Although laxatives are popular for constipation, particularly with older people who are often reliant on them for help with bowel function, doctors warn that serious complications, while rare, can and do happen, and that they may even cause depression, writes Vincent Ho in The Conversation.
There are five main types of laxatives (all oral):
- bulk-forming laxatives (fibre laxatives), which absorb water to form a soft, bulky stool and prompt normal contraction of bowel muscles;
- osmotic laxatives, which draw water into the colon to allow easier passage of stool;
- stool softeners such as docusate, which acts like a detergent and allows fat and water to mix in with hard stool – this makes it softer and easier to pass;
- stimulant laxatives, which trigger rhythmic contractions of the bowel muscle; and
- lubricant laxatives, which coat the bowel and soften the stool.
Starting a laxative
Before starting a laxative, patients should try dietary and lifestyle changes like eating more foods with fibre in them, such as kiwifruit, corn, oats and brown rice; drinking more water, and doing more exercise.
But if constipation persists, starting with gentle laxative options can be suggested, such as the bulk-forming laxatives or stool softeners, while implementing the dietary and lifestyle changes listed above.
Doctors should check whether the constipation may be a sign of something more concerning, especially if there are other symptoms such as rectal bleeding, and advise whether laxatives might interact with any other medications being taken.
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. The 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 the patient’s progress.
Gut symptoms and electrolytes
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, leading to:
- generalised muscle weakness;
- heart complications'
- changes in heart rhythm; and
- in extreme cases, stopping the 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 kidneys can be severely affected by chronic laxative abuse.
Taking just the recommended dose of laxatives, though, poses an extremely low risk of serious electrolyte complications.
Depression, dementia and mental health
Two UK studies that examined a dataset of half a million participants found regular laxative use was associated with a higher risk of developing depression and dementia.
One theory is that chronic laxative abuse could alter 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 undergoes a comprehensive mental health assessment. A plan might be needed to address the broader problem.
Vincent Ho, Associate Professor and Clinical Academic Gastroenterologist, Western Sydney University
See more from MedicalBrief archives:
Diet change better at relieving IBS than medicine – Swedish trial
Diet pills and laxatives abused by teens globally, meta-analysis finds
High-fat diet with antibiotic use linked to gut inflammation