By Mary Kay Kleist

(CBS) — Have you ever pulled a bottle of pills out of your medicine cabinet only to see that they’re expired? Are they safe to take? And will they still work?

CBS 2’s Mary Kay Kleist reports.

Since the 1970’s, the FDA requires medications to have expiration dates. The government has looked at national stockpiles of medications and found that some may last as long as 15 years longer.

“But the key to that program was that all of those medications were kept in environmentally controlled conditions,” says Jan Engle of the University of Illinois Medical Center.

For the medicines in our cabinets, do these dates really matter?

“Once the expiration date is passed, there’s no guarantee that the drug is as potent as before,” Engle says.

That means taking expired medicine for a headache won’t harm you. It just may not end the throbbing pain. You can also take vitamins past the date, but they may lose some nutritional value.

But there are some medications that you must absolutely take before their expiration date.

“Things like nitroglycerine for chest pain, EpiPens for allergies, insulin for diabetes,” Engle advises. “Anything that’s for a life-threatening illness you want to make sure you use that product when it’s in date.”

But even “in date,” you have to be careful with ointments.

“Your hands are all over it, and if you’re not washing your hands, it can get contaminated. It may still be potent, but it may have bacteria growing in it, and it may not be a good idea to use it,” Engle says.

The same contamination can happen to eye drops if the bottle touches your eye.

It’s important to store your meds in the right place. Experts say the bathroom may not be the best choice, since it’s too steamy and warm. A kitchen cabinet away from the stove is better. Experts say no matter what the date on the bottle says, be alert if the consistency of your medicine changes.

“If you see something that looks like a crumbly tablet or if it doesn’t smell right or it doesn’t look right, your best bet is to throw it out and get a new product,” Engle says.

If you have questions about expiration dates, ask your pharmacist. They can guide you as to whether it’s safe to take that medication past an expiration date.

For information about disposing of old medications, click here.