Discussions

I have a friend who keeps all her prescription drugs in a ziploc baggie... and while that is strange enough in itself, she also insists on keeping any number of medications way past the date on them. I know she has some antibiotics that she's carried around for at least 4 years, and insists that they'll be just fine if she ever needs them. My question is ... does anyone know what happens to the medications themselves after the expiry date? Do the antibiotics simply not work any more ? What about pain killers ? Cough and cold medications? Do they become poisonous or simply not be effective any longer?