OD, BD, TID, TDS, PC, AC, HS — What Do Doctor Prescription Codes Mean?
By Aswini Medicals · August 5, 2025 · 5 min read
Quick Decoder
OD = Once Daily
BD / BID = Twice Daily
TID / TDS = Three Times Daily
QID = Four Times Daily
PC = After Food
AC = Before Food
HS = At Bedtime
SOS = When Required
Doctor prescriptions use short Latin abbreviations that most patients have never been taught. "1 tab OD PC for 5 days" is clear to a pharmacist — but confusing to anyone else. This guide decodes every common prescription code so you know exactly when and how to take your medicine.
Frequency Codes — How Many Times Per Day
| Code | Full form | Meaning | Typical timing |
|---|---|---|---|
| OD | Omni die (once daily) | Once per day | Morning or night as advised |
| BD / BID | Bis die (twice daily) | Twice per day | Morning + Evening (every ~12 hours) |
| TID / TDS | Ter in die / Ter die sumendus | Three times per day | Morning + Afternoon + Evening (every ~8 hours) |
| QID / QDS | Quater in die (four times daily) | Four times per day | Every ~6 hours (e.g. 6am, 12pm, 6pm, 12am) |
| SOS / PRN | Si opus sit / Pro re nata | When required / as needed | Only when you have the symptom (pain, nausea, etc.) |
| OW | Once weekly | Once per week | Same day each week (e.g. some calcium or iron tablets) |
| OD HS | Once daily at bedtime | Once per day, at night | Just before sleeping |
TID vs TDS: These mean the same thing — three times daily. TID is more common in older prescriptions; TDS is common in UK-trained doctors' prescriptions. Both = 3 times per day.
Meal-Time Codes — Before or After Food
| Code | Full form | Meaning | Why it matters |
|---|---|---|---|
| PC | Post cibum | After food | Reduces stomach irritation (e.g. Ibuprofen, Metformin) |
| AC | Ante cibum | Before food | Better absorption (e.g. thyroid tablets, some antibiotics) |
| CC | Cum cibo | With food | Take at the same time as eating |
| HS | Hora somni | At bedtime | Sleeping aids, antacids, some cholesterol medicines |
| AF | After food | After food (same as PC) | English shorthand, same meaning as PC |
| BF | Before food | Before food (same as AC) | English shorthand, same meaning as AC |
Combination Codes — Frequency + Meal Time Together
Doctors often combine frequency and meal-time codes. Here are the most common combinations:
| Code | Meaning | Example |
|---|---|---|
| OD PC | Once daily, after food | 1 tablet in the morning after breakfast |
| OD AC | Once daily, before food | 1 tablet in the morning before breakfast (thyroid tablets) |
| OD HS | Once daily, at bedtime | 1 tablet at night before sleeping |
| ODPC | Once daily, after food (written together) | Same as OD PC |
| ODHS | Once daily, at bedtime (written together) | Same as OD HS |
| BD PC | Twice daily, after food | 1 tablet after breakfast + 1 tablet after dinner |
| TDS PC | Three times daily, after food | After breakfast, after lunch, after dinner |
| TDS AC | Three times daily, before food | Before breakfast, before lunch, before dinner |
| OD AF | Once daily, after food | Same as OD PC (AF = after food in English) |
| OD BLN | Once daily, at bedtime (at night) | At night before sleeping |
Duration Codes — How Many Days
| Code | Meaning | Example prescription |
|---|---|---|
| 3/7 | For 3 days | "1 tab BD 3/7" = twice daily for 3 days |
| 5/7 | For 5 days | "1 tab TDS 5/7" = 3 times daily for 5 days |
| 7/7 | For 7 days (1 week) | "1 tab OD 7/7" = once daily for one week |
| 2/52 | For 2 weeks (52 weeks in a year) | "1 tab BD 2/52" = twice daily for 2 weeks |
| 1/12 | For 1 month (12 months in a year) | "1 tab OD 1/12" = once daily for 1 month |
Other Common Prescription Abbreviations
| Code | Meaning |
|---|---|
| Tab | Tablet |
| Cap | Capsule |
| Syr | Syrup |
| Oint | Ointment |
| Gtt / Drops | Drops (eye, ear, or nose) |
| Stat | Immediately — take the first dose right now |
| TD | Twice daily (some doctors use this instead of BD) |
| ODA | Once daily (alternate shorthand) |
| Rx | Prescription (the ℞ symbol at the top of a prescription) |
| Mane | In the morning |
| Nocte | At night |
Reading a Full Prescription — Examples
1 Tab Amoxicillin 500mg TDS PC × 5/7
→ Take 1 Amoxicillin 500mg tablet, three times daily, after food, for 5 days
Timing: After breakfast + After lunch + After dinner, for 5 days
1 Tab Eltroxin 50mcg OD AC
→ Take 1 Eltroxin 50mcg tablet, once daily, before food
Timing: Every morning, 30 minutes before breakfast, on an empty stomach
1 Tab Metformin 500mg BD PC
→ Take 1 Metformin 500mg tablet, twice daily, after food
Timing: After breakfast + After dinner
1 Tab Atorvastatin 10mg OD HS
→ Take 1 Atorvastatin 10mg tablet, once daily, at bedtime
Timing: Every night just before sleeping
Tab Paracetamol 650mg SOS
→ Take 1 Paracetamol 650mg tablet when required (only if you have fever or pain)
Do not take it on a schedule — only when needed
Does OD Mean Morning or Night?
OD simply means once daily — it does not specify morning or night by itself. The doctor or pharmacist will usually advise when to take it based on the medicine:
- Morning — thyroid tablets (empty stomach), blood pressure medicines, most vitamins
- Night / bedtime — cholesterol medicines (statins work better at night), sleeping aids, certain antacids
- With food (morning or evening) — Metformin, Ibuprofen, most antibiotics
If your prescription says OD without specifying timing, ask your pharmacist — it takes 30 seconds and ensures you take it correctly.
Does BD Mean Before or After Food?
BD only means twice daily — it does not by itself say before or after food. That is what the PC, AC, or CC codes are for. So "1 tab BD PC" means twice daily after food, while "1 tab BD AC" means twice daily before food. If no meal-time code is written, the medicine can generally be taken either way — but ask your pharmacist if unsure.
💡 Can't Read Your Prescription?
Bring your prescription to Aswini Medicals and we will read it for you, explain every code, and dispense your medicines correctly. Call us at +91 99455 60605 — free prescription help, no charge.
Frequently Asked Questions
What does 1 tab OD mean in a prescription?
1 tablet, Once Daily — take one tablet per day. OD = omni die (Latin for "every day").
What does BD mean in a prescription?
Twice Daily. "1 tab BD for 5 days" = 1 tablet in the morning and 1 tablet in the evening, for 5 days.
What does TID or TDS mean in a prescription?
Both mean Three Times Daily — morning, afternoon, and evening (roughly every 8 hours). TID and TDS mean the same thing.
What does PC mean in a prescription?
After Food — from Latin "post cibum". Take the medicine after eating a meal.
What does AC mean in a prescription?
Before Food — from Latin "ante cibum". Take the medicine before eating.
What does HS mean in a prescription?
At Bedtime — from Latin "hora somni". Take the medicine just before sleeping.
What does ODPC mean in a prescription?
Once Daily After Food. OD + PC combined into one shorthand.
What does 5/7 mean in a prescription?
For 5 days. The "/7" means "out of 7 days in a week." So 5/7 = 5 days, 7/7 = 1 week, 2/52 = 2 weeks, 1/12 = 1 month.
What is the difference between OD, BD, TID, and QID?
OD = once daily. BD = twice daily. TID/TDS = three times daily. QID = four times daily.
Also read: How to Read a Doctor's Prescription · What to Do If You Miss a Dose · Medicines That Should Not Be Taken Together
Need help reading a prescription? Visit Aswini Medicals or call +91 99455 60605 — free advice →