Although botulinum toxin A was first approved in the US in 1989 for the treatment of eye muscle disorders, Botox wasn’t Hollywood-approved to address the ravages of time until around the mid-90s. It was frowned on initially, though naturally not by the celebrities who’d had it, as they could no longer frown. Directors would complain that actors couldn’t properly emote, having disabled half their muscles. It’s a risk, Dr Miriam Adebibe says, as she hovers with a needle over my forehead, ready to give me my first jab, at Victor & Garth, the east London clinic she co-founded with Dr Lauren Hamilton. “If it goes a little bit too far, you start to have a slightly dead look, you smile and there’s a lack of warmth that goes with that. Your facial expressions are not matching how you feel.” I have no personal anxiety at all. Adebibe is a surgeon who left the NHS exhausted by the pandemic and its aftermath. I’ve never had so much anatomical expertise pointed squarely at my face.

By the 00s, the aesthetic treatment was widely available to the general population – dentists could administer it after a daylong course, though it wouldn’t be until 2018 that Superdrug would start offering it. Consumer forecasters were anticipating a million-strong market by 2020, which turned out to be pretty close – by 2021, the estimate was that 900,000 injections were carried out a year in Britain (though some of those will be to the same people).

Nevertheless, it was viewed with suspicion that was twofold: one, that it was a self-indulgent vanity; two, that it looked very unnatural, particularly if used repeatedly over time. Whenever a star appeared shiny in a photo, she was considered a Botox tragedy, even though, looking back, she might just have been sweating. None of these preconceptions were necessarily wrong. It is quite a lot of money to spend on your face, if you’re just a regular citizen whose face isn’t their passport. Injections in one or two areas will cost between £200 and £300 now, but regulation in the sector is sparse, so it could easily have cost you the same or more 10 years ago. I spoke to one woman, Jay, who was charged £260 for two injections in 2010, when she had just turned 30.

Over time, treatments got more refined, prices stabilised and attitudes changed. Emma, 51, had her first treatment at 45. “I was becoming quite aware of ageing,” she says. “I went under the radar and didn’t really tell people. But if someone asked me directly, I wouldn’t lie. I wouldn’t say: ‘No, no, I just drink a lot of water.’” She has noticed two changes over these six years – first, practitioners have refined the dose so you don’t feel as if you have a really heavy, frozen forehead afterwards. Second, everyone is having it. “It’s really standard in the UK. Once you’ve had it done, you can identify it in others. If I see a woman my age with very dewy-looking skin, she’s had work. In reality, a 50-year-old woman that doesn’t look tired has had something done.”

Adverse effects were rare, to judge from the reported incidents – 188 adverse reactions reported to regulators over 29 years – although a study last year concluded that there were many more incidents of bruising, headaches and temporary muscle freeze that went unreported.

The American model Chrissy Teigen distilled the spirit of the 2010s when she said: “Everything about me is fake apart from my cheeks – fake, fake, fake.” It’s the spirit of the digital native, really: let’s just stop pretending that these faces, these bodies, these lives we’re showing each other are real. We all know what goes into them.

Lindsay Stark, 46, was Botox-curious but still had last century’s preconceptions. “I thought it was reserved for the glamorous, and I suppose I had a vision of frozen celebrities, who’d ended up looking really abnormal.” At 41, she mentioned to a friend she was thinking about it, “and she said: ‘Oh, I’ve been having it done for ages.’” Stark didn’t tell her partner, and he didn’t notice, and then after a few times she did tell him, and now he does notice, or maybe he just says that.

The more recent trend, though, is for “baby Botox” or “preventive” or “barely there”, subtle injections for the under-35s that stop the rot before it starts. So, along with old-timers coming round to the idea of Botox and sloughing off its taboo, it is no wonder the market is booming. Botox, along with dermal fillers, now accounts for nine out of 10 cosmetic procedures.

Chloe Mac Donnell, the Guardian’s deputy fashion and lifestyle editor, breaks it down into three main groups. First, women in their mid-40s to mid-50s catching up with advances that have made Botox more subtle and less celeb. Second, women in their 30s being “a lot more open in general”, and also a lot more into “luxury, hi-tech treatments (everyone uses retinol, LED face masks, injectables, non-injectables, micro-needling)”. And finally, women in their 20s having Botox in this age-prevention spirit, their attitude to injectables and fillers fuelled to an extent by the Love Island vibe, which is socially frank (they’ll tend not to hide any work) and aesthetically fake – “the big lips, the plump cheeks, the no expression”.

How on earth could Botox prevent wrinkles in the future, though, when the injections themselves last only three months? And before we answer that – which we can, by the way – does it really make any difference?

Adebibe asked me at the start what my current skincare routine was, and I replied: “I wash my face.” “With anything?” “A flannel.” No moisturiser, no sunscreen, no soap, no serum, no unguents of any kind. Call me the radical control experiment – and not in the sense of: “Does anything make any difference?” We can answer that really easily: my sister uses everything under the sun and she looks younger than me, even though she’s older, a fact of which I like to make constant public record. What I mean is, I don’t really mind where I get injected and I’m not overly invested in whether or not, at 49, I’m too far gone for it to work.

The most common three areas for Botox are the frown lines, the forehead creases and the crows’ feet. Some lines I want to keep; I earned those deep creases with my hard thoughts. Not all of the results, Adebibe says, will be obvious. “The little trio of muscles responsible for bringing the eyebrows in and down, when you relieve them of their duties, it causes the inside of the eyebrows to slightly elevate.” So you don’t necessarily get rid of the frown lines, “you just look fresher. Like you’ve had a super-good night’s sleep. The way it works,” she says (I can’t recommend enough getting this done by a doctor – they’re so plausible), “is that it’s injected into certain muscle groups and it stays in that area for just three days, during which it disrupts the receptor where the nerve comes to speak to the muscle. Over the following two weeks, you will find it harder and harder to make that expression. By two weeks, you’ve got your full response.”

On day 10, something weird happened. I had just dropped off the kids and was pulling out of my ex-husband’s crescent, which is always a nightmare – people don’t let you out because it’s covered in signs saying “private road”, and they think: “Screw you, rich person.” But a grey van actually reversed a bit on an A-road to beckon me out, and this happened again and again: other drivers were nicer; someone picked something up for me in Tesco; someone else made a friendly remark about my trainers, and I swear to God, it’s not because I look younger, it’s because I’m not scowling, and this is an effect that can be seen through two windscreens.

I didn’t speak to a single person who didn’t think Botox had made them look less forbidding. “I’d catch myself when I was driving,” Stark says, “in the rearview mirror, and think: ‘Why am I frowning?’ I’d be sitting at traffic lights, trying to stretch out my forehead with my fingers.”

This year, researchers at the University of California San Diego released a study showing anxiety levels were between 20% and 70% lower in people who have had Botox (within the three months that it’s effective). It feels slightly iffy because of that range (20 to 70 is quite the tolerance band), but the dataset was big (more than 40,000) and the proposition itself is credible. If the face you see in the mirror, or reflected in a shop window, is agreeable and not dissatisfied, it could plausibly make you less self-critical, in minute increments, many times a day.

Dr Michael Reilly, a facial plastic and reconstructive surgeon at Medstar Georgetown University hospital in Washington DC, recently posited a more physiological effect: “When you can’t furrow your brow or show the emotions of concern or fear or panic, there is likely a calming effect on the nerve pathways that feed back to your brain that then allow you to actually not feel that emotion quite as much.”

I now genuinely can’t frown. All I can do is kind of wiggle my eyebrows, like a children’s entertainer. By day 12, I was spending time with a work experience kid, and she said my forehead looked like an egg. Because she still has a full range of facial expression, I saw a trace of anxiety cross her face. “A beautiful egg,” she amended.

This interrupts the common narrative around beauty procedures, that they prey on people’s insecurities while simultaneously jacking up the grooming standards that make people feel insecure in the first place. In 2019, the Joint Council for Cosmetic Practitioners instructed its members to check before they administered Botox that their patients weren’t seeking it for reasons of poor mental health. I found that out after I had it, so when Adebibe asked: “Are you anxious, or depressed? Do you currently hate yourself?”, I was incredibly surprised. In a salon that smelled like berries, with this elegant, lineless expert, a really fun photographer and her beefy assistant, I was having the time of my life. I thought that was obvious.

As with anything that may enhance or deplete your mental health, depending on the study (MDMA, marriage), it’s the young that people worry about. I’m a bit agnostic about that, since the construction of youth as a state of vulnerability in and of itself is fundamentally bogus. The much more pressing question is, does Botox do anything for the under-35s? Because if not then “baby Botox” is just a rip-off. It helps if we understand how it works.

“All Botox does is prevent the degradation of your natural collagen,” Adebibe says, “because you’re relaxing the muscles that are constantly pulling on the skin. Each time the muscle pulls on the skin, the elasticity decreases; it’s crunching down on the collagen over and over, and that’s degrading your collagen.” The wrinkle is just a symptom of the depleted collagen, not the cause. So you don’t have to wait for it to appear; indeed, it’s probably better to pre-empt it.

Sidebar here: there’s no point having only Botox. “There are several ingredients that are shown in studies to change your skin at a cellular level,” Adebibe says. “Vitamins A, C and E at a minimum; vitamin B is very important, vitamin D is also quite important – topically, not just from diet.” But your diet should also be strong on all the vegetables of the rainbow, she adds, and maybe don’t smoke or drink so much.

The new celebrity trend, meanwhile, is Botox everywhere: in your hands, in your knees – there are so many areas that are just dead giveaways for ageing. I asked Adebibe whether she had ever injected anywhere except the face, and she said: “Only as a surgeon, in the anus.” And I started laughing, and she, because she is a doctor, and not some kind of halfwit, did not laugh at the word anus and continued: “It’s very hard to heal a wound around the sphincter because the muscles are so tight.” By now I was really laughing hard, and the fact that she still wasn’t laughing and would never laugh just made it worse, and I momentarily started panicking that I was never going to stop laughing. “Not to worry,” said a voice inside, “you won’t get any laughter lines.” The anti-anxiety effect had already begun.