“Use as directed” can cause confusion for both patients and practitioners
August 25, 2016

Problem: If you are a pharmacist working in an outpatient setting, you have likely received a prescription in which the prescriber used the all-too-familiar sigs “use as directed” (UAD), “take as directed” (TUD), “as directed” (UD), or even the Latin “ut dictum” or “ut dict.” These sigs are ambiguous and do not provide adequate dosing instructions for patients to follow or for pharmacists to counsel the patient. They also make it difficult for hospital practitioners to know how the prescriber intended the medication to be used by the patient and to effectively conduct medication reconciliation or educate patients about drug therapy at discharge. “As directed” instructions invite misunderstandings about the dosing instructions, which have resulted in serious medication errors.

Although these sigs are archaic, some practitioners may believe the “as directed” phrases are only a problem if the directions for the medication can be variable or if the prescribed dose or frequency of use is outside recommended dosing parameters. However, pharmacists cannot assume that the prescriber has educated the patient about how to properly take the medication or that the patient will remember the instructions if provided. Explicit directions including the strength, dose, frequency of administration, route of administration, and duration of therapy (if appropriate) are needed in order for pharmacists to effectively educate patients and for patients to take their medications correctly. Furthermore, certain elements of a prescription (e.g., route, frequency, dosage form) may help pharmacists differentiate between two drug names that look or sound similar.

Several events reported to the ISMP National Medication Errors Reporting Program (ISMP MERP) illustrate errors that have occurred, at least in part, due to a prescription with some form of the “use as directed” phrase as the only dosing instructions provided. Some of these events involved high-alert medications, resulting in serious or potentially serious adverse outcomes for patients. 

Case examples

Case #1. An elderly man experienced a severe hypoglycemic event requiring hospitalization after the man’s son administered 100 units of NOVOLOG (insulin aspart) to his father. The insulin vial was labeled with the following directions: “Insulin aspart 100 units/mL. Give three times a day before meals as directed.” The son, who was the primary caretaker, had not been educated about insulin dosing when his father was discharged from a nursing facility the day before the event. He believed the 100 units/mL strength on the pharmacy label was the dose, given the lack of clarity with the “as directed” instructions.

Case #2. A mix-up occurred between CLINDESSE (clindamycin vaginal cream), used to treat bacterial vaginosis, and CLINDETS (clindamycin pledgets), used to treat acne. A prescriber left a message on a pharmacy’s voicemail system for a prescription for Clindesse, with instructions to “use as directed.” Upon playback, the order sounded like Clindets and was processed and dispensed as such. The error was discovered when the patient called the pharmacy to ask how to use the pledgets vaginally.

Case #3. Three errors involved mix-ups between the intended colonoscopy preparation drug VISICOL (sodium phosphate dibasic and sodium phosphate monobasic) and the opioid VICODIN (HYDROcodone and acetaminophen). In all three instances the prescription for Visicol was provided with “take as directed” instructions. Two of the errors resulted in severe harm after the patients took more than one-dozen Vicodin tablets over the course of a single day. (Note: The brand name product Visicol is no longer available.)

Case #4. An electronic prescription for EPIPEN (EPINEPHrine) was accidently transmitted to the pharmacy instead of the intended insulin pen needles. The EpiPen was dispensed to the patient’s wife with the instructions to “use as directed.” The pharmacist assumed that an EpiPen had been previously dispensed to the patient and did not provide counseling regarding its proper use. After experiencing difficulty while trying to connect the EpiPen to the insulin pen, the patient’s wife called the pharmacy and the error was discovered. 

Impact of “as directed” on inpatient care

Medication reconciliation. While the prescription sig “as directed” is most often seen with outpatient prescriptions, its use for dosing instructions can lead to medication errors during hospitalization related to medication reconciliation. The medication reconciliation process upon admission can be challenging under the best of circumstances. But if prescription labels on home medications include only “as directed” for the instructions, inpatient practitioners are faced with ambiguous, error-prone dosing information and must undertake the burdensome task of obtaining accurate information from the originating prescriber. Home medication lists that include “as directed” for the instructions do not provide the information necessary for accurate admission prescribing. The patient’s or caregiver’s account of how the medication was being used at home also may be inaccurate.   

Discharge education. Prescriptions provided to patients at discharge with instructions to take “as directed” provide no guidance for discharge education. As with the outpatient pharmacist, the hospital nurse or pharmacist may not know if or how the prescriber instructed the patient to take the medication. While patients may be asked to repeat the prescriber’s directions for use, leaving it up to the patient to remember what the prescriber said is not an acceptable solution. In fact, the “use as directed” instructions may discourage redundant education if practitioners are concerned about confusion they may cause by providing directions that differ with what the patient has been told.    

Frequency of “as directed” prescriptions

Survey. To learn more about the frequency and use of “as directed” instructions on prescriptions, ISMP conducted an online survey of outpatient pharmacists between May 19 and June 19, 2016. The survey was promoted in both our Community/Ambulatory Care and Acute Care editions of the ISMP Medication Safety Alert! It included 6 questions, 2 of which were related to respondent demographics, and the remaining 4 questions were related to the prevalence of the sig “use as directed” on prescriptions, medications commonly prescribed with “use as directed” instructions, how these prescriptions are sent to the pharmacy, and how pharmacists address these prescriptions.

Results. Despite the wide uptake of electronic prescribing and insurance repayment penalties for discrepancies over the correct days’ supply (which cannot be verified with the instructions “use as directed”), the results of the survey indicate that many drugs are still prescribed and dispensed with the directions “use as directed.” A total of 434 participants responded to the survey, 92.4% of which indicated their country of practice is the US. More than half of participants (55.7%) said that 1 to 5% of all prescriptions they receive are written with a sig of “use as directed.” Less than 10% of participants indicated that they never receive prescriptions written with instructions to “use as directed.” Respondents reported that they receive prescriptions that include the sig “use as directed” electronically (84.4%), as handwritten prescriptions (74.6%), and as facsimile prescriptions (55.6%). 

Respondents indicated that they most frequently verify the directions with the prescriber (74.7%) when they receive prescriptions written as “use as directed.” However, many also noted that they provide the usual and customary directions for the medication if they exist (59.3%), or they simply place “use as directed” on the bottle (43%). Many respondents noted that they confirm the days’ supply or maximum daily dose with the prescriber for billing purposes. Respondents also identified medications for which they have received prescriptions with the directions “use as directed” (Table 1).
“Other medications” not specified in the table include: colonoscopy/ bowel preparations, diabetic testing supplies, ophthalmic products, and inhalers.

Safe Practice Recommendations: To better safeguard the correct and appropriate use of medications, ISMP and the National Coordinating Council for Medication Error Reporting and Prevention (NCC MERP) ( recommend that prescribers always include explicit directions for use on prescriptions. While prescribers should also instruct patients about the use of any medications they prescribe, specifying the instructions on the prescription reinforces the intended care plan and allows the pharmacist and other healthcare providers, including those providing discharge education, to review the same instructions with the patient. Clear and complete instructions on prescriptions and prescription drug labels are also important to support accurate medication reconciliation during hospitalization.

If a prescription includes the sig “use as directed,” the outpatient pharmacist should clarify the directions for use with the prescriber and include those directions on the pharmacy label. For prepackaged items with directions on the package (e.g., Zithromax Z-Pak), some pharmacies use a sig code to print the standard directions on the label. If the directions exceed space limitations, a supplemental or overflow label may be required. When changes in the directions for use with medications such as insulin or warfarin have been communicated to the patient by the prescriber, there is an opportunity for the pharmacist’s involvement. When the initial prescription is filled for any medication that often involves frequent dose changes, pharmacists should encourage patients to notify the pharmacy of any dose changes they may receive from the prescriber’s office and discuss with the pharmacist how the leftover dosage form and strength can be used to fulfill the new dosing instructions until a new prescription is necessary. For drug doses that are based on home point-of-care testing, such as prandial insulin doses that may change with each meal, the directions for how to adjust the dose must be clear and explicit.

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