Once opened how long is an infant medicine good? its stored in a refrigerator..

Depends on the med: Some infant medicines do not require refrigeration & may last for weeks/months or more. Others begin to lose strength as soon as water is added to their powder base & may be good only until the projected end of a treatment + a couple of days. A typical antibiotic, amoxicillin, is good for about 2wks if refrigerated but only a week at room temperature. Check with pharmacist if needed.

I am presuming: You are asking about antibiotcs. Once they are mixed into a suspension, they are only good for 14 days regardless of expiration date.You need to discard them.Keeping them and hoping to use them the next time around is not a good idea.It is useless since the active ingredients are gone.It may pose a risk rather than a benefit by chancing it.