There are many people who throw out their spoiled food, but never consider the dangers of outdated medications hiding in their medicine cabinets. Time takes its toll on medication by changing its chemical makeup and affecting its potency. For example, the active ingredient in aspirin, acetylsalicylic acid, breaks down into acetic acid with the passage of time.
Liquid medication can partially evaporate making it more potent.
Outdated ear and eye drops may no longer be sterile and may cause irritation or infection. Old aspirin may not hurt you except for prolonging a headache, but taking other outdated medicine can have more serious consequences. If the common antibiotic tetracycline becomes old, it can be toxic to your kidneys. Heart disease patients who carry nitroglycerin for the onset of a heart attack need to be sure their supply is always fresh. Storage Safety Medications don't have to be past their expiration date to become ineffective.