As a needle approaches my face, I feel blind panic. Sitting in the chair, sweaty, make-up free and with felt-tip pen all over my face, I am really not loving the experience.
"Frown," says Dr Tapan Patel - the man to whom I have entrusted my 48-year-old mug - staring intently at the space between my eyes, and I do.
I feel a stab - of shame, as much as from the needle. For the past few months, I have been harbouring a terrible secret. A secret so awful I've not had the courage to tell even my husband. Or the children. Or, for that matter, the dog - and I tell him everything.
But here goes: I've surrendered to the needle. That's right, I'm talking Botox. Oh, and a little bit of hyaluronic acid, too, just for good measure.
The needle pierces my skin, and I feel an odd swishing and hear a slight squeaking noise as the toxin flows into the muscles of my forehead.
It's not exactly painful, but there is a sensation of pressure and a heavy feeling, like a tension headache.
Then it happens all over again. Dr Patel pauses to load another needle. This one looks rather bigger. He's moving down my face, to the jaw.
"Clench your teeth," he says. I tense. This time it does hurt, though I don't show it. He's injecting deep into the muscles that cause me to grind my teeth, the ones my dentist is always telling me off about.
Apparently, he has only one other patient who grinds their teeth as badly as me, and that's Roger Federer. Me and Rog, champion teeth grinders.
Anyway, Dr Patel apologises as I wince slightly. There's a rather sickly, crunchy sensation, like a spade hitting rock. He applies gentle pressure. The muscle yields, and the poison whooshes in.
This isn't just about my wrinkles, you see. I've endured more than a year of painful (and painfully expensive) gum and dental surgery to repair the damage caused by years of tooth grinding.
Hopefully, this will stop me from destroying it all. But I won't lie: the main reason I'm here is vanity. And I feel a bit of a hypocrite.
I, who always swore blind I would never "mess around" with my face; I, who, over the years, passed judgment on countless celebrities with their frozen expressions and fixed smiles.
Madonna, Uma, Nicole, Meg: I owe you all an apology. Because now I'm 48-and-three-quarters, I finally understand why you do it.
Let's be frank, it's not nice when you catch a glimpse of your reflection on your laptop screen and feel no connection to the aged harridan peering back.
Even if you've never considered yourself much of a looker (and I haven't), it's depressing to see the slackness in your forehead, the way the corners of your mouth turn down when you're not smiling, the blurring of a once-firm jawline.
It's deflating when your 12-year-old keeps asking why you look so cross when, in fact, you're feeling rather jolly. It's boring and time-consuming to feel you can no longer leave the house without applying make-up - perhaps not a full face, but at least a bit of concealer to cover the wells of black beneath the eyes.
When you're young and firm of jaw, it's so easy to sneer. You have no idea of the horrors to come. Rather like childbirth, you have to experience it to understand it.
You simply cannot imagine yourself as the sort of vain megalomaniac so desperate to halt the inevitable passage of time that you'd be prepared to have poison injected into your face. You can't possibly understand why a person wouldn't want to just grow old gracefully, wear their wrinkles with pride as a badge of honour and a sign of a life well-lived.
Besides, isn't it a well-known fact that this stuff doesn't work? Well, it does insofar as it freezes the muscles; but surely it looks terrible?
It's been proven countless times: Botox - and fillers, of which more later - don't make a person look younger, they just remove all the character from their face.
I sat opposite a very high-powered casting agent at supper the other night. We got talking about Hollywood. She bemoaned the fact she finds it increasingly hard to come by good actresses who haven't had "work".
"It makes them impossible to put forward for 'serious' jobs," she said. "They simply don't have the expression in their faces to convey the necessary emotions.
"At least with Botox, it wears off," she continued. "If they have bad fillers, it's a nightmare. You see all kinds of horrors; lumps and bumps beneath the skin, weird swellings . . . and with HD [high-definition television], it's hard to hide that kind of thing.
"Some literally cannot work because of what they've had injected into their faces."
And yet, here am I, doing precisely that. The thing I said I would never do, the thing that has been the downfall of so many women clinging desperately to the raft of youth - and the one thing guaranteed to infuriate all my feminist girlfriends.
It's not as though I can claim ignorance. After all, I've been writing about this kind of stuff for years now.
My life is spent touring plastic surgery conferences, absorbing the latest techniques, marvelling at the lengths women (and men) will go to in order to improve or alter their appearance.
I've seen things that would make your toes curl, witnessed car-crash procedures and been shown contraptions that look as if they belong in a museum of medieval torture.
For years, I've preached abstinence. I'm always telling people that the key to looking your best is a healthy diet, lots of exercise, learning to relax. That superficial treatments don't work, that they don't last and only lead to more.
So why the sudden change of heart? After all, as a seasoned beauty writer, I can have my pick of any procedure. People are queuing up to offer me free laser treatments, free liposuction, free fat-freezing - the list is endless.
Trouble is, I've never trusted any of them enough to let them loose on myself.
And that is what's really changed. And it's because of the industry itself. Of course, the cowboys are still out there. But there's a definite sense the good guys - the ones who are properly qualified and responsible and dedicated to good practice - are starting to win.
Put simply, frozen forehead and trout-pout merchants are on their way out. It's not just that the general public are wise to their patter. It's also the fact that techniques and the materials used are becoming ever-more sophisticated.
Although the non-surgical industry is not yet properly regulated, those who employ best practice - the doctors and surgeons who take their jobs and reputations very seriously - have learnt an awful lot from their mistakes, and those of others.
Put it this way: five years ago, I would never have dreamt of doing this. It's only recently, as techniques have been refined, as substances used have improved and as responsible practitioners have started sharing their discoveries and fly-by-night operators named and shamed and forced out of the industry, that I've even considered it.
Truth is, the bowling-ball foreheads and pillow faces you see lunching or strolling around shoe stores are ghosts of the past. The future is one of restraint.
I know that; Dr Patel knows that. But to my friends and family, this is still a world that creates Brides of Wildensteins. There is more stigma attached to this kind of thing than to almost anything else in the beauty industry, except perhaps ludicrous breast enhancement.
And I know if it goes wrong, I will deserve - and rightly receive - zero sympathy.
It's for this reason that, after my first session with Dr Patel, I find myself telling gigantic fibs to all and sundry - including my husband.
In retrospect, this turns out to be a futile exercise because when I return from my first treatment, I look like I've gone several rounds with Mike Tyson.
There are purple bruises under my eyes and along my jawline. The area beneath my left eye is slightly swollen. There is really no getting away from the fact that I don't look great. I have no choice but to 'fess up.
Naturally, I sugar the pill. I tell him I'm doing it for work, that obviously I would have preferred not to, but that my editor insisted.
He knows me too well to buy that story. Nevertheless, he is restrained.
"I thought these things were meant to make you look better, not like you've been in a fight?" he says wryly, and then makes me a gin and tonic.
The following morning, the swelling around my eye is worse. It takes a very long time to cover up the bruises, and I find myself reaching for dark glasses in true Park Avenue Princess style.
But, despite all that, I can already see something that makes me slightly skittish with excitement: the bags - nay, troughs - under my eyes have all but disappeared.
I've described the Botox already but, in fact, that is not the whole picture. Dr Patel's speciality is something called the Eight-Point Facelift, which uses hyaluronic acid to recalibrate the contours of the face, tackling the most common signs of ageing.
(Though with the Botox in my forehead and jaw, I, naturally, have gone two better and had a ten-point treatment.)
Dr Patel's approach is less about just smoothing out wrinkles (very 20th century) and more about topography.
A young face is broadly heart-shaped: a narrow chin, wide cheekbones, plump, collagen-rich facial tissue.
As we age, that picture begins to reverse. As we lose collagen and our muscles slacken, the jawline softens and widens, the face becomes, overall, heavier in the jowls and the cheekbones recede.
The brain can detect these signals in the blink of an eye. Our reptilian brains - the oldest and most instinctual part of our psyche - can instantly differentiate between a young (and therefore fertile) face and an older (infertile or less fertile) face. And, being fundamentally Darwinian creatures, we are all - male and female - drawn more to the former.
This simple, anthropological fact is the reason older women often describe themselves as becoming invisible.
Other factors come into play, too, of course: a thicker waist, thinner hair, dull skin colour; but the face, and particularly the eyes, are such a magnet for the human gaze that, like it or not, we make instantaneous judgments that leave long-lasting impressions.
It's also because of this that women with strangely smooth foreheads and bizarrely stretched skin look so weird. No one, unless he or she is unlucky enough to have palsy, has a naturally frozen forehead. Everyone's face creases when it moves. Anything else is just freaky.
Dr Patel is one of the very few experts - along with Dr Vicky Dondos of London's Medicetics Clinic, who is also an advocate of the less-is-more approach - who genuinely have the intelligence to understand this.
Having looked closely at the work he has done on others, it's clear he has an artist's eye for shape, tone and texture. He understands it's not airbrushed artificiality we crave - just a slightly less careworn version of ourselves.
And that, despite the bruising and the puffiness, is what I'm starting to see when I look in the mirror around day four. Because, although the Botox will not take effect for a few days, the hyaluronic acid plumping agent (identical to the stuff our body produces itself) has already done its work.
By injecting minuscule amounts of hyaluronic acid (a naturally occurring substance that can hold 1,000 times its own weight in water) around the bottom of my eye sockets, Dr Patel has put back what 48-and-three-quarter years of gravity, stress and genes (under-eye shadows are hereditary) have taken away.
And instead of looking like a rather sad panda, I look bright-eyed and bushy-tailed.
This is a very new technique, and it requires the utmost skill and precision. If you get it wrong, you risk having bags under the eyes that resemble lumpy porridge. Luckily, Dr Patel's got it right.
The other notable differences are the corners of my mouth. Again, a tiny amount of filler has gone a long way and, now, they don't sag. I've had a few drops in my cheekbones, too, to make them infinitesimally sharper.
After a few days, I have some friends over for supper. The women - one a publisher, the other a fellow journalist - eye me with some suspicion. "You look annoyingly well," says one.
"Yes, why aren't you knackered like us?" asks the other. "It's your hair, isn't it? Or new make-up?"
After a few minutes, I confess. They are both horrified and thrilled, as though I were admitting to an illicit affair. We move to another room, leaving the men to their discussions.
"Ooh," says the journalist (a leading feminist writer), turning a desk lamp on me. "Ooh, it's good."
"Very, very good," says the publisher. "Quick, give me his number before the piece goes to press."
We are now three months on, and I've got used to my new face. The Botox in my jaw has been especially successful, since it has reduced my teeth grinding, which means I sleep better (and so does my poor husband).
My dentist, too, is delighted because I'm not destroying all his careful work. And it has had the desired effect of reducing the bulk of those mandibles, which has very subtly shrunk the width of my jaw.
So, yes, what can I say? I'm a terrible person. But I don't care, I love it. Or, at least, I do now that it's all over.
The effects of the Botox will wear off in a few months. The hyaluronic acid will hang around rather longer, fading over time, roughly 18 months, but it varies from person to person.
So don't hate me too much: I'll be back to looking like a tired old hag in time for my 50th birthday.
Unless, of course, I decide to go back for more . . .
- Daily Mail