Physician's Prescription: 4 Times-a-Day (QID) or Every 6 Hours (Q6H)?

A Closer Look at Dosage Instructions


A question from a reader: When the dose of a medication is 4 times a day, does this mean 4 times over the 24 hours (that is, do I have to wake up in the middle of the night to take my medication) or 4 times over the "wake hours"?

An interesting question that I bet a lot of people think about when they get a prescription.

Without knowing the medication you are taking or the condition that is being treated, it is difficult for me to be precise.

However, it depends on how your physician wrote the prescription. If she wrote to take your medication "qid," then that means 4 times a day spread over the waking hours. If she wanted you to take the medication every six hours, then she would have written "q6h."

Your pharmacist interprets these notations and provides the directions on the bottle. If you need a more exact answer, speak with your pharmacist; he knows how the medication should be used and what your physician ordered.

Other Notations Found on Prescriptions

Here are some other notations commonly found on prescriptions:

  • PO means orally
  • QD means once a day
  • BID means twice a day
  • QHS means before bed
  • Q4H means every 4 hours
  • QOD means every other day
  • PRN means as needed
  • a.c. means before a meal
  • p.c. means after a meal
  • IM means intramuscularly (injection)
  • Subq means subcutaneous (injection)
  • IV means intravenous (injection)
  • q.t.t. means drops
  • OD means in the right eye (think eye drops)
  • OS means in the left eye (think eye drops)
  • OU means in both eyes (think eye drops)

Additionally, you may see a symbol on your script that looks like a "T" with a dot at the top of it. This abbreviation means one pill. There may be one to 4 T's with dots at the top of them signifying one to 4 pills.

Obviously, you may not see all of these abbreviations on one script.

For example, OD, OS and OU are used only for drops and not for pills.

Please remember in addition to your physician, your pharmacist is an excellent resource when it comes to figuring out how your drugs work or their adverse effects as well as how your drugs should be taken. Pharmacists are knowledgeable and trained to answer all your questions. (Like physicians, pharmacists go to graduate school and many complete residencies.) Many people pass on asking their pharmacists questions, which is unfortunate because a pharmacist can be a very valuable resource. Thus, the next time you're at the pharmacy and have a question please feel free to ask your pharmacist.

More Information About Prescriptions:

Content edited by Naveed Saleh, MD, MS, on 1/20/2016.

Selected Sources

"Prescription Abbreviations" PDF document accessed from the University of Minnesota Duluth website on 1/20/2016.

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