During the pandemic, Caroline Hirons started what she calls "a weird skincare revolution". At 5pm each day, Hirons would log onto Instagram Live and discuss skincare with her followers - many of which were already devoted fans, alongside some newcomers.

Hirons started off years ago with a prolific and thorough skincare blog, revered by beauty lovers the world over. Eventually she was approached to write a book, which led to her Skin Rocks app, and she now has over 700,000 followers on Instagram alone.

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Hirons is in Dublin working on the Arnotts Beauty Hub. The skincare expert caught up with Lottie Ryan on the Jennifer Zamparelli Show on RTÉ 2FM to discuss her 'desert island' products, the celeb skincare brands she doesn't rate and her two cents on cosmetic treatments.

The questions were repetitive, she says, but eternal ones: how to stop breakouts, what to use for certain skin types. For number one tip for all skin types and ages, however, is use an SPF from an early age. "When I first started coming to Ireland, 10-plus years ago, that was the hardest message. They would laugh me out of the stores.

"I'd just think, 'you're so pale!'" She said this was especially important for redheads with freckles – no surprise why she's pushing the SPF in Ireland, so.

So what would one of the most important names in skincare bring with her if she was stuck on a desert island? Hirons says it would be a facial mist, a balm cleanser and a really good moisturiser. As for brands, she'd opt for Kate Somerville, Sunday Riley and Deciem.

For those of us wanting to avoid spending a small fortune on skincare, she recommends The Ordinary and French pharmacy products.

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"If you're older and you want to treat the signs of ageing you're not happy with – I'm not saying getting older is a problem, getting older is the goal – if you can take care of the bookends in a more affordable fashion, which would be cleanser, moisturiser and SPF, you can spend the money that you do have in the middle, serums for things like pigmentation, lines and wrinkles."

For her, a skincare red flag would be "cheap scrubbing products". "Things that have, I call them remnants of fruit. Like peach husk! There's no need to scrub your face. If you think about how you sand a really beautiful mahogany table, you don't go in there with a few bricks. It's the finest sandpaper!"

Lottie revealed that following a social media trend for peels and over-exfoliation led to her skin breaking out badly. "It's like fashion", Hirons agrees. "It's the fine balance between how do I use the stuff I've got, and where do I start? And it's a big scope of questions."

Despite her mother and grandmother being in the beauty industry long before her, Hirons says she's still educating her mammy on certain products that come out. "I rarely say, everybody needs this [product.]"

She applies the same perspective to cosmetic procedures, saying it's up to the person. "Just because it happens to be on the face, it gets lumped in with skincare and beauty, but actually if you were someone who was having a nose job because you didn't like your nose, how is that anyone else's business?

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"Yes, there is the very, very rare occasion where you go, oh, that's a bit much. But I would never dream of saying to that person – unless it was like, my mum! – 'isn't that a bit much?'"

There are benefits to some treatments, she says. "Botox and filler are good for the structure of your skin, but when you have Botox and filler it doesn't do anything for the surface of your skin and the appearance. Good skincare is the skeleton of how good your skin can look."

Hirons is renowned for her honest takes on skincare, and that hasn't stopped, particularly in the wake of certain high-profile celebrity skincare launches. She tells Lottie that the Kate Moss and Stella McCartney ranges were "really bad".

"I think Stella does care about the ingredients", she says. "The product isn't crap. What I object to as somebody who's been in the industry a long time and is qualified ... if you're going to go for Botox and filler, you should go to a doctor or a nurse. Don't go to a facialist. I'm a facialist, I could give you Botox and filler in the UK because it's not regulated but I would never.

"The tone [of Stella's line] was so patronising that it drove me up the wall. It was very misjudged because people aren't where they were 10, 15 years ago. The customer is much more savvy."

On the price point issue, she said if you have the money for those products, crack on. But: "If you're going to credit card something just because it's made by Kate Moss or Stella McCartney, don't do it."

To listen to the full interview, click above.