Common Prescription Abbreviations and Meanings

Some abbreviations look very similar to each other. For example, HS means “half strength,” but “hs” means hora somni, or “at bedtime.” It’s important to note that each abbreviation depends on whether it’s upper-case or lower-case, as well as the context of the prescription.

When your doctor hands you a prescription, it may seem unreadable. But knowing what the abbreviations mean is important – and may even save your life in case of an error. Here are some basic abbreviations to know before handing a prescription to a pharmacist.

• ā or ante - before
• alt - alternate
• amp - ampule
• amt - amount
• aq or h20 - water
• bol (bolus) - ball
• c̄ (cum) - with
• daw - dispense as written
• d/c - discontinue or discharge
• hr - hour
• liq - liquid
• Hx - history of
• OTC - over the counter
• p̄ (post) - after
• per - through or by
• q (quaque) - every
• rep - repeats
• Rx - prescription or treatment
• s̅ (sine) - without
• sol (solutio) - solution mixture
• sos (si opus sit) - if necessary
• susp - suspension mixture
• Tx - treatment
• UD or ut. dict. (ut dictum) - as directed
• w - with
• w/o - without
• x - multiplied by
• yo - years old

If a doctor wants you to take the medication in a particular way, that will be indicated in the subscription part of the prescription. It details which bodily route the patient will use for the medication and how the medication should be dispensed. Some examples include:

• AAA - apply to the affected area
• AD (auris dextra) - right ear
• AS (auris sinistra) - left ear
• cap - capsule
• comp - compound
• CD - controlled delivery
• CR - controlled release
• cr or crm - cream
• DR - delayed release
• emuls. - emulsion
• ER - extended release (or emergency room)
• HS - half strength
• gt (gutta) - drop
• inf - infusion
• IJ or (inj.) - injection
• iv (intravenous) - by vein
• IM - intramuscular
• IN or NAS - intranasal
• IR - immediate release
• MR - modified release
• nebul (nebula) - a spray
• npo (nil per os) - nothing by mouth
• OD (oculus dexter) - right eye
• OS (oculus sinister) - left eye
• OU (oculus uterque) - both eyes
• po (per os) - by mouth
• pr (per rectum) - by rectum
• SR - sustained release
• supp (suppositorium) - suppository
• syr (syrupus) - syrup
• tab (tabella) - tablet
• top (topical) - by skin
• TR - timed release
• ung (unguentum) - ointment
• vag - vaginally

One important detail to know is how often you need to take your prescription. You also need to know whether your prescription should be taken with food, with water, or by itself. Read these common abbreviations for how and how often a patient should take their medication.

• ac (ante cibum) - before meals
• achs (ante cibum et hora somni) - before meals and at bedtime
• ad lib (ad libitum) as you desire or need
• alt. h. (alternis horis) - every other hour
• ap (ante prandium) - before a meal
• atc - around the clock
• bid (bis in die) - twice a day
• cc (cum cibos) - with food
• dieb. alt. (diebus alternis) - every other day
• hs (hora somni) - at bedtime
• n or noct (nocte) - during the night
• noct. maneq. (nocte maneque) - at night and in the morning
• pc (post cibum) - after meals
• prn (pro re nata) - as needed
• qam (quaque ante meridiem) - every morning
• qd (quaque die) - once a day
• qid (quater in die) - four times a day
• qh (quaque hora) - hourly
• q.2h. - every 2 hours
• q.3h. - every 3 hours
• q.4h. - every 4 hours
• qn (quaque nocte) - every night
• qs (quantum satis) - as much as needed
• t.i.d. (ter in die) - 3 times a day

Knowing the potential side effects of a medication is important for patients. It can help them decide whether the benefits of taking the medication outweigh the risks. The following codes are used as warning about side effects, especially for people with certain medical conditions that may be affected by the medication.

• ASA - contains acetylsalicylic acid (aspirin)
• C - caution
• D - drowsiness
• G - glaucoma
• H - habit-forming
• I - interaction
• N/V or N&V - nausea and vomiting
• S - diabetes
• X SOS - contains a substance that could cause problems

A prescription contains handwritten instructions for the dispensing and administering of medications. It can be more than an order for drugs, as it can also include instructions for a therapist, the patient, nurse, caretaker, pharmacist or a lab technician for orders for lab tests, X-rays, and other assessments.

Prescriptions have five main sections:

• Superscription - This heading includes the date and the patient's name, address, age, and other important information.
• Symbol Rx - It’s the universal symbol for “prescription.”

• Inscription - This is the information about the medication itself. It has the name of the ingredients and the amount needed. It includes the main ingredient, anything that helps in the action of the drug, something to modify the effects of the main drug, and the vehicle which makes the medicine more pleasant to take.

• Subscription - The subscription section tells the pharmacist how to dispense the drug. This will have instructions on compounding the drug and the amount needed.

• Signature - The signature has the directions that are to be printed on the medicine. The word sig means “write on label."

Prescriptions vary from state to state and doctor to doctor. In some cases, doctors will use different terminology to describe what they want the pharmacist to do. For example:

• Sometimes the doctor will write “dispense as written," “do not substitute,” or “medically necessary."
• Sometimes the age of the child is required and often the doctor will put the condition that is being treated.
• Sometimes there is a label box. If the doctor checks this, the pharmacist labels the medicine; if not, the pharmacist only puts the instructions for taking it.

Historically, prescriptions were written in Latin and are still written that way today. But why would the medical industry rely on a language that is not commonly spoken today? There are two major reasons:

• Latin is more concise than other languages.
• Latin is a universally understood language among medical professionals. For instance, a doctor from France can write a Latin prescription that an American doctor can quickly understand.

The word prescription comes from the Latin word praescriptus. It has the prefix pre-, which means “before,” and the term script, which means “writing,” indicating that a prescription has to be written before a drug is compounded.

So where does the prescription symbol Rx come from? Some historians believe that its origin lies with ancient patients and doctors asking for protection from either the Eye of Horus or the Roman god Jupiter. Others believe that Rx is short for the Latin recipe, which means “to take.” Either way, Rx is a universal symbol to indicate a prescription.

If you have any doubts about the meaning of a prescription abbreviation, it is always advisable to consult with your doctor, pharmacist, or other medical professional. Only those within the medical field can truly decipher all of the different prescription abbreviations that show up in the industry.

If you’d like to learn more medical terminology, check out a list of medical abbreviations that you might read or hear from doctors and nurses. You can also read through definitions of common medical suffixes that can help you understand your diagnosis. And if you need a break from complex Latin vocabulary, read through some funny medical puns that are sure to tickle your funny bone!