Your feed room is a logical and appropriate place to keep your horse’s medications briefly, but it may not be the best place to store them long-term. Temperature and humidity fluctuations in barns can alter the composition of medications. Liquid and paste medications may become clouded or separate as they freeze and thaw, but compromised pills and powders may show no outward signs. Medications that have gone through multiple or extreme fluctuations may no longer be safe or effective. Keep in mind that expiration dates are determined by testing after storage in optimal conditions.
and pastes are best stored in a climate-controlled space that keeps them at the temperature range indicated on the label. The house or a heated tack room or garage is one option, as is a refrigerator. For powders and pills, you can store the amount you are likely to use in a week in the feed room, but keep the rest in a place with a consistent temperature to protect their long-term stability.