As you sort through the old vitamin bottles in your medicine cabinet, your only clue to their general age may be the amount of dust on the bottle caps, especially if they don't have an expiration date. The U.S. Food and Drug Administration does not require that vitamin manufacturers place an expiration date on the products they sell, although some choose to do so. Vitamins do lose potency over time, so it is best to use them before their expiration date, according to IDEA Health and Fitness Association.
Vitamins lose potency after they've been on your shelf after a long period of time. Heat and humidity and your product's packaging are determining factors for shelf life. When stored under the same conditions, pressed vitamins--those that resemble aspirin tablets--lose potency more quickly than vitamins that are coated or come in capsule form.
Extending Vitamin Life
Your bathroom or kitchen isn't the best place to store vitamins, according to a report from Purdue University News Service. These areas of your home are too hot and humid. Refrigerating vitamins you take every day also isn't a good idea because opening and closing the cap allows condensation to form in the bottle. Your best bet is a dark storage space, such as a closet where you store linens, towels and clothing.
Throwing Vitamins Away
If you purchase vitamins without an expiration date, one way to give you an idea of how long to keep them around is to write the date of purchase somewhere on the label. If your vitamins do have an expiration date, throw them away after this time.
Don't dispose of expired vitamins and other old medications by pouring them down the sink or flushing them down the toilet. The U.S. Environmental Protection Agency states that they may end up in a nearby lake, river or other body of water that's used for your community water supply. Water treatment plants usually cannot remove them from wastewater. Instead, mix the old vitamins with coffee grounds or cat litter and place it in a sealed container or plastic bag. Dispose the bag or container in your outdoor trash bin as close as possible to the next scheduled trash pick-up.
According to a report from Harvard Medical School, it's not harmful to take expired vitamins. Because you don't know whether your dietary supplement is at near or full potency without a chemical analysis, however, it may be more efficient to discard them and purchase a new bottle. Eyeball the vitamin and note if it's changed color or tastes or smells different. If the physical properties of the tablets or capsules have changed, your vitamins may be better off in the trash bin.