It's easy with food, for the most part, to know when it's better in the bin than on your plate, but with beauty products, which rarely boast a written expiration date, it's a different story.

That handy stamp telling you when it's time to toss an item isn't mandatory on your lipstick or face cream and because of that fact, we often use beauty products that have either lost their effectiveness or contain more bacteria, mold and yeast than we'd like to know about.

Skip to see if your beauty products are expired now.

And why shouldn't we hold on to that liquid foundation until it's within a centimeter of its life? Or squeeze out that very last drop of moisturizer? We're spending hard earned money on this stuff, right? Right. But the likelihood is that if you have a beauty product that is expired, you probably haven't been using it.

So let's all take a moment to admit that we might all have a tendency to hoard and/or buy things we don't actually need because they're either on-trend or we've convinced ourselves that we do, in (illusory) fact, need them.

Well ladies, that perfume you bought ages ago and haven't spritzed on since the first week you purchased it isn't going to smell quite as lovely as it did at the department store. Sad, but true and don't worry, we're all guilty of holding on to things for a bit too long -- even if we haven't touched it in months.

So to help you figure out when all your beauty products should be chucked, and to share some tips that'll help you keep them in tip-top condition for as long as possible, we went to the beauty authorities. With their expert advice, you can save money and much-needed bathroom cabinet space by knowing what to trash and when.

Now, find out how long you should keep your beauty products.

Before we break down when to throw away what, there are certain rules to follow with any beauty product, says Min Kim, L'Oreal Portfolio Artist and hairstylist at Butterfly Studio Salon. Rule #1: "When in doubt, throw it out!"

She explains that you should always toss a product if it smells "off" or is "different from when you initially purchased it. Also, if the product starts to separate (solids at the bottom/fluids at the top), chances are it's time for it to go as well."

Rule #2: Avoid buying beauty products in "bulk sizing (giant sizes that will sit around for months or in packs of [multiple items]) to ensure that they will be fresher. Unless you have more than one person using the products, 12 ounces or less is the way to go," says Brook Harvey-Taylor, creator of Pacifica Perfume.

Tip 1: "Most preservative systems ensure the shelf life of products as well as keep bacterial contamination at bay once opened," says Harvey-Taylor. And since most beauty products do contain them, you only have to be extremely careful when it comes to products that don't have preservatives like your natural oil-based products like bath oils and some products labeled "organic." These should be "kept in the fridge once exposed to any air or hands � or they will become a free-radical magnet and wreak havoc on your skin rather than help [it]," she says.

Tip 2: When it comes to making products last, "limit [their] exposure to air. Air is the killer," she says, so "keep lids tight." Also, if you are using anything that comes in a jar or tub, "then be sure to wash your hands before use." The less you touch a product, the better.

Tip 3: Keep your beauty products out of your bathroom. Every time you shower, you steam up the room and moisture can get into your powders, eyeshadows, and liquids, diminishing the shelf life of your makeup, says Reed Cromwell IV, Director of Global Product Development and Innovation for Anastasia Beverly Hills.

Next: Learn when to toss your products

Body lotion
It can last a long time, says celebrity manicurist Skyy Hadley as she's "never seen any body lotion go bad." She says that it "if the lotion starts to become thin, you can add Vaseline to thicken the texture." Hadley also suggests "cleaning the pump (remove dry/crusty lotion from spout) every week or so, depending on how often it's used."

Perfume
If kept in the bottle fragrances "could really last for several years [as] alcohol is a perfect preservative," says Harvey-Taylor. Make sure to store it in a "cool, dark place," she continues, and not out on your vanity, where it can be exposed to heat, which can alter the scent.

Shampoo and conditioner
If they're unused and haven't been "exposed to extreme heat or sunlight," says Kim they'll last a couple of years. Also, make sure to keep lids closed to keep water out of the product as water and air will break apart the ingredient in the product.

Hairstyling products
Most last pretty long as most are packaged in some kind of bottle, tube or spray, says Kim. Keep an eye on any "products in jars or tubs as they tend to not last as long because repeated exposure to air can dry them out as well as contaminate [them] from exposure to dust and debris," she adds.