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What causes extremely smelly farts?

Few human activities create as much hilarity as farting. But unfortunately, the culprit doesn't always find the situation quite as amusing. And when farting is excessive or unusually smelly it can cause misery for the person involved.

I promise I will try to get through this without resorting to double entendres, although given the subject matter it will be difficult. Many of us will have been the butt (you see?) of schoolboy humour. More polite options don't quite fit the bill, though. 'Passing wind' sounds like something a country and western star would sing about, and 'letting one go' sounds more like a job release than a gas release. So let's call a fart a fart and be done with it.

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Getting to the guts of the problem

Jennyjames posted a forum message to say that for the last two months she had been getting really bloated and passing the most foul-smelling gas ever.

She ate healthily, exercised regularly and was not overweight. Doctors had tested a stool sample but found it clear. She was told she had IBS and was prescribed Colofac® (mebeverine) tablets but these didn't help.

She had to air her bungalow every evening. She could not have visitors, had given up her job and was getting seriously depressed.

Jennyjames is clearly not alone. Her posting attracted 247 replies.

21st century doctors are supposed to go on about changes in lifestyle as well as pushing pills and whilst this condition is no different, it's always worth ruling out treatable underlying causes. Be87654 suggested getting tested for coeliac disease. Other causes can include diverticulitis (when small pouches in the wall of the large bowel, called 'diverticula', become infected) and scleroderma, a condition which causes thickening of the skin and sometimes the internal organs.

Tracy62295 wanted to make the forum aware that ovarian cancer can lead to bowel symptoms and that bloating in women over 40 shouldn't be ignored. Pookie64 noticed her smelly farts were caused by gabapentin, an anti-epileptic medicine. Other medicines that can do this are metformin, used for diabetes, and lactulose, a laxative.

What goes in must come out, and we mustn't forget simple mechanics. Swallowing too much air (aerophagy) often results in burping, but if the air gets trapped lower down the gut, it can only travel downwards. Stress, chewing gum, and smoking can all be associated with excessive air swallowing.

Food for thought

Forum posters identified many dietary factors which made the problem worse. JennyJames found that spaghetti Bolognaise, shepherd's pie and curry were the main offenders. Laurab68 mentioned lactose intolerance, in which the body has difficulty digesting lactose, leading to bowel symptoms. Kubie's problem was made worse by tuna and salmon, and Barrymanilow (I presume not the Barry Manilow) found it best to avoid dairy products.

Studies have found that the main culprits seem to be broccoli, Brussels sprouts, starchy foods such as potatoes, corn and noodles, and foods high in soluble fibre (eg, fruit, peas and beans). Other foods or beverages that have been implicated include fizzy drinks and whole grains. appropiate68639 identified fructose as being a trigger. This is found in fruit, artificial sweeteners and corn syrup used to sweeten many foods.

The best approach is to keep a diary and see if you can match your symptoms to any particular foods or drinks and try avoiding them for a while.

Peppe found that taking probiotics was helpful and this does have some support in the scientific world.

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The answer is blowin' in the wind

There's no one solution to this problem but forum posters have come up with several suggestions, several of which are supported by medical evidence. Charcoal tablets seem to be a popular choice. They can be bought over the counter and are meant to absorb gas in the bowel. They are not the answer for everyone, however; janus13 found they only helped if plenty of water was drunk and they didn't work for JeNean_L at all. Nora21180 got some benefit from a pair of underpants with a charcoal pad to absorb the smell. Carbon underwear is said to be more effective.

Paints recommended Pepto Bismol®. This is OK when taken occasionally for social occasions, but side effects such as constipation and dizziness limit its use.

Kasia96064 found peppermint useful. This has an effect on the movement of muscles in the gut. Other medicines with this effect are available on prescription.

Mebeverine and alverine combat gut spasms and are available over the counter. Simeticone may also be worth a try. It is also available over the counter and is said to break up bubbles in the stomach but the scientific evidence supporting it is weak.

Forum posters have come up with other suggestions which they have found helpful from their own experience. Amminiraw recommends chewing cumin seeds, mrskiranaya advocates chiropractic (it's all to do with hip alignment, apparently) and Peter98658 swears by turmeric. None of these is supported by vast amounts of scientific evidence but I've always been fairly laid back about unconventional treatments, providing they don't do any harm.

There. I managed to get through this feature without any unintentional double entendres. Hopefully, you'll find it helpful in getting to the bottom of your problem.

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The information on this page is peer reviewed by qualified clinicians.

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