diff --git a/src/main/java/org/snomed/cdsservice/service/medication/dose/SnomedMedicationDefinedDailyDoseService.java b/src/main/java/org/snomed/cdsservice/service/medication/dose/SnomedMedicationDefinedDailyDoseService.java
index ddae798..e40973d 100644
--- a/src/main/java/org/snomed/cdsservice/service/medication/dose/SnomedMedicationDefinedDailyDoseService.java
+++ b/src/main/java/org/snomed/cdsservice/service/medication/dose/SnomedMedicationDefinedDailyDoseService.java
@@ -287,13 +287,13 @@ private void aggregateMedicationsBySubstance(Map<String, AggregatedMedicationsBy
             try {
                 prescribedDailyDoseInUnitOfSubstanceStrength = getPrescribedDailyDoseInUnitOfSubstanceStrength(prescribedDailyDose, strengthValue, strengthUnit, denominatorValue, denominatorUnit);
             } catch (Exception e) {
-                throw new ResponseStatusException(HttpStatus.PRECONDITION_FAILED, String.format("Mismatched Dose units for the medicine %s", snomedMedicationLabel), null);
+                throw new ResponseStatusException(HttpStatus.PRECONDITION_FAILED, String.format("Prescribed dosage could not be validated for %s. Reason: Invalid dose unit.", snomedMedicationLabel), null);
             }
             PrescribedDailyDose prescribedDailyDoseInUnitOfDDD;
             try {
                 prescribedDailyDoseInUnitOfDDD = getPrescribedDailyDoseInUnitOfDDD(prescribedDailyDoseInUnitOfSubstanceStrength.getQuantity(), prescribedDailyDoseInUnitOfSubstanceStrength.getUnit(), substanceDefinedDailyDose.unit());
             } catch (Exception e) {
-                throw new ResponseStatusException(HttpStatus.PRECONDITION_FAILED, String.format("Mismatched Dose units for the medicine %s", snomedMedicationLabel), null);
+                throw new ResponseStatusException(HttpStatus.PRECONDITION_FAILED, String.format("Prescribed dosage could not be validated for %s. Reason: Invalid dose unit.", snomedMedicationLabel), null);
             }
             AggregatedMedicationsBySubstance aggregatedMedicationsBySubstance = aggregatedMedicationsBySubstanceMap.get(substance);
             if (aggregatedMedicationsBySubstance == null) {