It's tough to keep track of the ever-changing stock of items in your medicine cabinet. Before you know it, those little shelves might end up full of ineffective and expired products that should probably be thrown in the trash.

To keep things under control, experts recommend taking a hard look at your medicine cabinet pretty frequently.

"I tell people, when you change your clocks, go through your medicine cabinet," Heather Free, PharmD, AAHIVP, spokesperson for the American Pharmacists Association, said.

Ready to clean out the worst offenders? Here's when experts say you should toss 11 popular items.

1. A toothbrush that's more than four months old

The American Dental Association (ADA) says it's best to replace your toothbrush every three to four months, or sooner if the bristles become frayed.

There's not enough evidence to say that germs on an old toothbrush can make you sick, the ADA notes. But a worn-down toothbrush will clean your teeth less effectively.

2. Toothpaste that's several years old

Expired toothpaste isn't dangerous to use, but if it's really old – think several years past its printed expiration date – its fluoride may not work properly anymore, dentist Joel H. Berg told the New York Times.

Its consistency could also change after a while, making it tough to squeeze out of the tube.

3. Any expired sunscreen

The Food and Drug Administration (FDA) requires that all sunscreens keep their original strength for three years.

After that, there's no guarantee that the product will protect your skin from harmful UV radiation. It might still work – but you don't want to risk a painful sunburn to find out.

The AAD recommends getting rid of any sunscreen past the expiration date printed on the packaging.

If there's no date listed, toss the sunscreen after three years. Also replace any sunscreen that's changed in colour or consistency since you purchased it.

4. Cosmetics that have changed colour, odour, or consistency – or grown bacteria

There are four changes that may signal when it's time to get rid of face cream, makeup, and other beauty products, according to the anonymous pharmacist who writes The Cosmetist blog.

The first is a change in colour: A little yellowing is usually no big deal, but look out for dramatic changes in a product's hue.

Next, there's odour. It's normal for a product's scent to lose potency over time, but again, beware of dramatic changes. A rancid smell, in particular, indicates that oils in your product have gone bad.

Changes in consistency can also indicate that it's time to throw out a product. This is especially true when it comes to sunscreen, The Cosmetist explained – it may not work as promised

Finally, check for bacteria or fungi in the form of black or gray growths. In case it's not obvious, products with such growths should be thrown out immediately.

5. Expired medications

FDA rules require that all medicines come with an expiration date – it's the date at which the manufacturer can guarantee the full potency and safety of the drug," according to the Harvard School of Public Health (HSPH).

But just because that date passes, doesn't mean a medicine immediately stops working. In fact, a US government study found 90 percent of more than 100 prescription and over-the-counter drugs were still safe and effective even 15 years after the expiration date passed.

Still, Free recommends sticking to those dates. "Right now what I tell patients is to follow the true expiration dates [on packages] just to be cautious," she said.

This is especially true when it comes to nitroglycerin, insulin, and liquid antibiotics – three medications HSPH says you should never ever use past the expiration date.

When in doubt, consult a pharmacist. And if you do throw out a medicine, follow these FDA guidelines

One final note: Free said medicines should be stored in a cool dry place – and that bathrooms and kitchens are generally a bad choice due to their heat and moisture.

Try moving yourself to your nightstand or a bedroom closet instead.

6. Acne products that have been open for a few months

Dermatologist Amy Weschler told Allure that acne products with benzoyl peroxide and salicylic acid need to be tossed after four to six months.

That's because these two ingredients tend to decay quickly.

7. Rubbing alcohol and hydrogen peroxide you've had for years

Free said that disinfectants like rubbing alcohol and hydrogen peroxide can become less effective over a long period of time, and recommended buying smaller bottles if you don't use them very often.

Toss them after the printed expiration date.

8. Old contact lens cases

The American Academy of Ophthalmology says you should replace your contact lens case at least every three months.

Since your fingers come in contact with lens cases, they can become a breeding ground for bacteria that cause eye infections.

9. Expired contact lens solution

You should never ever use expired contact solution even if the bottle is still full, according to FDA optometrist Bernard P. Lepri.

In an interview with Medscape, Lepri explained that expired solution can end up contaminated – and using it could lead to infections, vision loss, and (in extreme cases) blindness.

10. That giant tub of petroleum jelly you rarely use

Free explained that your fingers can introduce bacteria into a tub of petroleum jelly every time you touch it. Next time you go through your medicine cabinet, it's probably wise to get rid of any ancient containers you've been holding on to.

Free's advice for the future: "Buy smaller containers."

11. Old tampons or tampons with torn wrappers

Tampons have a shelf life of about five years, gynecologist Alyssa Dweck told Women's Health.

That's because they can grow mold, especially if they're stored in a moist, steamy bathroom.

Don't forget to check the wrapper, too. Dweck previously told us that you should always make sure a tampon's packaging is intact before you insert one.

It ensures that the tampon isn't contaminated, and it's one way to protect yourself against toxic shock syndrome  –the potentially fatal illness that is sometimes linked to tampon use.

This article was originally published by Business Insider.

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