Quantifying household liquid medicine dosing errors in Sri Lanka: A hidden public health risk

Inaccurate measurement of liquid medicines remains a critical yet underrecognized patient safety concern in low-resource settings. In Sri Lanka, despite the adoption of metric units in formal healthcare, the use of uncalibrated household items such as teaspoons and tablespoons remains widespread. Bulk dispensing without standardized measuring aids is common, and dosing instructions often rely on informal household measures. This study assessed the volume accuracy of commonly used household liquid medicine measuring tools in a Sri Lankan suburb, highlighting their potential contribution to dosing errors. A cross-sectional survey of 50 households in Karapitiya, Galle District, Sri Lanka, was conducted. Frequently used measuring devices were tested using validated weighing and volumetric methods. Accuracy was evaluated against United States Pharmacopoeial (USP) specifications for acceptable deviation limits. Only 53.4% of measuring cups met USP accuracy standards across all tested volumes, although 86.2% complied for the 5.00 mL mark. Meanwhile, 62.5% of graduated measuring spoons failed to meet the standard. Household teaspoons and tablespoons demonstrated substantial variability, with volumes ranging from 2.893-7.759 mL and 4.252-15.043 mL, respectively. Over 93% of both spoon types delivered less than their expected standard volumes. The study discloses widespread inaccuracy in common dosing tools used in Sri Lankan households, posing avoidable risks to medication safety. It calls for urgent regulatory action to mandate standardized, calibrated devices and integrate user education into prescribing and dispensing practices. These findings point out a critical safety gap in primary care, particularly in low- and middle-income settings.