So it's something most of us neglect to do during our spring cleaning, but it's more important than cleaning out your pantry or digging through your crawlspace.

The American Medical Association recommends that everyone cleans out their medicine cabinet once per year, but how do you decide what stays and what goes?

A 1980s study conducted by the Food and Drug Administration revealed that many pills remain effective years after their posted expiry date. But how can you be sure that the ones in your medicine cabinet are?

Here are some guidelines to help you make decisions about what you're storing in your bathroom.

1. Should I save it, or toss it?

"In general, I would say many oral medications are safe to take a year or two beyond their marked expiration date," says Sara Bingel, PharmD, clinical pharmacist at New York City's Mount Sinai Hospital.

It's safe to save pain relieving drugs, such as Tylenol, Advil and Aspirin, allergy medication, stomach pills like Tums and Zantac, as well as cold and flu pills past their posted expiry dates.

You will want to toss any antibotics, nitroglycerine (for chest pain), life-saving medication, anything that is suspended in liquid and children's medication once it has reached its expiry date.

2. Why are expiry dates important?

Expiry dates are more about the potency level of the drug. Over time drugs can change their potency level to either be strong, or weaker. Once it changes it's potency level from the correct dosage, it is deemed as expired.

"How important is it that you need to get the right amount into your body?" says Michael J. Negrete, PharmD, CEO of the Pharmacy Foundation of California. "I might be willing to roll the dice with cough syrup. It's no big deal if the potency is down and it doesn't help my cough. But imagine an EpiPen, which keeps people from going into anaphylactic shock, not working."

Exact changes is potency is not available because drug companies don't want to spend the money to test for that.

"Let's say it takes a year for a drug's potency to decrease to 95%," says Paul Langevin, MD, director of cardiac anesthesiology at Waterbury Hospital in Waterbury, Connecticut. "I can't tell you six months later if it's at 93% potency or at 33%. That data's not available."

At the end of the day, if you're uncomfortable with guessing, go with the marked date on the box.

3. Where are you storing them?

Where do you keep your boxes of allergy medication? It's important to take note of where you're storing your medication when deciding what to keep and what to toss. If you keep it in a cool, dark drawer it could last for years after its expiry date. In comparison, if your medicine cabinet is located in a humid bathroom it is more likely to degrade and not last as long.

4. Liquid medication needs to be treated differently

You want to pay close attention to any liquid medication in your medicine cabinet. Gel capsules, liquids and any medication that is 'suspended' in a liquid is at risk of being contaminated with bacteria. Once those hit their expiry date, it's time to toss them.

5. Show antibiotics the trash can

When you get put on an antibiotic to treat an infection, it's best to toss the pills after you're done with them.

"I would advise patients never to take antibiotics that are expired," says Bingel. "They may not completely kill the bacteria and lead to a resistant infection."

What's worse is some antibiotics including tetracycline, a common prescription drug that has been shown to be toxic after it has reached its expiry date.

6. Never take the risk with kid's medication

You'll notice that a lot of kid's medications fall into the liquid or suspended liquid category, so you already know its time to go once it has past its date, but that's not the only reason it should be tossed.

"Because children are smaller and their metabolic systems aren't fully developed, I wouldn't hang on to kids' meds past the expiration dates," says Dr. Langevin. "Plus, a lot of medications for children are prepared in suspensions so the kids will take them, and those flavored liquids can decompose and acquire bacterial growth."

7. Toss anything that is not in a marked bottle

Did you pack up some meds to take on vacation with you? Anything not in its original packaging or container, toss them. You can no longer tell how old they are, or what they are, so it's not worth taking the risk.

This also includes ointments, which can be easily mistaken for creams.

8. Look for visual clues

I'm not saying you have to be some sort of private eye, but if you notice a pill crumbling to the touch, it's time to toss it. Other clues like smell and color could be a tip off that your pills have gone bad.

"Be suspicious of anything that looks out of the ordinary," says Negrete.

9. Safely discard old medication

Since some medication can be harmful to the environment and others living in your house, it's not advised to flush or just toss old medication in the trash.

Instead, place all medication in sealed bag. For solid medication, you can add some water to dissolve them as you discard the bag.

Make sure you remove any identifying information from the pill bottles so that your identity and information are not compromised if someone finds the empty container.

Also when you toss the bag in the trash, add kitty litter, coffee grounds or dust to deter children and animals from getting into them.

I know what I am doing tonight!