Decoding Prescription Sig Codes: "Sig 2 Puff QID 30 Days" Explained
Prescription directions (Sig) use Latin abbreviations. "Sig 2 puff QID 30 days" translates to:
Take 2 puffs by inhalation four times daily for 30 days.
Breakdown
| Component | Abbreviation | Latin Origin | Meaning |
|---|
| Dose | 2 puff | — | Two actuations/inhalations |
| Frequency | QID | quater in die | Four times a day (~every 6 hours) |
| Duration | 30 days | — | Thirty-day supply |
Common Sig Abbreviations
- QD / qd / daily = once daily
- BID / bid = twice daily (bis in die)
- TID / tid = three times daily (ter in die)
- QID / qid = four times daily (quater in die)
- QHS / qhs = at bedtime (quaque hora somni)
- PRN / prn = as needed (pro re nata)
- AC / ac = before meals (ante cibum)
- PC / pc = after meals (post cibum)
- PO / po = by mouth (per os)
- SL / sl = sublingual
- IV / IV = intravenous
- IM / im = intramuscular
- SC / SQ / subq = subcutaneous
- INH / inh = inhalation
- TOP / top = topical
Safety Note
- The Joint Commission "Do Not Use" list: Avoid QD (use "daily"), QOD (use "every other day"), trailing zeros (1.0 mg), leading decimals (.5 mg → 0.5 mg), MS/MSO4/MgSO4 (write "morphine sulfate," "magnesium sulfate").
- E-prescribing and structured sig fields reduce ambiguity.
- Patients should receive plain-language labels: "Inhale 2 puffs 4 times a day for 30 days."
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