour of sleepWritten as
QHS or qhs (preferred), q.h.s.Doses per day
One, taken at bedtimeSafety note
QHS and qhs are the ISMP forms; mixed case Qhs is error-proneSafer to write
QHS or qhs, or nightly at bedtime spelled outDo not confuse with
Qhs or qn, misread as qhr or qh (every hour), and QAM (every morning)
What the QHS medical abbreviation asks you to do
QHS gives both frequency and timing in three letters: once a day, and that once is at bedtime. It is how prescribers write a nightly routine. A person on a QHS medicine takes it each evening as part of getting ready for bed, and a hospital gives it during the evening medication round, usually around 21:00 or 22:00.
Bedtime timing is chosen for a reason. Some medicines cause drowsiness. Some cholesterol medicines have been traditionally dosed at night. Some eye ointments blur vision for a while, so night is the least disruptive time. The label or pharmacist will explain if a specific reason applies.
Sample lines with QHS, read in plain words
| Order | Plain meaning |
|---|---|
| Atorvastatin 40 mg PO QHS | One tablet by mouth every night at bedtime |
| Latanoprost 1 gtt OU QHS | One drop in each eye every night at bedtime |
| Latanoprost 1 gtt OS QHS | One drop in the left eye only, every night |
| Melatonin 3 mg PO QHS PRN sleep | By mouth at bedtime, only on nights it is needed |
The eye drop lines show why every letter matters: OU means both eyes and OS means left eye. Those eye abbreviations have their own error-prone history. These lines show format only.
Mixed case Qhs and the qhr problem
When the letters mix cases, as in Qhs with a capital Q and lowercase hs, the s can look like an r, and qhr means every hour. Reading a nightly sleep medicine as hourly would be a serious overdose. That is why the ISMP error-prone list names Qhs, along with qn for nightly, which has been mistaken for qh. ISMP recommends writing QHS in all capitals or qhs in all lowercase.
Pharmacy check: A technician enters a handwritten script for a sedating medicine that seems to say "qhr." The pharmacist flags it, since hourly dosing makes no sense for that drug, and the prescriber confirms the intent was every night at bedtime.
Electronic orders reduce the risk, but bedtime shorthand still shows up in faxes, handwritten notes and verbal habits. Keeping all three letters in one case, or writing nightly at bedtime, removes the doubt.
QHS compared with HS, QAM and daily
| Term | Meaning |
|---|---|
| HS | At bedtime; also half-strength, so ISMP points prescribers to QHS for bedtime |
| QHS | Every night at bedtime |
| QAM | Every morning |
| Daily | Once a day, time not fixed |
| QPM | Every evening |
QPM and QHS can land at similar hours, but QPM is tied to the evening and QHS to going to sleep. For a person who works nights, bedtime may be in the morning, and the dose follows their sleep. The prescription abbreviations section lists the rest of the timing family.
Every night medical abbreviation in nursing and pharmacy work
On the medication record, a QHS medicine appears once each day at the facility's bedtime hour. Nurses giving it check that the patient is ready for sleep and that any sedating medicines are not stacking up with others given in the evening. If a patient refuses or is asleep already, that is documented.
For pharmacy technicians, converting QHS into "every night at bedtime" or "nightly at bedtime" on labels is routine. Students practicing transcription should copy QHS exactly from the order and never shorten it to qh, which means every hour.
Questions about a nightly medicine
- Does it matter if I take it earlier in the evening on some nights?
- What if I wake up and realize I forgot it?
- Is it safe with alcohol or other sleep aids?
- If I work nights, should I take it at my bedtime or at night by the clock?
Answers to these depend on the specific medicine, so bring them to your pharmacist or prescriber. This page only explains what the abbreviation means.
Frequently asked questions
What does QHS mean on a prescription?
QHS means every night at bedtime. Pharmacy labels usually print nightly at bedtime or every night at bedtime.
What is the difference between HS and QHS?
HS means at bedtime, and QHS means every night at bedtime. Both describe a bedtime dose, but QHS makes the nightly repetition explicit, and HS has a second meaning, half-strength.
Is QHS an error-prone abbreviation?
No. ISMP recommends QHS or qhs for bedtime. The forms it lists as error-prone are mixed case Qhs, which can look like qhr, every hour, and qn, which can look like qh. Writing nightly at bedtime in words is also clear.
What does PO QHS mean?
PO QHS means by mouth every night at bedtime.
What does OU QHS mean on eye drops?
It means one dose in both eyes every night at bedtime. OU refers to both eyes, and many labels now write both eyes in words.