A medicine cabinet is a great place to keep grooming tools or toiletries but, despite the name, it's a terrible place to store medications. The temperature and humidity of a bathroom can make medications go bad more quickly than they otherwise would. Photo by Frankieleon.
Many drugs, especially those in pill form, can last for a long time (even longer than their expiration dates, in many cases). But that's only if they're stored in good conditions: cool, dry, dark places. Bathroom medicine cabinets fail two out of three: they tend to be hotspots for high temperatures and humidity.
A dresser drawer or a kitchen cabinet (away from the stove, of course) would be a better place. Also think about who can access the medications, since you'll want to keep them away from kids and pets. It's not unreasonable to keep meds in a lockbox to thwart marauding toddlers, and the US FDA recommends locking up anything that might appeal to curious teens.
Storing Your Medicine [HealthDay]