Margot Robbie's go-to lip balm is an $8 nipple cream.

I love a good celebrity beauty tip. I’m always buying into the belief these people (and they are just people) somehow have the secrets to flawless skin/perfect hair that they’re just not sharing with the rest of us.

However, I rarely do get genuinely excited about a celebrity’s recommendation – mostly because without even looking up the price I know it will be many, many dollars out of my price range.

Enter Margot Robbie and her $8 solution to dry lips.

The actress told Elle Magazine her go-to lip balm isn't even a lip balm, but a nappy rash cream.

"And then my lip balm, I use Bepanthen, which is actually a nipple cream for breastfeeding mothers or diaper rash cream for babies," Robbie told the magazine this week.

"I have a conspiracy theory that lip balms actually have additives in them to dry your lips out so you keep buying them. But because Bepanthen is just a cream for dry skin, it works.

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"It's what I've used my whole life."

Yes, the 26-year-old's weapon of choice isn't a luxury elixir only available in the US, but something many breastfeeding mums probably already have in their bathroom cupboard.

The price and accessibility alone aren't why I'm so excited about this recommendation. I'm more than a little chuffed because (confession) I use Bepanthen. And as a fellow life-long Bepanthen user, I can also attest to its restorative powers.

I can also tell you that a 100g tube of the stuff (RRP $10.60 but available for $7.99 at Chemist Warehouse) will last you about a year, depending on how thirsty for moisture your lips are.

Margot and I (had to do that) aren't the only ones who recommend a nappy rash/nipple cream for everyday use on your face - fitness empire commander Kayla Itsines swears by Sudocrem to zap her pimples.

“Sudo cream… the same cream you use on your kids bums, I put on my face. It’s the bestttttttt!” the Adelaide personal trainer wrote on Instagram last year.

A post shared by KAYLA ITSINES (@kayla_itsines) on Aug 31, 2016 at 8:49pm PDT

“No pimples with this stuff, it works miracles and it’s so cheap! I’m telling you, thank me later.”

And while you're rushing out to your local chemist to stock up on nappy cream, pick up an extra eyebrow brush or toothbrush.

Margot Robbie also told Elle she has found using one is the best way to blend foundation into her hairline.

"My friend taught me this trick that I use it every day. When I put on foundation, I use an eyebrow brush or toothbrush to brush it into my hairline so that it all blends," she explained.

"Especially because I have blonde hair but tanned skin, if I don't blend it, it looks gross—you can see the foundation in my hair."

What's your favourite non-beauty beauty product?