Objective Parents administer oral medications with various measuring devices including metal teaspoons, calibrated spoons and oral syringes. We aimed to determine which was the most accurate.

Design Self-controlled, non-randomised, experimental study.

Setting Caregivers attending paediatric outpatient clinics.

Methodology Caregivers measured 5 ml of 120 mg/5 ml paracetamol suspension using a 5.0 ml metal teaspoon, 5.0 ml calibrated spoon and 5.0 ml oral syringe. Samples were weighed and converted to mls.

Main outcome measures The mean volume and variance of volumes were measured for each device.

Results We recruited 277 caregivers (98% parents). Volumes measured ranged from 0.83–6.52 ml. Accuracy did not vary with caregivers’ age, gender, instrument preference, number and age of children. The mean volumes measured with the oral syringe (95% CI 5.09 to 5.17 ml) and metal spoon (95% CI 3.90 to 4.08 ml) were significantly different to the desired 5 ml volume (p<0.0001), dissimilar to the mean volume measured using the calibrated spoon (95% CI 4.91 to 5.09 ml, p=0.99). The variance of volumes measured with the oral syringe (SD 0.348 ml) was significantly smaller (p<0.0001) than that measured using a calibrated spoon (SD 0.762 ml) or metal spoon (SD 0.749 ml).

Conclusions The calibrated spoon was the most accurate producing a mean volume of 5 ml, while the oral syringe had the smallest variance. The increased variability of calibrated or metal spoons may result in under or overdosing especially when administering drugs with a narrow therapeutic window. Health care professionals must make a case-by-case decision regarding which device is preferable depending on the medication in question. Parental education could improve measuring accuracy.