You know it's time to throw out your lip wear when...

We're all guilty of owning that one lone make-up item we've had since before the creation of the world which just sits in our make-up bag. For some, it's not even just one item, its several items.

While some make-up artistes argue that there's no such thing as a useless make-up product, the fact remains that they're products which have a shelf life, after which said item could begin to pose a threat to health.

So how long should we keep our make-up products, or in this case specifically - lip wear before it becomes a potential harbinger of cancer?

We did a little research and here's what we found out.