There isn’t a 50-something woman in the world who doesn’t want perfect-looking, glowy, age-defying skin.

But, if you think you’ve tried it all, you might want to take a leaf out of the younger generation’s book.

Celebrities such as Hailey Bieber are swearing by a secret ingredient, a retinol alternative called tretinoin (pronounced tret-in-oh-in), aka retinoic acid, which, if you’re not all over TikTok, is huge on the platform. Thousands upon thousands of Gen-Zers and millennials are sharing their before and after videos. With its promises of ‘glass skin’, the hype around tretinoin has seen it going viral on social media over the last 18 months.

‘I’ve seen a big increase in interest among my clients,’ says dermatologist Caitriona Ryan. ‘They all want brighter, clearer skin, reduced pore-size, a reduction in fine lines, and a generally more youthful appearance.’

We’re all for that. But what exactly is this skin-transforming magic ingredient?

‘Tretinoin is a prescription-strength topical retinoid, derived from vitamin A,’ says Ryan. ‘It is the active form of retinol, meaning that, unlike retinol, the body does not need to convert it into a form it can use. As such, it acts more directly and efficiently, making it significantly more potent than over-the-counter retinol products.’

Celebrities such as Hailey Bieber are swearing by a secret ingredient, a retinol alternative called tretinoin

Think of it like a coffee menu, says Mark Curry co-founder and chief executive of skincare brand Inkey List. Retinol is your light roast: it needs to be converted twice in the skin (to retinal, then to retinoic acid) before becoming bioavailable (accepted by your skin cells as the activator).

Retinal (retinaldehyde) is your medium roast. It needs only one conversion and is faster and more potent than retinol, and less harsh than tretinoin, but can be sensitising.

Tretinoin is your espresso. No conversion needed. Super effective, but can pack a punch. Each step away from retinoic acid means less irritation but slower results.

Dr Emma Craythorne, consultant dermatologist and founder of Klira skincare, explains: ‘The difference between the two is that retinol is about 20 per cent less strong than tretinoin.’

In the UK, tretinoin, which is one of the most extensively tested skincare ingredients available, is a prescription drug, which means it can’t be bought over the counter.

That might mean consulting a dermatologist, or trying one of the prescription skincare-by-post services, such as Dermatica (dermatica.co.uk), Skin & Me (skinandme.co.uk) or Klira (klira.skin) which, where appropriate, can prescribe a cream that contains tretinoin (from £24.99/month).

Tretinoin is a prescription-strength topical retinoid, derived from vitamin A

So, what are the benefits? Key ones include stimulating collagen production, which helps to reduce fine lines and improve skin elasticity and tightness, increasing cell turnover to improve texture and tone, reducing hyperpigmentation and sun damage, plus treating and preventing acne.

Skincare experts agree there are noticeable results on peri-menopausal and menopausal skin. ‘Consistent use [most dermatologists recommend daily at night after an introductory period] can result in improved skin texture, reduction in the appearance of fine lines, and increased elasticity and tightness,’ says Ryan.

‘After about six weeks of use, your skin will feel glowier and you will notice that when putting on make-up your skin will be smoother and reflects light better,’ Craythorne explains. ‘In a three to four-month period you should notice pigmentation start to go and after about nine months you’ll see a much more even skin tone.’

So, what are the downsides? ‘It is an active drug and it’s not just the active drug you’re putting on your face but also the formulation, the base that supports it,’ says Craythorne. Skin can become drier and go scaly.

Some people, she says, also get a purging – or eruption – of spots all coming out in one go. Plus, you must be diligent with your SPF. ‘There’s no point in doing all this reversal treatment if you’re not going to be using your SPF well.’

Ryan agrees. ‘Tretinoin can cause significant irritation when first used,’ she says. ‘This includes dryness, peeling, and redness so it must be introduced gradually.’

• Don’t use Tretinoin if pregnant. It may also not be suitable for sensitive skin, active eczema, rosacea or a compromised skin barrier.