If you're still using the bottle of Witch Hazel that's been sitting in your bathroom cupboard since 2001, this one's for you, friend. 

Because here's the thing - beauty products don't last forever, and if you're continuing to use them well past their prime, you're going to have a bad time.

We know, we know - life would be much better if expired products didn't directly impact the health of your skin, but.... they do. They really do.

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In fact, expired skincare can get NASTY, causing everything from weird reactions and rashes to inflammation and a whole load of other things we don't want for your cute face.

So, how do you actually know when your products have reached their expiration? 

We spoke to Dr Sue Feng, Palmer's Chief Scientific Officer, and asked her about how well different skincare products hold up - and when it's time to replace your stash.

How do you know when your skincare is expired?

Figuring out what products you need to ditch is surprisingly easy. "The simplest way to know whether your skincare is expired is to check for an expiry date," said Dr Feng.

The ol' expiry date. Where do you find it?

Well, the symbol usually looks like a small tub or jar with a number inside it, and can usually be found on the underside or back of the product.

Listen: Have you been going through your makeup collection at home, trying to work out what’s expired and what hasn’t? Here's how to know when it’s time to chuck ‘em. Post continues below.

"If a product is open, you can check on the packaging for the little jar icon – the number printed within the jar icon indicates how many months the product can be safely used. Generally, water-based products like lotions are suitable for use for 12 months after opening, and oils are 24 months," explained Dr Feng.

So, what happens if you have some unopened stuff kicking around for ages? Is it still good to go or nah?

"If the product is old but unopened, or you can’t remember when you opened it, you’re going to have to rely on your senses," said Dr Feng. "If your product looks, smells or feels unusual – that is different to how you know it should be – then don’t use it."

Image: Giphy 

So, yeah. If something stings or tingles (but never used to), or smells kinda funky, wipe it straight off and bin it. "Throw it away rather than running the risk, your skin is way more important than that." It is! It really is.

What happens if you use expired skincare?

We're not scientists, but slapping old products onto your face can't be good for you, can it Dr Feng?

"Hopefully, if you unwittingly use expired skincare nothing remarkable will happen. But in many cases using expired skincare can have a detrimental impact to our skin," said Dr Feng.

What kind of impact?

"The greatest risks are failure of preservatives, failure of actives or chemical changes and reactions."

Dr Feng said if the preservatives fail in an expired product, it leaves room for icky bacteria to grow. Meaning? You're slapping one very gross concoction onto your face.

"This can lead to skin rashes, acne or infections due to contamination. If this occurs, a visit to the doctor will be needed to appropriately diagnose and treat the issue," she said.

Image: Giphy 

Yikes.

"Secondly, failure of actives is when the key active ingredients lose their efficacy. This can sometimes be benign, i.e. the product no longer delivers the desired effect or result. But think of sunscreen – if the active ingredient in a sunscreen fails, then your skin will be susceptible to UV damage and sunburn."

So, DON'T USE EXPIRED SUNSCREEN, YOU GUYS. 

If the active ingredients in your skincare products have gone off, then that 12 step Korean skincare routine is a giant waste of time. 

"Thirdly, chemical changes or reactions can occur if ingredients start to change over time. This could cause irritation, rashes or breakouts which can have long-term impacts."

Again, not ideal.

How can you make your products last as long as possible?

According to Dr Feng, if you store your products the correct way, they'll last way longer. This means taking them out of your bathroom (warm, humid, no good) and off your Instagram-worthy shelf that sits near your window.

"Beauty products should always be stored in a cool, dry and dark place, such as a cupboard. Storing products in your bathroom for example can be risky, as the space is often warm and humid. Warmth and humidity can encourage mould and bacteria growth, and UV light can cause some ingredients to degrade (vitamin C is a prime example)." 

Dr Feng said many ingredients are also sensitive to air exposure (this can cause certain ingredients to oxidise), so these should be packaged in airless containers and used pretty swiftly once opened. 

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Also, finish your skincare products before buying 345247 more. "I also recommend people try not to chop and change between products so often, giving opportunity for products to accumulate and deteriorate," said Dr Feng.

"We are always looking for the next best thing in skincare, but often classic, reliable products are the best. Find the formula that works for you and stick to it." Kinda makes sense, no?

"A solid skincare routine that involves regular and thorough (but not harsh) cleansing, suitable hydration and rigorous use of SPF is the best way to achieve beautiful skin, because it establishes consistency. And our skin performs best when not under the stress of adapting to new products every week or so," adds Dr Feng.

Any other tips for not ending up with a cupboard full of expired skincare?

"There is no need to get FOMO every time a new beauty product is released," said Dr Feng.

We know, we know. But... the pretty packaging! The hype! The waitlist! 

"If you do succumb to the lure of a new product but don’t find it knocks your socks off, give it to a friend (only if sanitary to do so) or throw it away right then and there!"

"Don't let disappointing products languish in your beauty cabinet only to remind you of their disappointment. Beauty is supposed to be a rejuvenating experience, not one that causes you grief or stress."

Anyone else now gearing up for a beauty cupboard cull? Let's do it.

Feature image: Getty

Are you guilty of hoarding some expired skincare and makeup? Share your comments with us below.