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

Deciphering Dosage Instructions and Timing

If your doctor has prescribed a medication using terminology such as QID or Q6H, what does that mean? If a medication is prescribed every four to six hours, do you need to awaken at night to take it? How can you interpret all of the other medical lingo describing your medication?

Let's translate what these terms mean so that you can take your medication the way that your physician—though speaking in what appears to be a foreign language—intended.

Pharmacist talking to customer
Terry Vine / Getty Images

Medication Timing on a Prescription

Many people have questions about timing when they get a prescription, look at orders on a discharge sheet, or remember instructions given in the office or hospital. You may hope to find the answers online so you don't need to call your physician to clarify her instructions.

While definitions of medication timing terms can help you take your medication the way it's intended, it is no substitute for talking directly with your physician. Your pharmacist is also an excellent resource when it comes to figuring out how your drugs work, their adverse effects, or how your drugs should be taken.

Pharmacists are knowledgeable and trained to answer all your questions. Patient education is a part of their training and a primary service they provide with each prescription. Don't hesitate to ask your questions in person or give your pharmacist a call to clarify instructions.

If you are in doubt about medication timing, always ask your doctor or pharmacist.

Differences Between QID and Q6H

One distinction in medication instructions is when a medication is prescribed at a specific time interval, or instead, is written as a number of doses to be taken daily.

An example would be a prescription that is prescribed QID (take the medication four times a day) and Q6H (take the medication every six hours). What is the difference? Here is the breakdown:

  • QID: When a medication is prescribed QID (four times a day) it is most often assumed that the medication will be taken four times a day spread out over waking hours. However, this is something to clarify with your physician or pharmacist if it isn't spelled out.
  • Q6H: A prescription prescribed q6h (every six hours) is usually designed to be taken every six hours, even if you have to set an alarm and wake up to make sure you follow this schedule.

Around-the-Clock Medications

Around-the-clock medications (ATC) are those which you need to take at a regular time interval, say every six hours. This may be needed to keep the levels of the drug in your bloodstream above a certain number.

If the amount of the drug in your bloodstream at any one time during a 24-hour day is important, taking a drug at a set interval is recommended.

A regular interval is often recommended with a high blood pressure medication, a heart disease medication, or something such as a blood thinner. To understand this, you may want to think about how the medication works.

With a blood thinner, for instance, you want to make sure your levels are relatively constant over time. With a QID schedule instead, you'd be apt to have leveled a bit higher than normal at some times and lower than normal at others.

ATC dosing is used for medications such as heart medications but may be used for pain medications as well, especially when getting behind on the medications may cause a rebound of pain symptoms.

With severe pain, and especially with pain medications used at the end of life, pain medications will be recommended ATC instead of PRN (as needed) to maintain better pain relief.

Waking Hours Medications

In contrast, if you are using a medication for mild pain or itching, using it during waking hours may be the best option if you don't need the medication in your system while you are asleep.

Some physicians clarify this on a prescription, for example writing either "QID while awake" or "q6h (or other timing) while awake."

The severity of the need for the medication may also determine the timing. For an infection such as a strep throat, medication may be prescribed four times daily while awake.

For a life-threatening infection, in contrast, it's important to take medication at set intervals (for example, every four hours) to make sure your blood levels of the drug are never below therapeutic levels.

Notations Found on Prescriptions

Here are the translations of other notations doctors use when writing prescriptions:

  • PO: Orally (per oral)
  • BID: Twice a day
  • TID: Three times a day
  • QID: Four times a day
  • QHS: Before bed
  • Q4H: Every 4 hours
  • Q6H: Every 6 hours
  • Q8H: Every 8 hours
  • PRN: As needed (PRN medications usually are needed only for minor symptoms, such as pain, nausea, or itching)
  • A.C. or q.a.c.: Before a meal. The prescription may include how long before a meal the medication needs to be taken, for example, one hour before eating (these are usually medications which need to be taken on an empty stomach for proper absorption so this description is important)
  • P.C.: After a meal. Some medications are absorbed better with a full stomach, though sometimes medications are recommended after a meal to decrease stomach upset
  • IM: Intramuscular (into a muscle) injection
  • Subq:Subcutaneous (just under the skin) injection)
  • IV: Intravenous (through an intravenous line or a port)
  • Q.T.T.: Drops
  • OD: In the right eye
  • OS: In the left eye
  • OU: In both eyes

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 four pills.

Obviously, you may not see all of these abbreviations in one script. For example, OD, OS, and OU are used only for eye drops and not for pills.

QD (once a day) and QOD (every other day) were banned by the Joint Commission on Accreditation of Health Organizations (JCAHO) in 2003 in order to prevent medications errors. The terms must be written out instead.

Preventing Medication Errors

The timing of doses isn't the only question people may have when it comes to deciphering prescriptions or oral communication from your doctor. Other abbreviations include the number of refills allowed and whether you are receiving a brand name or generic drug.

Medical errors are a significant cause of death in the United States. Fortunately, most of these errors are preventable when patients are active advocates for their health and ask plenty of questions.

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. 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. Updated July 5, 2019.

  3. Villars P, Dodd M, West C, et al. Differences in the prevalence and severity of side effects based on type of analgesic prescription in patients with chronic cancer painJ Pain Symptom Manage. 2007;33(1):67–77. doi:10.1016/j.jpainsymman.2006.07.011

  4. Brook I. Unexplained fever in young children: how to manage severe bacterial infectionBMJ. 2003;327(7423):1094–1097. doi:10.1136/bmj.327.7423.1094

  5. 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

  6. Anderson JG, Abrahamson K. Your Health Care May Kill You: Medical Errors. Stud Health Technol Inform. 2017;234:13-17.

Additional Reading