Why regularly taking laxatives over the long term can be a bad idea

If you’ve ever been constipated you may have tried laxatives. They’re easy to get without a prescription and often help get things moving.

Certainly a lot of people use laxatives and some older people are very reliant on them to help with bowel function.

But you might have heard it’s not a good idea to take them over the long term. Even though serious complications from chronic laxative use are rare, they do happen. That’s why, whenever possible, long-term laxative use should be guided and monitored by a doctor.

Types of laxatives

There are five main types of laxatives (all are oral):

1. bulk-forming laxatives (also known as fibre laxatives), which absorb water to form a soft, bulky stool and prompt normal contraction of bowel muscles. Common brands include Metamucil and Benefiber

2. osmotic laxatives, which draw water into the colon to allow easier passage of stool. Common brands include Osmolax, Actilax and Movicol

3. stool softeners such as docusate (brand name Coloxyl), which acts like a detergent and allows fat and water to mix in with hard stool – this makes it softer and easier to pass

4. stimulant laxatives, which trigger rhythmic contractions of the bowel muscle. Common brands include Dulcolax, Bisalax and Senna

5. lubricant laxatives, which coat the bowel and soften the stool. A common brand is Parachoc.

Starting a laxative

Before starting a laxative you should try dietary and lifestyle changes such as:

• eating more foods with fibre in them, such as kiwifruit, corn, oats and brown rice
• drinking more water
• doing more exercise.

But if constipation persists, you might think about a laxative. Consider starting with gentler options, such as the bulk-forming laxatives or stool softeners, and implement those dietary and lifestyle changes listed above.

It’s a good idea to see your local doctor when starting a laxative; constipation may be a sign of something more concerning, especially if there are other symptoms such as rectal bleeding.

Your doctor can also advise whether laxatives might interact with any other medications you take.

Do laxatives cause a ‘lazy colon’?

Probably not. So where does this idea come from?

A case report published in the 1960s described bowel changes in a patient who had been taking stimulant laxatives for more than 40 years.

When the colon was examined, doctors noticed a reduced number of key cells in the colon. This sparked concern about whether long-term use of stimulant laxatives could result in damage to the gut, culminating in a “lazy colon” (also known as a cathartic colon). This is when the colon becomes an inert tube with no real muscle function to push along stool.

However, a later review of more than 70 publications describing 240 cases of stimulant laxative abuse found no cases of cathartic colon reported. Researchers concluded the prior cathartic colon cases might have been linked to a laxative called podophyllin that is now no longer recommended.

A review of 43 publications on the safety of stimulant laxatives discovered many of the studies were of poor quality, with small sample size. Confounding factors, such as medications and age, were often not being taken into account.

It found no good evidence chronic use of stimulant laxatives damages the gut.

That said, there are other good reasons not to take laxatives regularly and over the long term unless advised by a doctor who is monitoring your progress.

Gut symptoms and electrolytes

Laxative abuse is when someone takes laxatives to lose weight through frequent and repeated use of laxatives.

The most common symptom of laxative abuse is diarrhoea, which can mean abdominal cramps, nausea, vomiting and weight loss.

But laxative abuse can also disrupt the body’s electrolytes.

The main electrolyte in poo is potassium. As the body loses more and more potassium through diarrhoea, you can end up with lower blood potassium levels.

This can lead to:

• generalised muscle weakness
• heart complications
• changes in heart rhythm
• in extreme cases, stopping your heart beat, which can lead to death.

A 2020 systematic review of case reports found that laxative abuse can cause mild to severe cases of cardiac complications.

Laxative abuse can also lower other electrolytes, such as calcium and magnesium, leading to painful muscle contractions. Occasionally the kidney can be severely affected by chronic laxative abuse.

If you take just the recommended dose of laxatives, though, the risk of serious electrolyte complications is extremely low.

Depression, dementia and mental health

Two UK studies that examined a data set of approximately half a million participants found regular laxative use was associated with a higher risk of developing depression and dementia.

One theory is chronic laxative abuse could alter what’s known as the microbiome-gut-brain-axis (the way microbiota and the brain communicate) and lead to a higher risk of conditions such as depression and dementia.

Laxative abuse is commonly associated with eating disorders, so it’s important anyone found to be abusing laxatives also undergo a comprehensive mental health assessment. A plan might be needed to address the broader problem.

Safe when taken properly

Laxatives are obtained easily without a prescription and are very widely used in the community. They are certainly helpful for treating chronic constipation.

However, they can cause side effects such as diarrhoea and electrolyte imbalances. Long-term use and overuse can lead to problems.

It’s always a good idea to consult your doctor before starting laxatives, especially if you have other medical issues or are taking other medications.