We're all guilty of using our makeup for a bit longer than recommended

Just like food or medicine, your makeup has an expiration date or a period after opening otherwise known as the PAO.

How can you tell what it is? Look at your products and you'll see a little jar design with a number and letter 'M' in it, that's the number of months a product is good to use after opening.

Yet what if you've managed to rub that design away from repeated use?

Here are a few guidelines to follow when it comes to your beauty routine.

Mascara

On average you should replace your emotional support mascara every four to six months or as soon as it smells a bit off.

Also, take note if your wand starts to deposit more clumps than colour, that's a red flag and possibly future pink eye.

One thing you can do to avoid nasty bacteria sneaking into the formula close it tightly after each use and avoid pumping the wand in and out.

Eyeliner

Immediately bin your pencil liner if the tip starts oozing an oily substance or forms a white film.

Hang on to liquid liners for no more than six months, and dump them sooner if they thicken or smell like decaying roses.

You can't really give liquid liner a new lease of life but with your pencil regularly pare the top to remove germs.

Foundation

Most formulas - liquids, creams, and powder compacts - can last up to a year if kept out of direct sunlight and away from heaters.

Yet be wary if your liquid starts to separate, your cream thickens, or your compact develops a rubbery aroma, it's time to part ways.

Concealer

If you use stick formula, you'll know it's gone bad when it cracks or turns tough and elastic-like.

It's time to throw out your liquid concealer if it separates, appears oily, and/or smells rancid.

To extend the life of your concealer, try not to put your hands in the product container and screw the lid on tight.

Blush and eye shadow

Expect creams to last one year, powders about two. If your powder grows a white crust or starts to crumble before that time, chuck it.

If your cream decides to thicken and smell off make sure it joins the powder in the bin.

To extend the life of your beloved products, don't use your hands tighten the lid, and avoid heat and sunlight.

You can also protect powders by keeping them dry and storing them in a place other than the bathroom, where humidity can affect them.

Lipstick

Eight months is the standard for this makeup product unless - you guessed it - it starts to smell funky or changes texture, pretty much the rule that applies to all makeup.

Of course, if lipstick comes into contact with a cold sore or any type of infection, it's fit for the bin.

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