When you first step into the world of pharmacy, everything feels new and a little overwhelming. Drug names, formulas, mechanisms… and then there are abbreviations. Tiny two-letter combinations that seem to carry a world of meaning. Ever looked at a prescription and felt like you were trying to crack a secret code?
You’re not alone.
Abbreviations are everywhere in the pharmacy world. They help save time, space, and effort in writing—but only if you understand them. Whether you’re studying for your exams or shadowing a pharmacist at the counter, knowing these abbreviations is absolutely essential.
So here’s a friendly guide to 10 of the most important abbreviations every pharmacy student should know—explained in simple, clear terms.
1. OD – Once a Day
Let’s start with one you’ll see almost daily—OD, which stands for “Omni Die” (Latin for “every day”). It simply means the medication should be taken once daily.
📌 Example: “Take 1 tablet OD after food.”
🧠 Quick Tip: OD is commonly used in general medicine. But in ophthalmology, it can also mean “right eye,” so always read it in context.
2. BD – Twice a Day
Next up, BD comes from “Bis in Die”, meaning twice daily. Typically, doses are spaced around 12 hours apart—once in the morning and once at night.
📌 Example: “Amoxicillin 500mg BD” = Take one tablet in the morning and one in the evening.
3. TDS – Three Times a Day
TDS, or “Ter in Die”, means three times a day. You’ll often see this for medicines that need to be taken every 8 hours.
📌 Example: “Paracetamol TDS” might be prescribed for managing fever or pain.
4. QID – Four Times a Day
When a medication needs to be given more frequently, you might come across QID – short for “Quarter in Die” (four times a day).
📌 Example: “Metronidazole QID” for an acute infection, taken about every 6 hours.
👀 Watch Out: With frequent dosing, timing and patient compliance become really important.
5. HS – At Bedtime
This one’s quite straightforward. HS means “Hora Somni”, or at bedtime.
📌 Example: “Cetirizine 10mg HS” is often taken at night to manage allergies—plus, it helps with sleepiness!
6. SOS – When Needed
SOS doesn’t mean emergency in the pharmacy world. It stands for “Si Opus Sit”, meaning if there is a need or as required.
📌 Example: “Tab Ibuprofen 400mg SOS for pain” – Take only when the pain becomes unbearable.
🧠 Reminder: Patients should be guided not to overuse SOS medications, especially painkillers or sleeping aids.
7. PO – By Mouth
PO, derived from “Per Os”, means by mouth or orally. It’s one of the most common administration routes for drugs.
📌 Example: “PO BD” = Take the medicine by mouth twice a day.
👂 Sounds simple but always check if the patient can tolerate oral meds (especially in hospital settings).
8. IV – Intravenous
No pharmacy education is complete without understanding IV, short for intravenous—directly into the vein.
📌 Used for: Quick absorption of drugs in emergencies or when oral route isn’t possible.
📌 Example: “Inj. Ceftriaxone 1g IV BD” means the drug should be injected into the vein, twice a day.
9. PRN – As Needed
Often confused with SOS, PRN comes from “Pro Re Nata” and also means as needed—but it’s usually used for regular medications that aren’t taken on a strict schedule.
📌 Example: “Inhaler Salbutamol PRN” for asthma – Use only during wheezing or shortness of breath.
📌 Note: Unlike SOS (used in emergencies), PRN can be part of a longer-term prescription plan.
10. SC – Subcutaneous
Last but not least, SC stands for subcutaneous, meaning the drug is injected under the skin (but not into muscle or vein).
📌 Example: Insulin injections are typically given SC before meals.
💉 Why it matters: The subcutaneous route offers slower, steady absorption—perfect for maintaining blood sugar levels in diabetic patients.
Why These Abbreviations Matter
You may wonder—why bother memorizing these short forms?
Here’s the thing: clear understanding = better practice. Misinterpreting even a single abbreviation could lead to a serious medication error. And in healthcare, there’s no room for guesswork.
As a pharmacy student, learning these terms early on will:
- Help you read and understand prescriptions quickly
- Improve your communication with doctors, nurses, and patients
- Make your case studies and viva exams smoother
- Build your confidence for internships or clinical practice