Functional Constipation in Adults: Causes, Symptoms & UK Management

Functional constipation refers to chronic difficulties with bowel movements that are not caused by a specific underlying disease or structural abnormality. In the UK, it is one of the most common reasons for primary care consultations. According to NICE (National Institute for Health and Care Excellence), it is characterised by infrequent defecation, difficult stool passage, or both.

Unlike acute constipation, which might follow a short illness or a change in diet, functional constipation is persistent. It often involves a slower transit time through the colon or a coordination issue with the pelvic floor muscles. For many British adults, this condition can significantly impact quality of life, leading to bloating, discomfort, and psychological distress.

The symptoms of functional constipation are varied but generally follow the Rome IV criteria, which are used by doctors across the UK to standardise diagnosis. You may be experiencing functional constipation if you have had at least two of the following for the last three months:

• Straining during at least 25% of bowel movements.
• Lumpy or hard stools (often described as Bristol Stool Chart type 1 or 2).
• A sensation of incomplete evacuation.
• A sensation of anorectal obstruction or blockage.
• Fewer than three spontaneous bowel movements per week.

It is important to note that these symptoms must occur in the absence of irritable bowel syndrome (IBS) or other inflammatory conditions to be classified strictly as functional constipation.

While by definition there is no single 'disease' causing functional constipation, several lifestyle factors common in the UK contribute to its development:

• Low Dietary Fibre: A diet lacking in wholegrains, fruits, and vegetables can slow down intestinal transit.
• Dehydration: Inadequate fluid intake makes stools harder and more difficult to pass.
• Sedentary Lifestyle: Lack of physical activity can reduce the efficiency of the digestive system.
• Ignoring the Urge: Repeatedly delaying a bowel movement (often due to a busy work schedule) can lead to the rectum becoming less sensitive.
• Medication: Certain painkillers, antidepressants, and iron supplements can cause constipation as a side effect.

Following NHS guidance, the first line of treatment for functional constipation is lifestyle modification. Small, consistent changes can often resolve symptoms without the need for long-term medication.

Increase Fibre Gradually

Aim for around 30g of fibre a day. However, it is vital to increase your intake gradually to avoid excess wind and bloating. Focus on oats, beans, pulses, and brown rice.

Optimise Hydration

Ensure you are drinking 6 to 8 glasses of water daily. Fibre needs water to work effectively; increasing fibre without increasing water can sometimes make constipation worse.

Establish a Routine

Try to set aside a regular time each day for a bowel movement, ideally after breakfast when the colon is most active. Use a small footstool to elevate your knees above your hips while sitting on the toilet, as this creates a better anatomical angle for passing stool.

If lifestyle changes have not improved your symptoms after several weeks, it is time to seek professional advice. You can speak to a GP online in the UK to discuss your symptoms from the comfort of your home.

An online GP consultation is particularly useful for:

• Reviewing your current medications to see if any are causing constipation.
• Discussing the appropriate use of laxatives, such as bulk-forming, osmotic, or stimulant varieties.
• Determining if further tests (like blood tests for thyroid function) are necessary.
• Receiving a prescription for stronger treatments if over-the-counter options have failed.

Our clinicians provide evidence-based advice aligned with UK clinical standards, ensuring you receive the same level of care as an in-person visit.

If lifestyle measures are insufficient, your GP may recommend a stepped approach to pharmacological treatment:

• Bulk-forming Laxatives: Such as ispaghula husk, which work by increasing the 'bulk' of the stool and retaining water.
• Osmotic Laxatives: Such as macrogols or lactulose, which draw water into the colon to soften the stool.
• Stimulant Laxatives: Such as senna or bisacodyl, used if stools are soft but still difficult to pass. These should generally be used on a short-term basis.

In cases where these do not work, a GP may investigate pelvic floor dysfunction or refer you to a specialist for further diagnostic imaging or biofeedback therapy.