Managing Gas and Odour With an Ostomy

Gas and odour are among the most common concerns reported by people living with an ostomy — and one of the most anxiety-provoking, particularly in social situations. The reassuring reality is that both are largely manageable through a combination of dietary awareness, correct pouching technique, and a few targeted practical strategies. This article explains why gas and odour occur, what influences them, and how to minimise their impact on daily life.

Why Gas and Odour Occur With an Ostomy

The digestive tract naturally produces gas as a by-product of bacterial fermentation of food residue in the large bowel. This process continues after stoma formation; the difference is simply that gas now exits via the stoma rather than being partially reabsorbed or passed conventionally.

Odour arises from volatile sulphur compounds, ammonia, and other metabolic by-products within stool or urine. The intensity of odour depends on the individual’s gut flora, diet, transit time, and the type of stoma:

• Colostomy output is formed or semi-formed and tends to carry more odour than ileostomy output.
• Ileostomy output is liquid to porridge-like and passes more rapidly through the gut, which generally means less fermentation — though volume of gas can still be significant.
• Urostomy odour is primarily influenced by hydration status and urinary tract health rather than fermentation.

The Role of Diet

Foods That Increase Gas

Certain foods are well-established gas producers due to their content of fermentable carbohydrates (FODMAPs) and soluble fibre:

• Pulses and legumes: beans, lentils, chickpeas, peas
• Cruciferous vegetables: cabbage, broccoli, cauliflower, Brussels sprouts
• Alliums: onions, garlic, leeks
• Carbonated drinks: fizzy water, soft drinks, beer
• Swallowed air: from eating quickly, chewing gum, or drinking through a straw

Because individual responses vary considerably, a food diary is the most practical diagnostic tool. Introduce or reintroduce foods one at a time so that triggers can be clearly identified.

Foods That Increase Odour

Foods with a high sulphur content or pungent aromatic compounds are the most common dietary contributors to stoma odour:

• Eggs, fish, and red meat (particularly in higher quantities)
• Asparagus (also a well-known cause of strong urine odour)
• Garlic and onions
• Strong-flavoured cheeses
• Alcohol

Foods That May Help

Some dietary choices are associated with reduced gas or odour, though evidence is largely observational:

• Natural yoghurt with live cultures may help regulate gut flora.
• Parsley, mint, and lemon juice are traditionally cited as natural deodorising aids.
• Adequate fluid intake — particularly important for urostomy patients to dilute urinary odour.
• Buttermilk and cranberry juice are sometimes recommended for urostomy odour, though clinical evidence remains limited.

Pouching System Considerations

The single most effective barrier against odour is a correctly fitting, intact pouching system. A well-sealed pouch should contain odour completely between emptying and changing.

Charcoal Filters

Many pouches are available with integrated charcoal vent filters, which allow gas to escape gradually while trapping odour-causing molecules. Filters work most reliably with formed output; they can become blocked when output is very liquid, or saturated by contact with water. Covering the filter during showering or swimming prolongs its effectiveness.

Pouch Deodorant Products

Liquid or gel deodorant drops designed for use inside the pouch can significantly reduce odour at emptying. These are instilled into the pouch at each change or emptying. Enzymatic or charcoal-based formulations are available; your stoma care nurse can advise on generic options suitable for your pouch type.

Pouch Integrity

Odour leaking between changes almost always indicates a seal problem rather than a product limitation. Common causes include:

• Incorrect stoma aperture size (allowing faecal contact with the skin or flange edge)
• Lifting or peeling of the adhesive baseplate
• Delayed pouch change (output degrading the adhesive)
• Creases, folds, or scar tissue preventing a flush seal

If persistent leakage occurs, a review with a stoma care nurse is strongly advisable.

Lifestyle and Behavioural Strategies

Eating Habits

• Eat slowly and chew thoroughly to reduce the amount of air swallowed.
• Avoid talking while eating, which increases air ingestion.
• Eat regularly rather than skipping meals, which can lead to erratic output.
• Limit chewing gum and carbonated beverages, especially before social events.

Timing and Social Planning

Many people find that their stoma is most active in the two to three hours after eating. Planning meals and social activities with this in mind — for example, eating earlier before an event — can help reduce the likelihood of high output or gas at inconvenient times.

Room Deodorisers and Bathroom Products

Using a purpose-made ostomy pouch deodorant or a general bathroom air spray when emptying the pouch in a public or shared toilet can discreetly manage odour. Some people use a small amount of toilet tissue or kitchen roll in the toilet bowl before emptying to reduce splashing and ambient odour.

When Odour Signals a Medical Concern

A sudden change in stoma odour — particularly if accompanied by changes in output consistency, colour, abdominal pain, or fever — can occasionally indicate an underlying issue such as:

• Intestinal infection (including Clostridioides difficile or enteric pathogens)
• Urinary tract infection (for urostomy patients — often the first noticeable symptom)
• Stoma complications such as mucosal prolapse or necrosis

Any unexplained or persistent change in odour warrants prompt assessment by a clinician.

The Bottom Line

Gas and odour after ostomy surgery are normal, common, and — with the right strategies — very manageable. A well-fitting pouching system forms the foundation of odour control, while dietary adjustments and behavioural habits help reduce gas production at source. Every person’s digestive system is different, so an approach tailored to individual triggers and lifestyle is always more effective than a generic prescription. Consult your stoma care nurse or specialist clinician for personalised advice; they can assess your pouching technique, recommend appropriate accessories, and rule out any clinical causes of odour change.