Demystifying Medical Prescriptions

 A few Quotes

“Doctors’ handwriting proves that medicine is indeed a mystery — from diagnosis to deciphering the script.”

“A doctor’s signature looks like an ECG report — irregular, fast, and impossible to interpret.”

“If pharmacists can read doctors’ handwriting, they deserve a Nobel Prize for cryptography.”

Doctor Captain

If your body is a little vessel tossing in the vast, fathomless ocean of life with dangerous diseases as killer sharks prowling to devour you, doctors are the trained and seasoned captains who save you from drowning or being devoured, as far as possible. They help you to stay afloat, and on course for your life-journey; even though you mostly ignore the captain’s counsel to eat sensibly, exercise regularly, keep your weight in check (your boat is not designed to carry a load beyond its capacity!), and avoid alcohol and smoking.

Whenever you consult a doctor, he never says, ‘You’re soon to drown, begin saying your prayers, and prepare for your final destination.’ Instead, he mutters inaudible soothing words, writes an indecipherable prescription, beams a friendly smile at you which means, ‘Consultation is over; time for the next patient, you know.’

You present the prescription at a medicine shop. The 10^th Fail who is the body-double for the pharmacist required by law to dispense medicine has no difficulty in deciphering the codes. Business teaches smart survival skills including decoding the illegible hand of any doctor! He brings out from an open almirah the relevant alphabetically indexed plastic box and fishes out the medicine that you need.

OD, BD, TDS???

You return home with the sachet of tablets and capsules; but then you hesitate to pop the pill wondering which one to take when and what quantity for how many days? The doctor may have given rapid-fire oral instructions which never registered since you were mentally calculating the per minute consultation fees charged by your eminent doctor. You peer at the holy codes - OD, BD, TDS, SoS, and similar mysterious jargon in the prescriptions.

What does it mean? OD is Once Daily; that’s an easy one? How about BD? Twice Daily, you know; but why not call it TD? Okay, coz TDS means Thrice Daily; but what’s the ‘S’ for, you wonder. You may also wonder if many doctors are themselves aware of the origin of these mysterious notations.

Greek or Latin?

Is that Greek and Latin for you? Well; OD, BD, and TDS in medical prescriptions originate from Latin, not modern English. Modern medicine mostly refers to the western, allopathic system and its practitioners take the Hippocratic Oath. Hippocrates was a Greek medicine man. Why then do doctors follow the Latin notations and not Greek? Because, from Renaissance onwards, Latin had become the language of all learning including medicine.  

In due course, Latin terms like:

• Omni die (OD) – once a day
• Bis die (BD) – twice a day
• Ter die sumendum (TDS) – thrice a day
• Si opus sit (SOS) – if necessary

became standard medical shorthand worldwide — through colonial education and global standardization.

(Don’t  fear the ‘die’  in OD, BD, and TDS; it’s Latin for ‘day’ not ‘death.’ The Latin word for death is  “mŏrs” derived from the Proto-Indo-European root mr̥tós, which means “mortal” or “dead.” This root is related to various terms in other Indo-European languages, such as “mortality” in English, and “mort” in French. The words Sanskrit mṛtyu (मृत्यु) and Latin mors are etymologically related (cognates).)

But why do doctors persist with these Latin terms? Why in India where millions of patients have no knowledge even of English, not to speak of Latin?

Simple Symbols

To be fair to doctors, many use easy-to-understand, simple symbols – 0 for OD, 0-0 for BD, 0-0-0 for TDs. How many days? No issue; 0-0-0 x 7. Even illiterate patients would get it. Anyway, after so much investment in school education and adult literacy; someone in the family would understand what the doctor has prescribed!

AI gives up

Hoping that AI might be of help, I uploaded a recent prescription by a doctor with a memorable name: Darwin Thakur. Gemini AI read the prescription with much diligence and patience, and made several intelligent guesses about the medicines prescribed, but conceded defeat, and said, "Sorry, I can't read the handwritten prescription with accuracy, and I advise you against taking any medication based on my partial reading. I suggest you call up the doctor's office and seek the clarifications you need."

Tutorial for Doc

Next time your doctor writes a prescription for you, why don’t you politely ask for the origin and history of OD, BD, and TDS? If he falters, you could give a brief tutorial, and demand a reasonable discount in the Consultation Fees!

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High Court's directives on legible prescriptions

In a landmark ruling, the Punjab and Haryana High Court has mandated clear and legible prescriptions; and a set of directions has been issued by Justice J. S. Puri on August 27, 2025.

In an anticipatory bail application  in a criminal case, the judge noticed that the Medico-Legal Report (MLR) submitted by a doctor was completely illegible, which led the court to take suo motu cognizance of the systemic issue.

The directives hold that the "Right to legible medical prescription and diagnosis" is an integral part of the Right to Health, which is a Fundamental Right under Article 21 of the Constitution of India.

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Postscript

Why is the doc’s prescription illegible?

A doc is a detective. He launches a quick investigation, identifies the potential culprits, and orders immediate preventive or deterrent action on those villains. He has the unenviable task of completing this complex, challenging task in five minutes or less – the typical time spent by a specialist doc per patient. Obviously, he has no time to write an elaborate prescription like the following:

1.   Tab X – 1 Tab after lunch & 1 after dinner for 7 days

2.   Cap Y – 1 Cap 3 times a day for 4 days

3.   Tab Z – 2 Tabs daily for 30 days (A nutraceutical -  possibly curcumin, a fancy name for haldi – costing 120 rupees a Tab!)

4.   Tab ZZ – Analgesic – SoS

That’s why he scribbles fast. He knows well that the chemist across the street would easily decipher the codes which constitute the mysterious lingua franca of the medical care community.

What’s Rx?

A reader queried – what’s Rx? I had no idea, and looked up. That, too, is Latin; an abbreviation for ‘Recipe.’ The doc isn’t asking you to cook, but to eat the fistful of medicines he has listed in the menu.

I asked ChatGPT to provide a list of other common abbreviations used by docs. Here is the list:

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Common Abbreviations Used in Medical Prescriptions

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1. Frequency of Dosage

Abbreviation	Latin Term	Meaning / Explanation
OD	Omni die	Once daily
BD	Bis die	Twice daily (morning and evening)
TDS / TID	Ter die sumendum	Thrice daily (morning, afternoon, night)
QID	Quater in die	Four times a day (every 6 hours)
HS	Hora somni	At bedtime (night)
SOS	Si opus sit	As needed (only when required)
STAT	Statim	Immediately
Q4H / Q6H / Q8H	Quaque 4/6/8 hora	Every 4, 6, or 8 hours
QOD	Quaque altera die	Every other day

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2. Timing in Relation to Meals

Abbreviation	Latin Term	Meaning / Explanation
AC	Ante cibum	Before meals
PC	Post cibum	After meals
HS	Hora somni	At bedtime
PRN	Pro re nata	As needed
CC	Cum cibum	With food
BID AC / BID PC		Twice daily before / after meals

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3. Route or Method of Administration

Abbreviation	Latin Term / Modern	Meaning / Explanation
PO	Per os	By mouth (oral)
IM	Intra muscularis	Intramuscular injection
IV	Intra venous	Intravenous injection
SC / Subcut	Sub cutis	Subcutaneous (under the skin)
SL	Sub lingua	Under the tongue
INH	—	Inhalation
TOP / APPL.	—	Topical (apply on skin)
PR	Per rectum	Rectally
PV	Per vaginam	Vaginally
OTC	—	Over-the-counter (no prescription needed)

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4. Duration, Quantity, and Course

Abbreviation	Meaning / Explanation
X 5 days	Continue for 5 days
Tab / Cap / Syr	Tablet / Capsule / Syrup
Inj.	Injection
Gtt.	Drops (for eyes, ears, or nose)
Ung. / Oint. / Cream	Ointment
Supp.	Suppository
Neb.	Nebulization
NR	No refill (do not repeat without advice)
Refill x1	May be refilled once

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5. Miscellaneous and Cautionary Terms

Abbreviation	Meaning / Explanation
Rx	Recipe – “Take thou” (beginning of prescription)
Dx	Diagnosis
Tx	Treatment
Px	Prognosis
Hx	History
R / L / B/L	Right / Left / Bilateral
NPO	Nil per os – Nothing by mouth (fasting)
BM / BP / HR / PR	Bowel movement / Blood pressure / Heart rate / Pulse rate
NKDA	No known drug allergy

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Note

Most abbreviations derive from Latin — a legacy of early European medical education.
Modern safety guidelines (WHO, NMC, FDA) recommend writing full English terms such as “once daily” or “after meals” to reduce errors and make prescriptions clearer for patients.

 

(Image by Gemini AI)