As any long-distance runner knows, there are a number of cardinal rules when it comes to marathons and, while waiting at the start line for my third, I realise I have broken most of them. My general health is poor, in fact I woke coughing up so much phlegm that I was reminded of Slimer from Ghostbusters; I haven’t allowed myself a good night’s sleep; and I’ve not trained in my race outfit - a police costume bought off eBay for £15 - partly from fear of getting beaten up in my north London hood, and partly because I’ve not really trained much at all.

Oh, and I’m extremely hungover. Fortunately, I’m attempting Bordeaux’s Marathon du Médoc; a running event combining “wine, sports, fun and health”, which seems to actively encourage anything that’s normally discouraged in running. Held every September in France’s Médoc region, this sounds like the most idiotic race known to man. The course is 26.2 miles through scenic vineyards and the participants – in compulsory fancy dress - are expected to indulge in 23 glasses of the famed vintages en route, while also stuffing themselves with local specialities such as oysters, foie gras, cheese, steak and ice-cream. Brilliant.

My hangover, then, is in good company, and I’m not just referring to my running partner and fellow “police officer” Birdy, whose eyes are so bloodshot he looks like a zombie. Many of the 10,000 other participants have attended one of the event’s pasta parties the previous evening: a glorious mix of wine, carbohydrates and merriment designed, I suspect, to ensure that you forget you’re running a marathon the following morning. Or, in Birdy’s case, even on the day itself.

Yet the atmosphere at the packed start line is upbeat. Everyone is grinning, most are dancing, some are even whooping – a far cry from the sombre, nervous mood of my previous marathons.

The event has even more glitz and glamour this year - fireworks and dancers at the start line and an additional 1,500 runners to acknowledge the 30th anniversary of the first race. “The first official race didn’t take place until 1985, but it was meant to take place in 1984,” explains Vincent Fabre, the marathon’s president, when I question why the anniversary dates don’t quite add up. “There were some problems with administration – they’re very strict about health and safety over here.”

The Marathon du Médoc: Excessive alcohol consumption may result in some strange visions Photograph: Vicky Lane

Glancing at the pack of Smurfs already finishing off a bottle of vino (it’s 9.30am), and the oversized baby having a fag in the starting zone, I’m not entirely convinced regulations are quite as stringent as they would be back in the UK – though I’m hardly complaining.

I do have one concern though. Having – strangely enough – not really trained with the food and drink I intend to consume en route, I’m unsure what havoc they will wreak on my stomach. Luckily, a man whose costume consists of a toilet roll secured to his head reminds me. “Imodium,” I explain to Birdy, pulling the packet of pills out of my pocket and handing him some. “Some now and some for later, in case of... the worst.”

Having been advised by veterans that those who were serious about the Marathon du Médoc aimed to finish as close to the six-hour-30-minutes time limit as possible to take full advantage of the produce on offer, Birdy and I agree that our strategy is: take it slow. Too slow. The novelty of introducing wine to running is too much for our over-excited selves, and while slurping back our third glass of wine at Chateau Montrose – the first wine stop just over 5km along the track – it occurs to us that we’ve already taken almost an hour. Spotting the cut-off float dangerously close we decide to pick up the pace.

But after the first chateau, the stops come thick and fast, the wine and food – biscuits, waffles, fruit, sweets, cheese, bread, crackers – go down far too easily, and the temptation to stop for an impromptu boogie to the many wonderful local bands stationed along the route is too hard to resist.

Plus, it’s really hot: around 27 degrees without a cloud in sight. And the heat slows us down to walking pace along the stunning – but very exposed – country roads and vineyard tracks. As we approach Chateau Lafite Rothschild around halfway, we notice some runners have found an excellent way to cool down – by jumping into the Chateau’s lake. We decide to join them – along with our car keys we later realise. Who knew alcohol could affect good judgment?

It also affects the second half of a marathon, which, for the first time, I find easier than the first. Plodding along in my own merry way, I’m quite oblivious to the mileage we’re getting through. It’s Birdy who breaks into a spontaneous, projectile vomit around 18 miles (29km), necessitating another Imodium tablet. “Too late,” he shouts, seconds later, running off at a speed we could have done with a while back towards the nearest chemical toilet.

Finally, after mile 23, the oyster stop. God, the cool, lemony, saltiness washed down with white wine tastes incredible. To me, anyway. Half a mile from the end, Birdy keels over for his second vomit. Instantly a group of medics are around him checking that he’s OK. “He’s fine – just too much – you know,” I assure, making a drinking motion.

Indeed this marathon – to the organisers’ pride – has the most medical support of any in the world, not that it seems to need it. Unlike in the London and Paris marathons I only saw one floored person (a Smurf, surprise surprise) on the entire route. Maybe it’s because there is a less pressure to run fast - or maybe I was just too drunk to notice.

Finishers’ treats: not a granola bar in sight at the end of the Marathon du Médoc. Alka Seltzer might be handy, though Photograph: Vicky Lane

When we finally stumble over the finish line, sunburnt and tipsy, we’re happy. Until we realise that we have taken six hours and 52 minutes. What the hell happened? “You had fun!” says Fabre, when we meet up later. “Year after year, the Marathon du Médoc proves you can be healthy and safe while appreciating fine food, wine and our beautiful region. It isn’t about getting a good time – it’s about having a good time.”

He’s right. It’s been a long day, I’m still full of cold, and yet, undeniably, I’ve managed to have one of the most bizarre and brilliant experiences of my life. Even better, because of the heat, Birdy and I weren’t the only ones to be a bit on the slow side, so organisers extended the cut-off time by half an hour. It means that we are presented with a medal, and a splendid goody bag containing a souvenir bottle of wine and engraved red wine glasses. That beats the cereal bar they gave me in Paris.