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Prescription Abbreviations

Understanding What Your Doctor Writes on a Prescription

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Updated April 08, 2014

Prescription Abbreviations

Prescription abbreviations are directions for your pharmacist.

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Doctors use prescription abbreviations (based on Latin words) that tell your pharmacist which medication to give you and directions on how to use that medication.

If you learn to understand the medical shorthand used by your doctor, you can read your own prescription immediately after it is written. This will help make sure that you know what medication you are getting and it will give you a chance to ask questions about your doctor's instructions.

Understanding Your Prescription May Help Prevent a Medical Error

The more you understand about your prescription, the less likely it is that you will have a medical error. For example, your pharmacist may make a mistake reading your doctor's handwriting. If your doctor's writing is not clear and easily read, your prescription may take longer to fill or you may be given the wrong dose or the wrong directions.

As a smart medical consumer, it is a good idea to check your prescription and make sure that it is filled correctly at the pharmacy. If you think there is an error or a discrepancy, you can alert the pharmacist or call your doctor.

Some doctor's offices now use electronic prescribing. You may receive a printed prescription to take to the pharmacy, or your prescription may be faxed or e-mailed to the pharmacy. Ask to see a printout of these prescriptions before leaving your doctor's office.

If you do not understand what your prescription says, do not be shy. Ask your doctor or another healthcare provider in the office for assistance. Your questions may help detect and prevent an error.

A Dr. Mike Quick Tip: Ask your doctor to write down on the prescription for what condition your medication is being used; e.g., not just "take once a day" but "take once a day for high cholesterol."

Generic vs. Brand Name

When writing a prescription, your doctor may use either the "generic" name of the medication or the "brand name". For example, sertraline is the "generic" name and Zoloft is the "brand name" used to identify a medication frequently prescribed for the treatment of depression.

In many states, pharmacists are allowed to dispense a generic medication, even if your doctor writes a prescription for the brand name version of the drug. However, if your doctor writes "DAW" (which means "dispense as written") or initials a box labeled "DAW" on your prescription, the pharmacist cannot legally substitute a generic medication for the brand name one.

Reading Your Prescription

Your prescription is usually written on a pre-printed pad with your doctor's name, address, and phone number. You may also see, either on the top or bottom of the prescription, special identification numbers, such as your doctor's Drug Enforcement Administration (DEA) number for narcotics or controlled substances.

Of course, there is space for your name and address, your age, the date, a place for your doctor's signature, and a blank area in which your doctor writes the following directions:

  • Name of the medication
  • Dose of the medication
  • How often to take the medication
  • When to take the medication
  • How to take the medication

Additionally, your doctor will indicate how much medicine the pharmacist should give you and the number of times that your prescription can be refilled.

Commonly Used Medical Abbreviations

Your doctor may use different abbreviations or symbols. If you do not understand them, ask your doctor or pharmacist for clarification.

How Often to Take Your Medication
ad lib - freely, as needed
bid - twice a day
prn - as needed
q - every
q3h - every 3 hours
q4h - every 4 hours
qd - every day
qid - four times a day
qod - every other day
tid - three times a day

When to Take Your Medication
ac - before meals
hs - at bedtime
int - between meals
pc - after meals

How Much Medication to Take
caps - capsule
gtt - drops
i, ii, iii, or iiii - the number of doses (1, 2, 3, or 4)
mg - milligrams
ml - milliliters
ss - one half
tabs - tablets
tbsp - tablespoon (15ml)
tsp - teaspoon (5ml)

How to Use Your Medication
ad - right ear
al - left ear
c or o - with
od - right eye
os - left eye
ou - both eyes
po - by mouth
s or ø - without
sl - sublingual
top - apply topically

Often the abbreviation "sig" will appear just before the directions on the prescription. "Sig" is short for the Latin, signetur, or "let it be labeled."

How to Read Your Doctor's Prescription - Some Examples

Example #1: Your diagnosis is high cholesterol

Zocor 10 mg.
This is the name of the medication and the dose.
Sig: i po qhs
Your instructions are to take 1 pill, by mouth, at bedtime.
Dispense #90
You will be given 90 pills, enough for about 3 months.
Refill 0 times
Your doctor has indicated no refills, most likely because she would like to check your blood cholesterol and then decide if you need more medication or a different dose.
DAW left blank
Your pharmacist will most likely give you simvastatin, the generic version of Zocor.

Example #2: Your diagnosis is type 2 diabetes

Glucophage 500 mg.
This is the name of the medication and the dose.
Sig: i po bid pc
Your instructions are to take 1 pill, by mouth, twice each day, after meals - this means that you should take this medication right after breakfast and right after dinner.
Dispense #90
You will be given 90 pills, enough for about 3 months.
Refill 3 times
Your doctor has indicated 3 refills, enough medication for one year. This may mean that your diabetes is "stable" and well controlled on this medication.
DAW left blank
Your pharmacist will most likely give you metformin, the generic version of Glucophage.

Example #3: Your diagnosis is high blood pressure

Diovan 40 mg.
This is the name of the medication and the dose.
Sig: i po qd
Your instructions are to take 1 pill, by mouth, once each day - you most likely can take this medication either before or after a meal since your doctor did not say otherwise.
Dispense #90
You will be given 90 pills, enough for about 3 months.
Refill 0 times
Your doctor has indicated no refills, most likely because she would like to check your blood pressure and then decide if you need more medication or a different dose.
DAW left blank
Your pharmacist will give you Diovan since there is no generic available for this drug.

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