Why sober drivers are testing drunk

Sober drivers testing positive in Spain? The gut condition confusing breathalysers and baffling police. You don’t need a night of booze to fail a breathalyser test.

Guardia Civil officers across Spain are scratching their heads after cases of seemingly sober drivers testing positive for alcohol — without touching a single caña. And it’s not a faulty breathalyser or a dodgy excuse. Welcome to the weird and worrying world of Auto-Brewery Syndrome, where your gut ferments carbs into alcohol… and you take the rap.

You’re stone-cold sober, haven’t touched a drop, and yet — bam! — you’re flagged down at a routine checkpoint, blow into the breathalyser… and it lights up like it’s New Year’s Eve.

Think you’ve been stitched up? Think again.

Your own gut could be turning into a one-man or one-woman microbrewery, pumping alcohol into your bloodstream after a plate of pasta.

What is Auto-Brewery Syndrome? The rare gut condition that turns carbs into alcohol

Known scientifically as Auto-brewery Syndrome (ABS), or more politely, gut fermentation syndrome, this rare condition causes your intestines to ferment carbohydrates into ethanol. In plain English? Your gut’s getting tipsy on your behalf.

It’s so rare, most doctors have never seen it and most police officers have never heard of it.

What causes ABS? The gut bacteria behind your body’s hidden alcohol problem

The culprit? A riot in the gut’s microbiome. A misbehaving mix of yeasts and bacteria that turn sugars and starches into pure alcohol.

Causes can include:

• Digestive disorders – Conditions like IBS, SIBO, or coeliac disease mess with your carb digestion.
• Antibiotics – Long-term use can wipe out good bacteria and let the yeast run wild.
• Liver disease – If your liver’s not clearing alcohol properly, your gut brew sticks around.

Auto-Brewery Syndrome symptoms: when your body acts drunk without a single drink

People suffering from Auto-brewery Syndrome might act drunk without a single drop passing their lips. Common symptoms include:

• Slurred speech, poor coordination
• Dizziness and mental fog
• Bloating, nausea and vomiting
• Low blood sugar crashes
• Confusion and fatigue

In extreme cases, it’s enough to register a blood-alcohol level that would legally get you banned from driving in Spain — or even locked up.

While it sounds like a dodgy excuse dreamt up at 3AM in a kebab queue, Auto-brewery Syndrome has been medically documented around the world.

Doctors have seen some shocking cases of this rare condition. In one reported by the BMJ in 2019, a man had a blood alcohol level of 0.4% — five times over the UK drink-drive limit — without drinking any alcohol at all.

Other cases in the US, Japan, and Europe have shown people reaching levels between 0.08% and 0.3%, just from their own guts brewing booze after eating carbs.

Belgian man cleared of drink driving in April after doctors prove his gut was brewing alcohol on its own

One of the most jaw-dropping cases to date hit headlines in April 2024, when a 40-year-old Belgian brewery worker was cleared of drink driving after doctors confirmed his gut was the real culprit.

Despite being pulled over probably smelling like a brewery twice in 2022 and blowing over the legal limit both times, the man insisted he’d only had “two beers the day before.”

It turns out, he was telling the truth.

A panel of three doctors diagnosed him with Auto-Brewery Syndrome, and one test showed his body massively converted sugar into alcohol — all without touching a drop.

In what his lawyer called an “act of God” (or in legal terms, force majeure), the Bruges judge ruled in his favour but warned: either change your diet or install an alcolock, or next time you might not be so lucky.

Here in Spain, experts are warning that this syndrome — though rare — should be taken seriously. And the law may need to catch up.

Could you have Auto-Brewery Syndrome? Signs it’s time to see a doctor, not a bartender

Don’t panic — but don’t ignore it.

The chances of having ABS are tiny. But if you:

• Often feel tipsy without drinking
• Have gut issues, fatigue or unexplained symptoms
• Or blow positive when you’re tea-total…

…then it might be worth speaking to a doctor, not a bartender.

Drunk on bread? It might be your gut.

You don’t need to down six lagers to get breathalysed these days — your gut might be the real party animal.

So next time someone claims they were “drunk on bread” — they might not be half-baked after all. Just fermented.

Stay tuned to the Euro Weekly News for more Spanish living.

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