Prescription Abbreviations Including Sig

In This Article

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.

Doctor writing a prescription
 Jupiterimages/Stockbyte/Getty Images

Prevent a Prescription 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.

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."

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.

Common Medical Abbreviations

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

Medical Abbreviations
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  
cap capsule
gtt drops
i, ii, iii, or iiii number of doses (1, 2, 3, or 4)
mg milligrams
mL milliliters
ss one-half
tab tablet
tbsp tablespoon (15 mL)
tsp teaspoon (5 mL)
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

DAW

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.

Sig

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."

Examples

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.

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 #180: You will be given 180 pills, enough for three months.
  • Refill 3 times: Your doctor has indicated three 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.

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 likely give you valsartan, the generic version of Diovan.
Was this page helpful?
Article Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Pharmacy Times. A Technician's Guide to Pharmacy Abbreviations.

  2. Fallaize R, Dovey G, Woolf S. Prescription legibility: bigger might actually be better. Postgrad Med J. 2018;94(1117):617-620. doi:10.1136/postgradmedj-2018-136010.

  3. Ross JS. Therapeutic Substitution-Should It Be Systematic or Automatic?. JAMA Intern Med. 2016;176(6):776. doi: 10.1001/jamainternmed.2016.2271

Additional Reading