1. A method for look-alike sound-alike medication error messaging, comprising: receiving, at a host server, a prescription transaction from a pharmacy POS device, wherein the prescription transaction received at the host server specifies a submitted drug product and a submitted daily dosage for the submitted drug product; determining, by the host server, that the submitted drug product specified by the prescription transaction is associated with at least one look-alike sound-alike (LASA) alternative drug product by comparing the submitted drug product specified by the prescription transaction to LASA drug pair data identifying similarities between drug products; determining, by the host server, that the submitted daily dosage specified by the prescription transaction is not within a typical dosage range for the submitted drug product specified by the prescription transaction, wherein the determination is based on a comparison of the submitted daily dosage specified by the prescription transaction to the typical dosage range for the submitted drug product specified by the prescription transaction; determining, by the host server, that the submitted daily dosage specified by the prescription transaction is within a typical dosage range for the at least one LASA alternative drug product identified in the LASA drug pair data, wherein the determination is based on a comparison of the submitted daily dosage specified by the prescription transaction to the typical dosage range for the at least one LASA alternative drug product identified in the LASA drug pair data; accessing at least one likelihood indicator value that represents a relative probability of whether the submitted drug product specified by the prescription transaction is submitted in error and instead should be one of the at least one LASA alternative drug products identified in the LASA drug pair data, wherein the at least one likelihood indicator value is based, at least in part, on a comparison of prescribing frequency of the submitted drug product specified by the prescription transaction to a prescribing frequency of the at least one LASA alternative drug product identified in the LASA drug pair data; determining, based on the at least one likelihood indicator value, that the prescribing frequency of the submitted drug product specified by the prescription transaction compared to the prescribing frequency of the at least one LASA alternative drug product identified in the LASA drug pair indicates an increased probability that the submitted drug product specified by the prescription transaction is submitted in error; determining that the prescription transaction should be rejected based, at least in part, on the determinations that: (a) the submitted drug product specified by the prescription transaction is associated with the at least one LASA alternative drug product identified in the LASA drug pair data; (b) the submitted daily dosage specified by the prescription transaction is within the typical dosage range for the at least one LASA alternative drug product identified in the LASA drug pair data and not within the typical dosage range for the submitted drug product specified by the prescription transaction; and (c) that the prescribing frequency of the submitted drug product specified by the prescription transaction compared to the prescribing frequency of the at least one LASA alternative drug product identified in the LASA drug pair indicates an increased probability that the submitted drug product specified by the prescription transaction is submitted in error; generating a reject message at the host server, wherein the reject message indicates a potential prescription error has been detected; and transmitting the reject message from the host server to the pharmacy POS device.