HS Meaning in Medical Prescription: Definition, Dose & Examples

In medical prescriptions, HS stands for Hora Somni, a Latin term meaning “at bedtime.” It tells you to take the medication right before going to sleep. This timing is often chosen for medicines that cause drowsiness or work best overnight.

How to read HS on a prescription

1. Locate the abbreviation — Find “HS” next to the dosage instructions.
2. Check the quantity — Example: “1 tablet HS” means one tablet at bedtime.
3. Note any extra instructions — Such as “with water” or “after food.”
4. Confirm with your pharmacist — Especially if you see similar terms like QHS.
5. Follow timing strictly — Changing it may reduce effectiveness or cause side effects.

HS vs. QHS vs. OD

Related: Meaning of OD, BD, TDS and SOS in a Doctor’s Prescription

When is HS dosing prescribed?

• Insomnia medications – To promote sleep.
• Anxiety or depression meds – To reduce daytime drowsiness.
• Allergy treatments – If they cause sedation.
• Pain relief – For overnight comfort.
• Seizure control – To prevent nighttime episodes.
• Acid reflux treatment – For overnight symptom control.

What happens if you don’t follow HS instructions?

Ignoring HS timing can reduce the drug’s effectiveness, increase side effects, or cause dangerous interactions. Always follow the prescribed schedule unless your doctor advises otherwise.