For people living with irritable bowel syndrome (IBS), day-to-day life can revolve around finding a toilet quickly — or planning carefully to avoid needing one — but a lesser-known symptom can show up far from the bathroom.
Many IBS sufferers know the routine of leaving the house with an “emergency kit”, whether that’s herbal tea, dairy alternatives, or medications intended to handle flare-ups associated with the chronic condition.
Classic IBS issues such as stomach cramps, bloating, diarrhoea and constipation are widely recognised. However, a nutritionist has highlighted another unpleasant effect that patients regularly report.
Around one in five people are thought to experience IBS, and some of the most uncomfortable signs aren’t limited to the digestive tract. Nutritionist VJ Hamilton says that in certain cases there can even be a noticeable change in someone’s breath.
The reasoning is that disruption in the gut can influence the mouth, leading to strong bad breath — known as halitosis — when there’s an underlying imbalance affecting digestion.
Hamilton told Metro that ‘bad breath typically isn’t top of the list’ when it comes to diagnosing IBS, but she said many of her patients had noticed an unpleasant odour coming from their mouth.
Patients commonly describe a ‘sulphuric, musty, or slightly sour’ smell alongside their other symptoms. Hamilton added: “Sometimes it has that fermented quality to it, which tends to reflect what’s happening in the gut, particularly if there’s excess bacterial activity.”
Health guidance suggests IBS isn’t a direct cause of halitosis, but it can create gut conditions that make it more likely. As Hamilton put it: “If food isn’t being properly broken down, it can sit and ferment.”
She explained that a disrupted microbiome may contribute further: “If there’s an imbalance in gut bacteria, certain microbes can produce gases and compounds that affect breath.
“And when gut motility is slower, there’s more opportunity for that stagnation to build”.
Hamilton noted that this “smelly” symptom can often appear alongside bloating, another hallmark complaint in IBS. In her view, if the underlying imbalance remains, the breath issue may persist too.
While ordinary oral hygiene may help on the surface, Hamilton said repeated halitosis may require more than toothpaste or mouthwash, with the biggest improvements coming from steps that support overall gut function.
“This will usually mean improving digestion so food is properly broken down, addressing any microbial imbalance and supporting gut motility so the system is moving well,” she said.
She suggested that simple habits — like taking time to chew properly and allowing the body to rest after meals — may ease bloating over time. For more immediate support, she added there are also options some people explore to help reduce the odour.
Hamilton said this includes things like ‘digestive bitters or enzymes, or even looking at stomach acid levels if someone has ongoing bloating or heaviness.’ She also said that cutting back on constant snacking can give the digestive system time to fully process food between meals.
She added: “When digestion improves, you often see a reduction in that fermentative load that can contribute to changes in breath.”