This question gets asked at least once a week. Oil based injectables can least years after exp date w/o losing any potency as long as they are stored properly(in a cool, dry, dark place). Orals will last a year or so w/o losing potency when stored under the same conditions-blister paks may last a bit longer.
FYI- A lot of guys keep their gear in ther medicine chest in the bathroom. Next to storing gear in the glove compartment or trunk of your car in the summer, this is the worst place to store your gear long term due to temp changes, steam, etc. I try to find the coolest, darkest closet in my natty friend's house and store my gear there in a fireproof lock box I bought at Small Mart.