Why does increasing fibre cause more gas?

Fibre is fermented by bacteria in the large intestine, and this fermentation produces gas. When you increase fibre intake — which is commonly recommended for conditions like hemorrhoids and fissures — gas production often increases, particularly in the first few weeks. Increasing fibre gradually and drinking adequate water helps minimise this. For most people, the gas settles as the gut microbiome adjusts.

Can gas make hemorrhoid or fissure pain worse?

Passing gas can be uncomfortable when there is active inflammation, swelling, or a fissure. The distension of the anal canal as gas passes can trigger pain or spasm. Some people describe gas pain as a significant secondary symptom alongside their primary condition. Managing gas production through dietary adjustments can help reduce this.

Are there foods that reduce gas?

Foods that tend to produce less gas include rice, bananas, potatoes, lean proteins, and many cooked vegetables. Peppermint tea is commonly described as helpful for bloating. Avoiding or reducing high-gas foods like beans, cruciferous vegetables, onions, and carbonated drinks can help during symptomatic periods — though these are healthy foods that can be reintroduced gradually.

Should I try a low FODMAP diet?

A low FODMAP diet — which reduces certain fermentable carbohydrates — is commonly recommended for IBS-related bloating and gas. It is an elimination diet meant to be followed temporarily to identify triggers, not permanently. Working with a dietitian is recommended, as the diet is complex and unnecessarily restricting foods long-term can affect nutrition.

Gas and bloating with colorectal issues

At a glance

Gas and bloating are among the most common complaints people have when managing colorectal conditions. The irony is that many of the dietary changes recommended for conditions like hemorrhoids and fissures — particularly increasing fibre — can initially make gas worse.

This guide covers why gas and bloating are so common alongside colorectal conditions, what makes them worse, and practical approaches for managing both.

Why it happens

The fibre connection

Increased fibre intake is one of the most commonly recommended changes for colorectal conditions. Fibre helps by creating softer, bulkier stools that pass with less straining. But fibre is also fermented by gut bacteria, producing gas.

When you increase fibre intake, your gut microbiome needs time to adjust. During this adjustment period — typically two to four weeks — gas production often increases. This is a temporary phase, but it can be uncomfortable, especially when combined with a condition that makes passing gas painful.

IBS overlap

Many people with colorectal conditions also have IBS or IBS-like symptoms. The altered gut motility and sensitivity that characterise IBS frequently include excessive gas production and bloating as prominent features.

Medication effects

Medications commonly used alongside colorectal conditions can contribute to gas:

Stool softeners — some types increase gas production
Fibre supplements — particularly when first started
Laxatives — can alter gut flora and increase gas
Antibiotics — post-procedure antibiotics can disrupt gut bacteria balance

Stress and anxiety

The gut-brain connection is well established. Stress and anxiety — which are common when dealing with chronic colorectal conditions — can alter gut motility and increase gas production and bloating perception.

Managing gas alongside a colorectal condition

Fibre adjustment

Increase gradually — add fibre slowly over two to three weeks rather than all at once
Choose low-gas fibre sources — oats, psyllium husk, and cooked vegetables tend to produce less gas than beans, cruciferous vegetables, and bran
Pair with water — fibre without adequate water can worsen both gas and constipation
Be patient — gas typically reduces within two to four weeks as the gut adjusts

Dietary strategies

Identify trigger foods — keep a simple food diary to spot patterns
Eat slowly — rushing meals increases the amount of air swallowed
Smaller, more frequent meals — easier on the digestive system than large meals
Reduce carbonated drinks — they add gas directly
Limit artificial sweeteners — sorbitol and similar sugar alcohols increase gas production
Consider peppermint — peppermint tea or capsules are commonly described as helpful for gas and bloating

When passing gas is painful

For people with conditions that make passing gas uncomfortable:

Warm compresses on the abdomen can encourage gentle gas movement
Gentle walking helps gas move through the digestive system
Position changes — lying on the left side can help gas travel through the colon
Avoiding gas-producing foods during flare-ups, reintroducing them gradually as symptoms settle
Simethicone — an over-the-counter product that may help break up gas bubbles

The low FODMAP approach

For people with significant IBS-related gas and bloating, a low FODMAP diet may be helpful. FODMAPs are specific types of fermentable carbohydrates found in many common foods. The diet involves:

Elimination phase — removing high FODMAP foods for two to six weeks
Reintroduction phase — systematically reintroducing each FODMAP group to identify specific triggers
Maintenance phase — a personalised diet that avoids only the specific triggers identified

This is best done with guidance from a dietitian, as the diet is complex and unnecessarily restrictive long-term.

The social dimension

Gas and bloating have a social impact that is often underestimated, particularly when combined with an already stigmatised colorectal condition. People describe anxiety about gas in work meetings, social situations, and intimate moments. Acknowledging this social dimension is important — it is a real quality-of-life concern, not a trivial inconvenience.