People are only just discovering what this code on make-up containers means

Have you ever noticed those little cryptic codes on cosmetics and make-up containers – but never fully understood what they meant?

Well now, the blissfully unaware are discovering that they're pretty important, and their minds are blown.

Generally, there's a number on the packaging followed by 'M' standing for 'month'. The number before, whether that be 3M, 6M, 12M or 24M, is an indication of its shelf life. This is called a 'period after opening' (PAO) code.

According to the EU Cosmetics Regulation EC 1223/2009, an expiration date is required on the packaging if the shelf life is less than 30 months. If it's longer than 30 months, the PAO is not needed.

One beauty enthusiast even turned to Reddit and urged people to check the PAOs of their products. They went as far as to create labels as a reminder of when they can no longer be used.

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One person responded that while they have "literally never paid attention" to the numbers, they were experiencing minor eye issues and threw away "almost all" of their eye make-up. They added: "It was then that I realised I had been using some of it for over a year. So yeah... good call."

"This is smart," a second wrote. "The only product I’m serious about is mascara since eye infections are unpleasant and avoidable."

A statement from the Obelis Group, one of the largest regulatory centres in Europe, explained: "The PAO corresponds to the period during which the product is stable and can be used without posing any risk to the human health after opening,"

"Therefore, it includes a de facto assessment of the stability of the product towards the risk of the microbial contamination, following the first use."

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