<h4>Purpose</h4>Best practices and guidance are provided for standardizing dosing instructions on prescription container labels of oral liquid medications by eliminating use of U.S. customary (household) units and adopting metric units universally, with the goal of decreasing the potential for error and improving safety and outcomes when patients and caregivers take and administer these medications.<h4>Summary</h4>Despite decades of best practice use of metric units in organized healthcare settings and advocacy by various professional societies, medication safety experts, and standards setting organizations, use of household units (e.g., teaspoon) on prescription container labeling instructions for oral liquid medications persists in community pharmacy settings. Five years after publication of the National Council for Prescription Drug Programs' (NCPDP's) original white paper advocating metric-only dosing, very few community pharmacy companies appear to require oral liquid dosing instructions be presented in metric-only units (mL). Error-prone dosing designations contribute to medication errors and patient harm. Use of both multiple volumetric units (e.g., teaspoonsful, tablespoonsful) and multiple abbreviations for the same volumetric units (e.g., mL, cc, mls; tsp, TSP, t) increases the likelihood of dosing errors. Opportunities for error exist with each administration of an oral liquid medication and, unless coordinated with dispensing of appropriate oral dosing devices and optimal counseling, can result in use of household utensils (e.g., uncalibrated teaspoons) or discordantly marked devices that can further exacerbate the risk of error. Since publication of NCPDP's original white paper, new standards have been adopted governing official liquid volume representation, calibrated dosing devices, and e-prescribing software which support the elimination of non-metric units to reduce use of dosing practices that are error-prone. In each case, U.S. customary (househol Abstract Purpose Best practices and guidance are provided for standardizing dosing instructions on prescription container labels of oral liquid medications by eliminating use of U.S. customary (household) units and adopting metric units universally, with the goal of decreasing the potential for error and improving safety and outcomes when patients and caregivers take and administer these medications. Conclusion Key factors contributing to dosing errors with oral liquid medications include use of multiple volumetric units and abbreviations; failure to institute policies and procedures that eliminate the use of non-metric (e.g., household) units and universally adopt metric-only dosing instructions in all settings; failure to coordinate dosing instructions with dosing device markings, appropriate type (oral syringe versus cup), and optimal volumes (e.g., 1-, 5-, or 10-mL devices); failure to adequately counsel patients about appropriate measurement and administration of oral liquid medication doses; and use or error-prone practices such as missing leading zeros and elimination of trailing zeros in prescriptions and container labels. • When the prescription Sig contains dosing designations in non-metric (e.g., U.S. customary or household units such as teaspoonful) or non-standard (e.g., dropperful) units, convert to only volumetric metric units (mL) for dosing instructions on the prescription container label. • When the prescription Sig contains dosing instructions in • When dispensing non-standardized concentrations of extemporaneously prepared formulations, it is critical that caregivers be instructed carefully about the volume to administer since it may differ from instructions they received with previous formulations of the oral liquid. They should be instructed to follow the current dosing instructions to avoid inadvertent underdosing or overdosing. • The standard abbreviation “mL” should be used on the prescription container label. Other abbreviations for milliliter (e.g., mls, cc) should not be used. For example, when the pharmacy receives a prescription with dosing in mL, staff may intentionally change it to teaspoon dosing or list both teaspoonful and mL (in parentheses) on the pharmacy label, believing most patients and caregivers are more familiar with household measures than metric dosing. However, adding such conversions between units increases the likelihood of a dispensing error. 33 ISMP recommends all electronic communication of medication information (e.g., EHR, e-prescribing) use metric-only units and USP abbreviations (e.g., mL; never cc or pluralized forms like mLs) and never use apothecary units or abbreviations (e.g., drams, minims, ounces) or household units (e.g., teaspoons, tablespoons). 48 AMA also recommends against the use of apothecary units and symbols. 76 4.1.5 Community pharmacy practices may decrease use of milliliter units Unfortunately, changes made in the volumetric units during community pharmacy dispensing may decrease the use of mL on the prescription container labeling. This consistency needs to extend to any oral instructions given to the patient at the time of prescribing and dispensing. Even when the prescription container label utilizes mL as the standard unit of measure and standard notation of decimal amounts in dosing designations, an oral dosing device with numeric graduations, metric-only units, and appropriate volume that corresponds to the container labeling should be made available and its use explained to the patient or caregiver so the dose can be correctly interpreted and measured. The goal of e-prescribing is to have an electronic prescription arrive at the pharmacy with complete and clear instructions, eliminating the need for the pharmacy staff to interpret a prescriber’s handwritten instructions and prevent transcribing errors. It has been shown to improve quality and safety by decreasing dispensing errors associated with handwritten prescriptions.