4 Times-a-Day (QID) or Every 6 Hours (Q6H) on a Prescription

QID and Q6H are medical abbreviations you might see on a drug prescription. Knowing what they mean can help you figure out how to take your medicine correctly and safely.

While the best place to get answers about your medications is usually your healthcare provider or pharmacist, they're not always available when questions arise—such as when you wonder whether you should get out of bed after four to six hours to stay on your dosing schedule.

This article covers common medical terms used to describe how and when to take your medicine.

Pharmacist talking to customer
Terry Vine / Getty Images

Questions for Your Pharmacist

  • How does the drug work?
  • How could it interacts with other drugs/supplements you take?
  • What are the known side effects?
  • When and how should you take each dose?

QID and Q6H

Your healthcare provider may prescribe your medicine to be taken:

  • A certain number of times per day
  • At certain intervals throughout the day

The medical community uses specific terms to convey these instructions. QID and Q6H are common ones.

QID: What It Means

This abbreviation may be written as QID, qid, or q.i.d. It's literal meaning is Latin: quater in die, which translates to "four times per day."

Usually, you can spread out the doses over your waking hours, so you don't need to get up overnight to take your medication. (It never hurts to double-check this with your healthcare provider or pharmacist.)

Why This Dosing Schedule Is Used

Certain doses of your medicine only need to be taken while you're awake. Your symptoms may be mild enough that you don't need a dose to hold you through the night.

In this case, your healthcare provider may prescribe the drug for "QID while awake" or something similar to clarify that you only need to take the drug during wakeful hours.

If your illness course is more severe or spreading out doses places your health at great risk, around-the-clock (ATC) doses may be needed to make sure the drug levels in your blood stay high enough.


The Latin meaning of Q6H (q6h, q.6h.) quaque 6 hora, or "every six hours." The six can be replaced with whatever number is appropriate to the prescription.

When your healthcare provider is this specific, it means you need to take your doses six hours apart, around the clock. So, at night, you should wake up six hours after taking your last dosage and have another one.

Why This Dosage Schedule Is Used

Taking medications ATC can help keep the levels of the drug in your bloodstream stable or above a target level.

Certain drugs work best when used at set intervals. Examples include drugs for heart disease and high blood pressure. The level of blood thinners (drugs that keep your blood from clotting) also need to be kept consistent.

If you only take these medications during wakeful hours, your blood level will likely rise and fall instead of staying at a somewhat even level.

Severe pain is often better managed with ATC dosing, as well. That's because pain tends to come back quickly once the dose wears off. Taking the right dose at set intervals may help keep your pain from spiking.

More Prescription Abbreviations

Your healthcare provider may use a variety of other abbreviations on your prescription, as well. (Again, these are for your pharmacist, and your provider and pharmacist should both go over instructions with you in plain English.)

PO per os Orally (by mouth)
BID bis in die Twice a day  
TID ter in die Three times a day  
QHS quaque hora somni  Every day at bedtime  
Q4H  quaque 4 hora Every 4 hours  
Q8H quaque 8 hora Every 8 hours  
PRN pro re nata As needed Usually for mild or intermittent symptoms
AC or QAC  ante cibum or quaque ante cibum Before a meal May be followed with a set amount of time before eating, such as one hour
PC post cibum After a meal  
IM Intramuscular (into the muscle) For injections only
SubQ, SQ, or SC Subcutaneous (under the skin) For injections only
IV Intravenous (in a vein) Given via an IV line or port
GTT gutta Drops For eye drops, ear drops, etc.
OD oculus dexter Right eye For drops or ointments
OS oculus sinister Left eye For drops or ointments
OU oculus uterque Both eyes For drops or ointments
Source: Pharmacy Times

The Joint Commission on Accreditation of Healthcare Organizations in 2003 banned the use of QD (once a day), QOD (every other day), and seven other abbreviations, saying they contributed to medication errors. Those terms must now be written out.

Preventing Medication Errors

Medication errors are a significant cause of death in the United States. The good news is most of these errors are preventable.

One way to do this is to advocate for your health. Keep asking questions until you get all the answers you need from your healthcare provider and/or members of your healthcare team.

Know what medicine is being prescribed along with how it's being prescribed and for what purpose. Make sure you understand exactly how and when to take your medicine. Other key things to know include the number of refills allowed and whether you are receiving a brand name or generic drug.

Don't be afraid to ask your healthcare provider to prescribe your medicine in terms you can clearly follow. Leading health organizations such as the Joint Commission on Accreditation of Healthcare Organizations and the Institute for Safe Medication Practices support this practice. They suggest which terms should be spelled out.

Although healthcare providers may be accustomed to using medical terms and abbreviations, it doesn't mean they have to. They should be open to using plain language to help you protect your health.


Healthcare providers often use shorthand terms when they prescribe a drug. They may use abbreviations on prescriptions such as QID and Q6H.

These and other forms of medical shorthand are well known in the healthcare setting. But using them is by no means a required practice.

Be sure your provider or pharmacist clearly describe how and when to take your medicine. Talk these over and ask them to clarify what you do not understand or would like to know about this drug. This can help prevent medication errors.

You can ask your provider to write prescriptions in plain English to help you understand them.

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5 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.
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