In an effort to not be wasteful and save money, clients often ask veterinarians whether or not it is safe to use these drugs if they are expired. Little is known about the risk involved with administering expired oral medications. The expiration date is the time in which the drug can be expected to work effectively. Therefore, in order to achieve the appropriate response to treatment, it is best to not use expired medications. This will save money in the long run with quicker response to therapy, fewer veterinary consultations, and avoiding potential medical emergencies due to expired drug administration.
Of biggest concern is expired antibiotics. Antibiotics that are not 100% effective encourage resistance and may extend the infection and necessitate a 2nd or 3rd antibiotic course, costing more money.
Also there are many times when the course of treatment will be changed based on a horse’s response to pain medication. The extreme example is sending a colic to surgery because it is not responding to Banamine. It greatly complicates the clinical picture if the Banamine that was used is expired and we are not sure if it works.
One final note, it is NEVER ok to purposefully overdose a medication because it is expired and may not work as well.