Doctor Prescription Abbreviations Chart (OD, BD, TDS, QID, SOS, AC, PC, HS) — Complete Patient Decoder
Complete patient and pharmacist decoder for handwritten doctor prescription abbreviations: OD, BD/BID, TDS/TID, QID, SOS/PRN, AC/BBF, PC, HS, STAT, and...
Doctors and hospital outpatient departments use Latin shorthand ('Sig' or Signatura codes) and numerical circle grids (such as 1–0–1 or 1–1–1) to specify medication frequency, meal timing, and route of administration. Understanding the exact hour interval behind OD (Once Daily / q24h), BD or BID (Twice Daily / q12h), TDS or TID (Three Times Daily / q8h), QID (Four Times Daily / q6h), SOS or PRN (As Needed), AC/BBF (30–60 mins Before Food), PC (After Food), and HS (At Bedtime) prevents dangerous overdose and treatment failure.
1. Complete Frequency Decoder: OD, BD (BID), TDS (TID), QID, QOD & STAT
Every frequency abbreviation on an Indian or international prescription derives from classical Latin medical notation and maps to a specific hourly pharmacokinetic interval: (1) OD (Omne in Die) — Once Daily (Every 24 Hours). Represented in numerical Indian shorthand as 1–0–0 (Morning) or 0–0–1 (Night). Must be taken at the same clock hour every day. (2) BD or BID (Bis in Die) — Twice Daily (Every 12 Hours). Represented as 1–0–1. For optimal plasma steady-state concentration, space doses 12 hours apart (such as 08:00 AM and 08:00 PM). (3) TDS or TID (Ter in Die / Ter Die Sumendum) — Three Times Daily (Every 8 Hours). Represented as 1–1–1. Essential for time-dependent beta-lactam antibiotics (Amoxicillin) so serum concentrations remain above the bacterial Minimum Inhibitory Concentration around the clock (e.g., 07:00 AM, 03:00 PM, 11:00 PM). (4) QID (Quater in Die) — Four Times Daily (Every 6 Hours). Represented as 1–1–1–1 (06:00 AM, 12:00 PM, 06:00 PM, 12:00 AM). (5) QOD or Alt Day (Quaque Altera Die) — Every Other Day (48-hour interval, such as Monday, Wednesday, Friday). (6) STAT (Statim) — Immediately as an urgent single loading dose.
2. Meal Relationship & Circadian Codes: AC (BBF), PC, HS & SOS (PRN)
Food and gastric pH profoundly alter drug dissolution and mucosal irritation. Prescribers pair frequency codes with four crucial timing modifiers: (1) AC (Ante Cibum) or BBF (Before Breakfast): Take on an empty stomach 30 to 60 minutes before eating. This is mandatory for Proton Pump Inhibitors (Pantoprazole, Rabeprazole, Omeprazole—which require 30–45 minutes before breakfast so the drug is absorbed into parietal cell canaliculi just as meal-stimulated proton pumps activate), Levothyroxine (60 minutes before breakfast), and oral Bisphosphonates. (2) PC (Post Cibum) or After Food: Take within 15 to 30 minutes after finishing a meal. Mandatory for NSAID painkillers (Ibuprofen, Aceclofenac, Diclofenac, Naproxen), Metformin, Oral Corticosteroids (Prednisolone), and Amoxicillin-Clavulanate to buffer gastric acid and prevent erosive gastritis or nausea. (3) HS (Hora Somni) or At Bedtime: Take 30 minutes before going to sleep (typically 10:00 PM). Used for sedating antihistamines (Levocetirizine, Hydroxyzine), Montelukast, and short-acting statins. (4) SOS (Si Opus Sit) or PRN (Pro Re Nata): Take ONLY when required for an acute symptom (such as fever >100.4°F, migraine, or acute nausea). Never take SOS medications on a routine daily schedule once the symptom resolves.
3. Decoding Indian Numerical Dash & Circle Notation (1–0–1, 0–1–0, ½–0–½)
Across outpatient clinics and Jan Aushadhi slips in India, physicians and dispensing pharmacists frequently write a three-part or four-part numerical sequence separated by hyphens: Morning – Afternoon – Night (or Morning – Afternoon – Evening – Bedtime). A '1–0–1' code means 1 tablet in the morning, 0 in the afternoon, and 1 tablet at night (equivalent to BD / Twice Daily). A '1–0–0 (BBF)' code means 1 capsule before breakfast only. A '0–1–0 (PC)' code means 1 tablet after lunch—commonly used for daily Calcium + Vitamin D3 supplementation so it does not interfere with morning thyroid or iron tablets. When dots or circles are drawn on the back of a blister strip (e.g., O — X — O), the circles indicate the times of day to take the tablet.
4. ISMP Error-Prone Abbreviations & The Zero-Guessing Clinical Safety Rule
The Institute for Safe Medication Practices (ISMP) maintains a mandatory 'Do Not Use' list of handwritten abbreviations responsible for fatal 10-fold dosing errors: (a) Bare 'U' for Units (e.g., writing '4U' of Insulin can be misread as '40' or '44' units, causing fatal hypoglycemia; always spell out 'units'). (b) Trailing Zeros (e.g., writing '1.0 mg' where the decimal point is missed and read as '10 mg'; never use a trailing zero after a decimal point). (c) Lack of Leading Zeros (e.g., writing '.5 mg' instead of '0.5 mg', which is misread as '5 mg'; always place a leading zero before a decimal fraction). (d) 'QD' and 'QOD' (handwritten QD or QOD with a trailing period is frequently misread as QID—four times daily instead of once daily). MediMatch AI's Prescription Safety Engine automatically normalizes all ISMP error-prone notations and enforces the Zero-Guessing Rule—flagging any low-confidence or illegible handwritten token as NEEDS_REVIEW for mandatory human pharmacist verification.
5. Try the Interactive Instant Sig Decoder & AI Prescription Scanner
You can decode any prescription abbreviation and calculate standardized clock schedules immediately using the interactive Clinical Sig Decoder & Dosage Schedule Calculator on our homepage and Health Tools hub, or upload a photo of your prescription to the MediMatch AI Prescription Reader for automated Indian Pharmacopoeia salt verification, LASA safety checks, and one-click family pill reminders. Every scanned prescription undergoes per-field confidence scoring across drug name, dosage strength, dosage form, frequency, and duration, ensuring that high-alert medications (such as insulins, oral anticoagulants, opioids, concentrated electrolytes, and pediatric weight-based suspensions) are always routed through a human pharmacist verification checklist prior to administration.
Top 8 Essential Indian Medicines: Branded MRP vs. Jan Aushadhi Generic Comparison
Compare average Indian retail MRP of top branded formulations against government-certified PMBJP Jan Aushadhi bioequivalent generic prices and active salts. Verified against official PMBJP formularies, NPPA price caps, and CDSCO regulatory registries.
| Brand Name | Leading Manufacturer | Active Salt Formulation (IP) | Branded MRP | Jan Aushadhi Price | Savings % |
|---|---|---|---|---|---|
| Augmentin 625 Duo | GlaxoSmithKline Pharmaceuticals | Amoxicillin Trihydrate 500mg + Potassium Clavulanate 125mg IP | ₹220.00 | ₹58.00 | 74% |
| Dolo 650 | Micro Labs Ltd | Paracetamol (Acetaminophen) 650mg IP | ₹34.00 | ₹5.50 | 84% |
| Pantocid 40 | Sun Pharmaceutical Industries | Pantoprazole Sodium 40mg IP (Gastro-resistant) | ₹155.00 | ₹8.00 | 95% |
| Azithral 500 | Alembic Pharmaceuticals | Azithromycin Dihydrate 500mg IP | ₹132.00 | ₹24.00 | 82% |
| Glycomet 500 | USV Private Limited | Metformin Hydrochloride 500mg IP | ₹24.00 | ₹4.50 | 81% |
| Shelcal 500 | Torrent Pharmaceuticals | Elemental Calcium 500mg + Cholecalciferol (Vit D3) 250 IU IP | ₹134.00 | ₹16.00 | 88% |
| Telma 40 | Glenmark Pharmaceuticals | Telmisartan 40mg IP | ₹92.00 | ₹7.50 | 92% |
| Montair-LC | Cipla Ltd | Montelukast Sodium 10mg + Levocetirizine Dihydrochloride 5mg IP | ₹210.00 | ₹18.00 | 91% |
| Combined 8-Drug Essential Therapy Basket Total: | ₹1,001.00 | ₹141.00 | 85.9% Net Savings | ||
Frequently Asked Questions (Clinical & Regulatory)
Q1: What is the difference between BD and TDS on a doctor's prescription?
BD (Bis in Die) means Twice Daily—taking one dose every 12 hours (1–0–1, such as 8:00 AM and 8:00 PM). TDS (Ter in Die) means Three Times Daily—taking one dose every 8 hours (1–1–1, such as 7:00 AM, 3:00 PM, and 11:00 PM).
Q2: What does SOS mean on a medicine strip or prescription?
SOS (Latin: Si Opus Sit) means 'If Needed' or 'When Required' for an acute symptom like fever, pain, or acidity. Unlike antibiotic courses that must be taken on a fixed clock schedule until finished, SOS medicines should only be taken when the symptom is present, respecting the minimum 4-to-6-hour safety gap between doses.
Q3: Does AC mean before food or after food?
AC stands for Ante Cibum, which means BEFORE food (typically 30 to 60 minutes before a meal on an empty stomach). PC stands for Post Cibum, which means AFTER food (15 to 30 minutes after eating).
Q4: What are ISMP 'Do Not Use' dangerous medical abbreviations and why are they prohibited?
The Institute for Safe Medication Practices (ISMP) prohibits notations such as 'U' (misread as '0'), 'QD' (misread as 'QID'), and trailing zeros ('5.0 mg' misread as '50 mg') because they have directly caused catastrophic dosing errors.
Q5: What do the Latin prescription abbreviations 'OD', 'BD', 'TDS', and 'SOS' mean?
These standardized medical sig codes denote administration frequencies: 'OD' = Once Daily (Omne in Die), 'BD' = Twice Daily (Bis in Die), 'TDS' = Three Times Daily (Ter Die Sumendum), and 'SOS' = As Needed in Emergency (Si Opus Sit).
This clinical guide is authored and reviewed in accordance with the regulatory standards of the Indian Pharmacopoeia (IP), Central Drugs Standard Control Organization (CDSCO) drug schedules, and Pradhan Mantri Bhartiya Janaushadhi Pariyojana (PMBJP) bioequivalence guidelines. All therapeutic recommendations and drug interaction warnings are cross-referenced with official statutory publications.
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