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

What does it mean when your healthcare provider prescribes medicine using terms such as QID or Q6H?

Do you need to wake up at night to take a dose if the drug is supposed to be taken every four to six hours? 

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

Although these terms may not be part of your usual lingo, knowing what they mean can help you figure out how to take your medicine correctly and safely.

Pharmacist talking to customer
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When to Take Your Medicine Dose

You may not know or recall when each drug dose should be taken. The patient handout you received from your healthcare provider or nurse may not be clearly written.

You don't want to bother your healthcare provider or anyone else and so you search for answers online.

While your online search may reveal when a drug dose is usually taken, talking with your healthcare provider or nurse is your best and safest option.

Your pharmacist is also a member of your health care team who is willing and able to help in this instance. They are experts when it comes to all facets of drugs and are keen to share their insight with you.

Your pharmacist can explain:

  • How the drug works
  • If it interacts with other drugs you take
  • Known side effects
  • When and how to take each drug dose

Your health care team is your top resource when it comes to questions about your medicines. Feel free to ask questions in person or give them a call when needed.


If you are in doubt about how and when to take your medicine, always ask your healthcare provider or pharmacist.

What Is QID vs. Q6H?

Your healthcare provider may prescribe your medicine for a set:

  • Time interval each day
  • Number of doses spread throughout the day

For instance, your healthcare provider may prescribe the drug QID or Q6H. What does this entail?

Q6H means you will need to take a dose every six hours around the clock. Setting your alarm can help you stick to this schedule whether you're asleep or awake.

QID means you will need to take a dose four times a day. The doses are usually spread out over waking hours but be sure to confirm this with your healthcare provider if it isn't spelled out.

Why Take Medicines Around the Clock?

Around-the-clock (ATC) medicines must be taken at set time intervals such as every six hours.

This may 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. Drugs used to treat heart disease and high blood pressure are good examples.

Thinking about how a drug works may help clarify why ATC schedules are needed.

Take blood thinners, for instance. You want to make sure drug levels in your bloodstream remain fairly constant over time.

If you don't keep to an ATC schedule but take a given number of doses at various times of the day instead, the levels of the drug in your blood will likely rise and fall instead of staying at a somewhat even level.

Pain that is severe may be better managed with ATC dosing of pain medicine. This is because this high level of pain tends to rebound quickly once the dose wears off.

Taking the right dose at set intervals prescribed by your healthcare provider may help improve and extend pain relief.


Taking medicine at set intervals around the clock as prescribed by your health care provider can keep the levels of the drug in your bloodstream at or above a target level. This can protect your health and keep symptoms in check for longer periods.

Why Take Medicines While Awake?

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 that means you need to take the drug only during wakeful hours.

Certain health issues are also more serious or severe than others. Your healthcare provider may instruct you to take medicine for strep throat four times a day while you're awake.

But if your illness course is more severe or places your health at great risk, ATC doses may be needed to make sure blood levels of the drug stay at target levels.

How Else Does Your Healthcare Provider Prescribe Drugs?

Below are other ways your healthcare provider may prescribe your medicines:

  • PO: Orally (per oral)
  • BID: Twice a day
  • TID: Three times a day
  • QID: Four times a day
  • QHS: Before bedtime or every hour of sleep
  • Q4H: Every 4 hours
  • Q6H: Every 6 hours
  • Q8H: Every 8 hours
  • PRN: As needed (usually for milder symptoms or ones that come and go)
  • AC or QAC: Before a meal. Your healthcare provider may also instruct that each dose be taken a certain amount of time before a meal. For instance, the drug may be best absorbed when taken on an empty stomach, so your healthcare provider may instruct you to take it one hour before eating.
  • PC: After a meal. Some drugs are absorbed better with a full stomach. But your healthcare provider may instruct you to take the dose after eating to decrease the risk of stomach upset.
  • IM: Intramuscular (into a muscle) injection
  • SubQ or SQ or SC: Subcutaneous (just under the skin) injection
  • IV: Intravenous (through an intravenous line or port)
  • QTT: Drops
  • OD: In the right eye
  • OS: In the left eye
  • OU: In both eyes

You may also 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 four pills.

Chances are you won't see all of these abbreviations in one script. Their use often depends on the type of drug and the reason why it's being prescribed.

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


Health care providers may prescribe your medicines using various shorthand terms. These describe how and when to take the drug and how it should be given or applied.

QD (once a day) and QOD (every other day) were banned by the Joint Commission in 2003 in order to prevent medication errors. The terms must be written out instead.

Preventing Medication Errors

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

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 health care 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 and Institute for Safe Medication Practices support this practice. They suggest which terms should be avoided and which ones need to be spelled out.

Although healthcare providers may be accustomed to using medical terms and abbreviations, it doesn't mean they have to. Many would be happy to avoid using these to safeguard your good health.


Health care providers often use shorthand terms when they prescribe a drug.

They may instruct you to take it PO BID, QAM and QPM. This may make little to no sense to you.

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

Be sure your provider clearly describes how, when, and where 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.

You can help prevent medication errors that place your health at risk by taking these actions.

If needed, ask your provider to spell out these and other terms that can cause medication mix-ups and mishaps to occur.

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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.
  1. Taddei S, Bruno RM, Ghiadoni L. The correct administration of antihypertensive drugs according to the principles of clinical pharmacology. Am J Cardiovasc Drugs. 2011;11(1):13-20. doi:10.2165/11586670-000000000-00000

  2. Crader MF, Arnold JK. Warfarin Drug Interactions. StatPearls Publishing.

  3. Thompson CA. JCAHO issues 'do-not-use' list of dangerous abbreviationsAm J Health Syst Pharm. 2003;60(24):2540–2542. doi:10.1093/ajhp/60.24.2540

  4. Tariq RA, Vashisht R, Sinha A, Scherbak Y. Medication dispensing errors and prevention. StatPearls [Internet]. https://www.ncbi.nlm.nih.gov/books/NBK519065/

  5. Institute for Safe Medication Practices. List of error-prone abbreviations. https://www.ismp.org/recommendations/error-prone-abbreviations-list

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