A gory photograph has been my “look at this freak” party piece for most of the summer. It's of a glassy-eyed woman, drugged up on Xanax and morphine, with eyeballs that appear to be weeping bloody tears, her skin red, oozing and bruised, and her eyelids glossy and raw like tuna tartare. When I showed it to my dad, with a jocular, “Look at this, euw, gross out, tee-hee,” he was visibly disturbed. He is a surgeon, used to sicko operating-room comedy, but he did not find this funny. “I can imagine some silly actress doing this, but not my daughter,” he said.

When, in the name of research for a television documentary, I allowed myself to dip a toe into the murky waters of cosmetic surgery, I thought I would barely get my feet wet. We decided to go to America, as it is a culture broadly more accepting, open and enthusiastic about cosmetic enhancement than over here. I thought I might have a bit of Botox, make my excuses and leave. Actually, in the course of interviewing some of the country's top practitioners, I got wet right up to my eyeballs, quite literally.

Previously, I had found cosmetic surgery curious, fascinating, not for me. Instinct told me it formed the deepest, darkest recesses of the misogynistic capitalist system that is the beauty industry. I dye and remove my hair; I have pedicures; someone else plucks my eyebrows. Slicing yourself up: ethically wrong, economically crippling and likely to make you look weird.

“Cosmetic medicine” is the best, if contradictory, catch-all term to describe the vast range of treatments available today, including lasers, peels, injectables, legally and scientifically dubious embryonic stem-cell work and hormone therapy, as well as the scalpel.

The noninvasive procedure - anything that is knife-free - is where the market is heading. In America, cosmetic-surgery procedures have increased by 140% in the past 10 years and noninvasive procedures by 740%. In the UK, the market more than tripled in the space of five years, and the vast majority of procedures are noninvasive.

These are entry-level procedures and they're unintimidating. They can can perk up your face and are reassuringly temporary - costing as little as £120; a decent face-lift is £8,000, and if you don't like it, you're stuffed. Having some cringingly raw photos of my unmade-up, 38-year-old, lived-in face presented to a panel of beauty-industry critics, who pointed out what made me look ugly/old/ordinary, brought me a little closer to the culture of what I can only call extreme self-improvement.

By the time I arrived in New York, I was interested, wondering what I could do to myself. In such a high-risk game, you only want the big-name dermatologists or esteemed aesthetic surgeons working on your face - and I had access to all of them. Clearly, my personal quasi-feminist standpoint, my moral objection to it all, was careful avoidance. I wasn't principled - I had just swerved the issue for cultural and financial reasons.

We nailed an appointment with Dr Fredric Brandt. Brandt is Madonna's guy - he's hot. They also call him the “baron of Botox” - he buys more Botox than any other person in the world. Him, the “don of needles”, he would work on my face.

But, like a kid in a sweet shop, I couldn't wait. While I was interviewing a Park Avenue cosmetic podiatrist, I got chatting to her colleague, a radiologist called Dr Everett Lautin. “Diagnosing” all the flab, sag, wonkiness and hollows in my face, he prescribed some needlework. As a radiologist, he is not qualified to work with a knife, but he can stick as many needles in it as he likes. Any qualified doctor can administer injectables in America, even a radiologist. (In the UK, the regulations are even looser - anyone can inject Botox provided they are “overseen” by someone authorised to prescribe it. Soon, if the government has its way, anyone will be able to administer non-surgical lasers: doctors, nurses, nail technicians, window cleaners - anyone.) The point being, Lautin is no Brandt. But he had a knowingly buffoonish air, which was a refreshing change from the smooth-talking charm-meisters, with the photos of their shock-and-awed, “all my own work” wives on their desks.

As we talked, Lautin was totally comfortable lampooning the Botox junkies, the women who aren't happy unless their faces are in permanent rictus. They say you choose your cosmetic doctor based on empathy - Lautin talked like James Stewart. As we chatted about the importance of keeping it subtle - the “European look” - I decided he was just the kind of guy I wanted injecting poisons and volumising materials into my face.

Impatient, I asked him if he could do me now. Checking his watch, he said things were tight, as he had a cocktail party to go to, but he would squeeze me in.

Forty minutes, £1,250 and 50 injections of Botox and Sculptra later, he dashed off. I went home for a much-needed medicinal gin. Anyone who describes injectables as painless may have had a little light Botox around the eyes. What I had was rough and painful.

The following morning, as I lay in the chair of “Madonna's guy”, I felt bruised. Brandt is jaw-dropping evidence of what happens when cosmetic dermatologists get high on their own supply - less 59-year-old man, more freaky porcelain doll in appearance. Did it put me off? Did it hell.

I told him I'd seen Lautin (he spat to his PR, “Why didn't anyone tell me she'd let a radiologist loose on her face?”), and then waited for him to refuse me. Did it put him off? Did it hell.

Another 20 injections. Being injected so repeatedly is like being stung by a swarm of wasps. This time it was Botox into my jawline and Restylane into my top lip; the latter hurt a lot. What was I thinking? Every time the needle penetrates your skin, you feel stupid, vulnerable and assailed, but, underneath, there is the corollary to the suffering: the prospect of looking good. Even though I looked an absolute wreck - bruised everywhere, swollen, green around the gills - I was riding high, looking forward to seeing the effects and buzzing off pain-induced adrenaline.

The truth is, expensive face creams can't change the way you look, but surgery and injections can. Morally, ethically, financially, there is something dangerous and fun about playing with your appearance. It's un-PC and it's body modification - but so is a tattoo, ear piercing, leg waxing, hair dyeing. They like to sell this stuff as personal style. Where this burgeoning industry comes from, however, is a sad and unhealthy place. Many of the doctors I met are serving career women, for whom looking fresher and younger is not about vanity and a terror of ageing, but more about professional necessity.

Dr Daniel Sister, a cosmetic doctor near my home in west London, says: “I deal with everyone from lawyers and accountants to bankers and prostitutes. Most of my clients work. Women in their thirties start worrying that younger women will steal their jobs.”

This is terrible and depressing. But it's incredibly uplifting, getting out of bed and going bleary-eyed to the mirror and seeing - “What's this?!” - a picture of health staring back. It's a pleasant surprise, daily. There is research to suggest that Botox injections can treat depression: if you can't make miserable expressions, you cannot experience the emotions so intensely.

Things only got weirder after we moved on from playing with needles in NY, to LA, where we flirted with knives and lasers. I was on the rollercoaster, it was a thrilling ride and, my, there was a hell of a lot more of it to go before I was going to get off.

It was pathetic how quickly I went from someone determined to embrace ageing with some grace, to someone who was willing to let a fairly inexperienced doctor remove some fat from my backside, take it to a lab, separate out the stem cells and then inject it back into my ageing, sunken cheeks, up through the inside of my mouth, while also, seeing as he is up there and has got me under a general anaesthetic, getting the knife out and “redraping” the sagging skin under my eyes like a pair of old curtains.

The fat transfer didn't happen. A chance phone call at the last minute, telling me that nobody should work on me following the Sculptra injections, made me call off the procedure that could have left me looking ridiculous. Looking like a freak, I always thought, would keep me away from cosmetic enhancement, but in America, you meet countless women who look weird, yet think they look great. I reckon it's easy to join them. Perhaps I already have.

When you monkey about with what nature intended, things do go wrong. The Restylane in my top lip has slipped - there's a funny lump that shouldn't be there. Since the Fraxel laser therapy on my eyes (performed in LA by Dr Persky), the aforementioned tuna tatare has faded and, certainly, my eyes look less baggy, but, still, seven weeks on, they are a weird brown colour. My forehead is glassy and does not move. A glassy brow is not considered good Botox, but I now like this egg-like badge of self-inflicted paralysis. I may go back for more.

People have commented, constantly, on how well I look, and it started the moment I walked out of Brandt's office, when the sound man told me: “You're a real Manhattan girl now. You look awesome.” Even Anna Davies, the serious, Oxbridge-educated, bluestocking director, liked my lips. My best mate, P, who I had thought would be mildly disgusted, said: “You look great. I haven't seen you like this since the mid-1990s.”

Once you are inside, it's hard to get out. At a certain point, the Botox won't be effective enough, and it will be time for an eye-lift, a neck-lift, a face-lift and so on. If you want to be dramatic about it, you could say that injectables are the weed to surgery's heroin. More pragmatically, if you're going to play the self-improvement game, you had better accept you're in it for life. Boob jobs last only 10 years; eye jobs require volumising materials to be injected regularly into the under-eye area to stop you looking hollow.

I'm already nervous about the moment, in a month or so, when my face starts to drop, and it'll be back to saggy old me, or, more to the point, back to the doctor's chair for another few shots of happy in my face, or another knuckle-bitingly painful procedure. I know, deep down, it's wrong. But, damn, I look good at the moment.

The Ugly Face of Beauty will be on Channel 4 on August 24

What I had done

Botox: I had about 50 injections from forehead to jaw to iron out wrinkles and sharpen definition of a sagging jawline. Mild bruising persisted for a week. Will last a few months. Cost: £1,000.

Sculptra: A dermal filler developed to make Aids sufferers less gaunt. I had about 12 injections in my cheek and lower-eye area to replace youthful shape and volume. My face was swollen for several days, and I had deep bruising on my cheeks for more than a week. Three or four subsequent treatments are required for optimum results; will last two years. Cost: £400.

Restylane: A dermal filler. I had about 10 injections in my top lip to straighten it out and add volume. My lips were tender and sore for a day and the beads of filler made me constantly lick my lips in confusion over the alien substance. Cost: £400.

Fraxel Re:pair: A laser over my entire eye area to remove excess skin, refine appearance and stimulate collagen production. Seriously damaged for two days, I sat in a darkened room, smothered in Vaseline, wiping my eyes every three hours (even through the night) with vinegar water. It never really hurt, however. Subsequently, tenderness and soreness for two weeks, then for three months I must never allow my eyes to make contact with the sun unprotected. Could last 10 years. Cost: £750.

What I didn't have done

Fat stem-cell transfer: Injections of your own adipose stem cells into the cheek and lower eye area to replace lost volume and stimulate the natural production of collagen. It is painful, you cannot fly for a week and you must quietly sit in a room taking lots of pills.

Lower-eye blepharoplasty: Surgical removal and rearrangement of skin, so that bags and wrinkles are erased. Again, it involves no flying and quietly sitting in a darkened room. Minimal scarring. For best aesthetic results, a maintenance programme is required to fill out hollows under eyes. Cost (with fat transfer): about £4,500.

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